Method and apparatus for adaptive antenna scaling in a communication system

Abstract

A method of a terminal comprises the steps of: receiving first configuration information on a first CSI-RS resource from a base station; receiving second configuration information for a CSI reporting operation from the base station; based on the first configuration information and the second configuration information, receiving the CSI-RS through M CSI-RS antenna ports (wherein M is a natural number less than or equal to L), the M CSI-RS antenna ports being a first subset of L CSI-RS antenna ports forming the first CSI-RS; determining a first PMI based on the M CSI-RS antenna ports; and transmitting a CSI report including the first PMI to the base station, in which the step of determining the first PMI is performed at least on the basis of a codebook in which sizes of the first dimension and the second dimension are N1 and N2, respectively, and N1 and N2 may each be determined as a divisor of M.

Description

Technical Field

[0001] The present disclosure relates to a method and apparatus for adaptive antenna scaling, and more specifically, to a method and apparatus for adaptively scaling antennas in a wireless communication system to enhance network power efficiency, and a corresponding method and apparatus for transmitting a channel state information reference signal (CSI-RS). Background Art

[0002] As the core infrastructure driving the development of the ICT industry, mobile communication systems are evolving to overcome the shortcomings and limitations of traditional communication solutions. Mobile communication systems can provide advanced services in various use cases, such as enhanced Mobile Broadband (eMBB), ultra-reliable low-latency communication (URLLC), massive machine-type communication (mMTC), ultra-low power, ultra-precision, and ultra-wide coverage. Furthermore, to achieve various performance metrics, mobile communication systems are trending towards discovering new communication bands in mid-band and high-band spectrum and more actively utilizing multi-antenna technology.

[0003] Accordingly, while the communication performance and processing capabilities of communication nodes can be enhanced, the power consumption of the communication nodes that make up the mobile communication system may increase accordingly. In particular, in order to support global carbon neutrality efforts and reduce the operating costs of communication service providers, there is a growing demand for technologies that reduce not only the power consumption of terminals but also the power consumption of networks (especially base stations). Summary of the Invention

[0004] Technical issues

[0005] The present disclosure aims to provide a method and apparatus for adaptively scaling antennas to enhance network power efficiency in a wireless communication system, and a corresponding method and apparatus for transmitting a channel state information reference signal (CSI-RS).

[0006] Technical Solution

[0007] According to an exemplary embodiment of the present disclosure for achieving the above-mentioned objectives, a method of a terminal may include: receiving first configuration information about a first channel state information-reference signal (CSI-RS) resource from a base station; receiving second configuration information for a CSI reporting operation from the base station; receiving CSI-RS through M CSI-RS antenna ports based on the first configuration information and the second configuration information, wherein the M CSI-RS antenna ports are a first subset of L CSI-RS antenna ports corresponding to the first CSI-RS resource, wherein L is a natural number and M is a natural number equal to or less than L; determining a first precoding matrix indicator (PMI) based on the M CSI-RS antenna ports; and sending a CSI report including the first PMI to the base station, wherein the determination of the first PMI can be performed based on a codebook, wherein in the codebook, the sizes of at least the first dimension and the second dimension are N1 and N2, respectively, and N1 and N2 can each be determined as a divisor of M.

[0008] The second configuration information may include configuration information of multiple CSI reporting subconfigurations, the first CSI-RS resource may be referenced by a first CSI reporting subconfiguration included in the multiple CSI reporting subconfigurations, and the first PMI may be CSI corresponding to the first CSI reporting subconfiguration.

[0009] The second CSI-RS resource can be additionally referenced by the first CSI reporting subconfiguration, and the CSI corresponding to the first CSI reporting subconfiguration can include a CSI-RS resource indicator (CRI), and the CRI can be an index of the first CSI-RS resource or the second CSI-RS resource.

[0010] The second CSI-RS resource may correspond to L CSI-RS antenna ports and may belong to the same CSI-RS resource set as the first CSI-RS.

[0011] The M CSI-RS antenna ports may be represented as a bitmap having a length of L, and the bitmap may be transmitted from the base station to the terminal while being included in the second configuration information.

[0012] The antenna port numbers of the M CSI-RS antenna ports may be reallocated in ascending order of consecutive values ​​from P to (P+M-1), where P may be 0 or a natural number, and the first PMI may be determined based on the reallocated antenna port numbers.

[0013] M=2*N1*N2, N1 may be a value based on the number of CSI-RS antenna ports corresponding to the first dimension, and N2 may be a value based on the number of CSI-RS antenna ports corresponding to the second dimension.

[0014] M=2*N1*N2*Ng, where N1 may be a value based on the number of CSI-RS antenna ports corresponding to the first dimension, N2 may be a value based on the number of CSI-RS antenna ports corresponding to the second dimension, Ng may be the number of antenna panels, and the codebook may be a codebook for multiple panels consisting of Ng panels.

[0015] The method may further include receiving a CSI-RS through M2 CSI-RS antenna ports, where the M2 CSI-RS antenna ports are a second subset of the L CSI-RS antenna ports; and determining a second PMI based on the M2 CSI-RS antenna ports.

[0016] The second PMI may be included in the CSI report and sent to the base station based on an indication of a higher layer message.

[0017] The first CSI-RS resource may be referenced by a second CSI reporting subconfiguration included in a plurality of CSI reporting subconfigurations, and the second PMI may be CSI corresponding to the second CSI reporting subconfiguration.

[0018] According to another exemplary embodiment of the present disclosure for achieving the above-mentioned objectives, a method of a base station may include: sending first configuration information about a first channel state information-reference signal (CSI-RS) resource to a terminal; sending second configuration information for CSI reporting to the terminal; sending CSI-RS to the terminal through all or part of L CSI-RS antenna ports corresponding to the first CSI-RS resource, where L is a natural number; and receiving a CSI report from the terminal including a first precoding matrix indicator (PMI) determined based on M CSI-RS antenna ports, where the M CSI-RS antenna ports are a first subset of the L CSI-RS antenna ports determined based on the first configuration information and the second configuration information, where the first PMI can be determined based on a codebook, where in the codebook, the sizes of at least the first dimension and the second dimension are N1 and N2, respectively, and N1 and N2 can each be determined as a divisor of M.

[0019] The second configuration information may include configuration information of multiple CSI reporting subconfigurations, the first CSI-RS resource may be referenced by a first CSI reporting subconfiguration included in the multiple CSI reporting subconfigurations, and the first PMI may be CSI corresponding to the first CSI reporting subconfiguration.

[0020] The second CSI-RS resource can be additionally referenced by the first CSI reporting subconfiguration, and the CSI corresponding to the first CSI reporting subconfiguration can include a CSI-RS resource indicator (CRI), and the CRI can be an index of the first CSI-RS resource or the second CSI-RS resource.

[0021] The second CSI-RS resource may correspond to L CSI-RS antenna ports and may belong to the same CSI-RS resource set as the first CSI-RS.

[0022] The M CSI-RS antenna ports may be represented as a bitmap having a length of L, and the bitmap may be transmitted from the base station to the terminal while being included in the second configuration information.

[0023] The antenna port numbers of the M CSI-RS antenna ports may be reallocated in ascending order of consecutive values ​​from P to (P+M-1), where P may be 0 or a natural number, and the first PMI may be determined based on the reallocated antenna port numbers.

[0024] M=2*N1*N2, N1 may be a value based on the number of CSI-RS antenna ports corresponding to the first dimension, and N2 may be a value based on the number of CSI-RS antenna ports corresponding to the second dimension.

[0025] M=2*N1*N2*Ng, where N1 may be a value based on the number of CSI-RS antenna ports corresponding to the first dimension, N2 may be a value based on the number of CSI-RS antenna ports corresponding to the second dimension, Ng may be the number of antenna panels, and the codebook may be a codebook for multiple panels consisting of Ng panels.

[0026] According to another exemplary embodiment of the present disclosure for achieving the above-mentioned objectives, a terminal may include a processor, and the processor may cause the terminal to perform the following operations: receive first configuration information about a first channel state information-reference signal (CSI-RS) resource from a base station; receive second configuration information for a CSI reporting operation from the base station; receive CSI-RS through M CSI-RS antenna ports based on the first configuration information and the second configuration information, wherein the M CSI-RS antenna ports are a first subset of L CSI-RS antenna ports corresponding to the first CSI-RS resource, wherein L is a natural number and M is a natural number equal to or less than L; determine a first precoding matrix indicator (PMI) based on the M CSI-RS antenna ports; and send a CSI report including the first PMI to the base station, wherein the determination of the first PMI may be performed based on a codebook, wherein in the codebook, sizes of at least the first dimension and the second dimension are N1 and N2, respectively, and N1 and N2 may each be determined as a divisor of M.

[0027] Beneficial effects

[0028] Using the method and apparatus according to the present disclosure as described above, antennas used for communication can be adaptively scaled to improve the power efficiency of the network. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0030] Figure 2 is a block diagram illustrating a first exemplary embodiment of a communication node constituting a communication system.

[0031] Figure 3 is a conceptual diagram illustrating a first exemplary embodiment of a resource mapping method for CSI-RS antenna ports.

[0032] Figure 4 is a conceptual diagram illustrating a first exemplary embodiment of a mapping method between CSI-RS antenna ports and TXRUs or physical antenna elements.

[0033] Figure 5a is a conceptual diagram illustrating a first exemplary embodiment of a TXRU quiescing method, and Figure 5b is a conceptual diagram illustrating a second exemplary embodiment of a TXRU silencing method.

[0034] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of a CSI reporting method based on multiple CSI-RS antenna port sets.

[0035] Figure 7 is a conceptual diagram illustrating a first exemplary embodiment of a method for configuring multiple CSI-RS antenna port sets.

[0036] Figure 8 is a conceptual diagram illustrating a second exemplary embodiment of a method for configuring multiple CSI-RS antenna port sets.

[0037] Figure 9 is a conceptual diagram illustrating a second exemplary embodiment of a CSI reporting method based on multiple CSI-RS antenna port sets.

[0038] Figure 10 is a conceptual diagram illustrating a first exemplary embodiment of a resource mapping method for a CSI-RS antenna port set.

[0039] Figure 11 is a conceptual diagram illustrating a second exemplary embodiment of a resource mapping method for a CSI-RS antenna port set.

[0040] Figure 12 is a conceptual diagram illustrating a third exemplary embodiment of a resource mapping method for a CSI-RS antenna port set. DETAILED DESCRIPTION

[0041] While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will be described in detail herein. However, it should be understood that there is no intention to limit the present disclosure to the particular forms disclosed, but on the contrary, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure. Throughout the description of the drawings, like reference numerals refer to like elements.

[0042] It should be understood that although the terms first, second, etc. can be used to describe various elements in this article, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of this disclosure, the first element can be referred to as the second element, and similarly, the second element can be referred to as the first element. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] In exemplary embodiments of the present disclosure, “at least one of A and B” may refer to “at least one of A or B” or “at least one of a combination of one or more of A and B.” Furthermore, “one or more of A and B” may refer to “one or more of A or B” or “one or more of a combination of one or more of A and B.”

[0044] It should be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Other words used to describe the relationship between elements should be interpreted in a similar manner (i.e., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

[0045] The terms used herein are used only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular is intended to include the plural, unless the context clearly indicates otherwise. It will be further understood that the terms "comprise," "include," "include," and / or "comprising" when used herein specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless explicitly defined as such herein.

[0047] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. In order to facilitate general understanding when describing the present disclosure, the same components in the drawings are represented by the same reference numerals, and their repeated description will be omitted.

[0048] A communication system to which an exemplary embodiment according to the present disclosure is applied will be described. The communication system may be a 4G communication system (e.g., a long term evolution (LTE) communication system or an LTE-A communication system), a 5G communication system (e.g., a new radio (NR) communication system), a sixth generation (6G) communication system, or the like. The 4G communication system may support communication in a frequency band of 6 GHz or lower, and the 5G communication system may support communication in a frequency band of 6 GHz or higher and a frequency band of 6 GHz or lower. The application of the communication system according to the exemplary embodiment of the present disclosure is not limited to the content described below, and the exemplary embodiment according to the present disclosure may be applied to various communication systems. Here, the communication system may be used in the same sense as the communication network, “LTE” may refer to a “4G communication system”, “LTE communication system” or “LTE-A communication system”, and “NR” may refer to a “5G communication system” or “NR communication system”.

[0049] In an exemplary embodiment, “configuration of an operation (e.g., a transmission operation)” may mean “signaling configuration information (e.g., information element, parameter) for the operation” and / or “signaling information indicating execution of the operation”. “Configuration of an information element (e.g., parameter)” may mean signaling the corresponding information element. “Configuration of resources (e.g., resource region)” may mean signaling configuration information of the corresponding resource. Signaling may be performed based on at least one of system information (SI) signaling (e.g., transmission of system information blocks (SIBs) and / or master information blocks (MIBs)), RRC signaling (e.g., transmission of RRC parameters and / or higher layer parameters), MAC control element (CE) signaling, PHY signaling (e.g., transmission of downlink control information (DCI), uplink control information (UCI), and / or bypass control information (SCI)), or a combination thereof.

[0050] Figure 1 is a conceptual diagram illustrating a first exemplary embodiment of a communication system.

[0051] refer to Figure 1 , the communication system 100 may include a plurality of communication nodes 110-1, 110-2, 110-3, 120-1, 120-2, 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. In addition, the communication system 100 may further include a core network (e.g., a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), and a mobility management entity (MME)). When the communication system 100 is a 5G communication system (e.g., a new radio (NR) system), the core network may include an access and mobility management function (AMF), a user plane function (UPF), a session management function (SMF), and the like.

[0052] The plurality of communication nodes 110 to 130 may support communication protocols defined in the 3rd Generation Partnership Project (3GPP) technical specifications (eg, LTE communication protocol, LTE-A communication protocol, NR communication protocol, etc.). The plurality of communication nodes 110 to 130 may support a communication protocol based on code division multiple access (CDMA), a communication protocol based on wideband CDMA (WCDMA), a communication protocol based on time division multiple access (TDMA), a communication protocol based on frequency division multiple access (FDMA), a communication protocol based on orthogonal frequency division multiplexing (OFDM), a communication protocol based on filtered OFDM, a communication protocol based on cyclic prefix OFDM (CP-OFDM), a communication protocol based on discrete Fourier transform spread OFDM (DFT-s-OFDM), a communication protocol based on orthogonal frequency division multiple access (OFDMA), a communication protocol based on single carrier FDMA (SC-FDMA), a communication protocol based on non-orthogonal multiple access (NOMA), a communication protocol based on generalized frequency division multiplexing (GFDM), a communication protocol based on filter band multi-carrier (FBMC), a communication protocol based on universal filter multi-carrier (UFMC), a communication protocol based on spatial division multiple access (SDMA), etc. Each of the plurality of communication nodes may represent a device or apparatus. The exemplary embodiments may be performed by an apparatus or device. The structure of the apparatus (or device) may be as follows.

[0053] Figure 2 is a block diagram illustrating a first exemplary embodiment of a communication node constituting a communication system.

[0054] refer to Figure 2 The communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to a network for performing communication. In addition, the communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, etc. The various components included in the communication node 200 can communicate with each other when connected through a bus 270.

[0055] The processor 210 may execute a program stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which the method according to an embodiment of the present disclosure is executed. Each of the memory 220 and the storage device 260 may be composed of at least one of a volatile storage medium and a non-volatile storage medium. For example, the memory 220 may include at least one of a read-only memory (ROM) and a random access memory (RAM).

[0056] Reference again Figure 1 , the communication system 100 may include a plurality of base stations 110-1, 110-2, 110-3, 120-1, and 120-2, and a plurality of terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6. Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 may form a macro cell, and each of the fourth base station 120-1 and the fifth base station 120-2 may form a small cell. The fourth base station 120-1, the third terminal 130-3, and the fourth terminal 130-4 may belong to the cell coverage of the first base station 110-1. Moreover, the second terminal 130-2, the fourth terminal 130-4, and the fifth terminal 130-5 may belong to the cell coverage of the second base station 110-2. In addition, the fifth base station 120-2, the fourth terminal 130-4, the fifth terminal 130-5, and the sixth terminal 130-6 may belong to the cell coverage of the third base station 110-3. Moreover, the first terminal 130-1 may belong to the cell coverage of the fourth base station 120-1, and the sixth terminal 130-6 may belong to the cell coverage of the fifth base station 120-2.

[0057] Here, each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can be referred to as a NodeB (NB), an evolved NodeB (eNB), a gNB, an advanced base station (ABS), a high reliability base station (HR-BS), a base transceiver station (BTS), a radio base station, a radio transceiver, an access point (AP), an access node, a radio access station (RAS), a mobile multi-hop relay base station (MMR-BS), a relay station (RS), an advanced relay station (ARS), a high reliability relay station (HR-RS), a home NodeB (HNB), a home eNodeB (HeNB), a road side unit (RSU), a radio remote head (RRH), a transmission point (TP), a transmission and reception point (TRP), etc.

[0058] Each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5 and 130-6 can be referred to as a user equipment (UE), terminal equipment (TE), advanced mobile station (AMS), high reliability mobile station (HR-MS), terminal, access terminal, mobile terminal, station, subscriber station, mobile station, portable subscriber station, node, device, on-board unit (OBU), etc.

[0059] In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can operate in the same frequency band or in different frequency bands. The multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can be connected to each other via an ideal backhaul link or a non-ideal backhaul link, and exchange information with each other via the ideal backhaul link or the non-ideal backhaul link. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can be connected to the core network via an ideal backhaul link or a non-ideal backhaul link. Each of the multiple base stations 110-1, 110-2, 110-3, 120-1 and 120-2 can transmit signals received from the core network to the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6, and transmit signals received from the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5 or 130-6 to the core network.

[0060] In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 may support multiple-input multiple-output (MIMO) transmission (e.g., single-user MIMO (SU-MIMO), multi-user MIMO (MU-MIMO), massive MIMO, etc.), coordinated multi-point (CoMP) transmission, carrier aggregation (CA) transmission, transmission in an unlicensed band, device-to-device (D2D) communication (or proximity service (ProSe)), Internet of Things (IoT) communication, dual connectivity (DC), etc. Here, each of the multiple terminals 130-1, 130-2, 130-3, 130-4, 130-5, and 130-6 may perform operations corresponding to the operations of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 (i.e., operations supported by the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2). For example, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 in SU-MIMO mode, and the fourth terminal 130-4 may receive a signal from the second base station 110-2 in SU-MIMO mode. Alternatively, the second base station 110-2 may transmit a signal to the fourth terminal 130-4 and the fifth terminal 130-5 in MU-MIMO mode, and the fourth terminal 130-4 and the fifth terminal 130-5 may receive a signal from the second base station 110-2 in MU-MIMO mode.

[0061] Each of the first base station 110-1, the second base station 110-2, and the third base station 110-3 can transmit a signal to the fourth terminal 130-4 in a CoMP transmission manner, and the fourth terminal 130-4 can receive signals from the first base station 110-1, the second base station 110-2, and the third base station 110-3 in a CoMP manner. In addition, each of the multiple base stations 110-1, 110-2, 110-3, 120-1, and 120-2 can exchange signals with the corresponding terminal 130-1, 130-2, 130-3, 130-4, 130-5, or 130-6 within the coverage area of ​​its cell in a CA manner. Each of base stations 110-1, 110-2, and 110-3 may control D2D communication between fourth terminal 130-4 and fifth terminal 130-5, and thus fourth terminal 130-4 and fifth terminal 130-5 may perform D2D communication under the control of second base station 110-2 and third base station 110-3.

[0062] The parameter sets of physical signals and channels applied to communication systems (e.g., NR communication systems or 6G communication systems) may be variable. The parameter sets may vary to meet various technical requirements of the communication system. In a communication system that applies OFDM waveform technology based on a cyclic prefix (CP), the parameter set may include a subcarrier spacing and a CP length (or CP type). Table 1 below may be a first exemplary embodiment of the configuration of a parameter set for CP-based OFDM. The subcarrier spacing may have an exponential multiplication relationship of 2, and the CP length may be scaled at the same ratio as the OFDM symbol length. Depending on the frequency band in which the communication system operates, at least some of the parameter sets in Table 1 may be supported. In addition, in the communication system, parameter sets not listed in Table 1 may be further supported. For a specific subcarrier spacing (e.g., 60kHz), CP types not listed in Table 1 (e.g., extended CP) may be additionally supported.

[0063] Table 1 relates to a first exemplary embodiment of a method for configuring a parameter set for a CP-OFDM based communication system.

[0064] [Table 1]

[0065]

[0066]

[0067] In the following description, the frame structure in the communication system will be described. In the time domain, the elements constituting the frame structure may include subframes, time slots, micro-time slots, symbols, etc. A subframe may be used as a unit for transmission, measurement, etc., and the length of a subframe may have a fixed value (e.g., 1 ms) regardless of the subcarrier spacing. A time slot may include consecutive symbols (e.g., 14 OFDM symbols). The length of a time slot may vary differently from the length of a subframe. For example, the length of a time slot may be inversely proportional to the subcarrier spacing.

[0068] A time slot can be used as a unit for transmission, measurement, scheduling, resource configuration, timing (for example, scheduling timing, hybrid automatic repeat request (HARQ) timing, channel state information (CSI) measurement and reporting timing, etc.). The length of the actual time resources used for transmission, measurement, scheduling, resource configuration, etc. may not match the length of the time slot. A mini-slot may include consecutive symbols, and the length of a mini-slot may be shorter than the length of a time slot. A mini-slot can be used as a unit for transmission, measurement, scheduling, resource configuration, timing, etc. Mini-slots (for example, the length of mini-slots, mini-slot boundaries, etc.) can be predefined in the technical specifications. Optionally, mini-slots (for example, the length of mini-slots, mini-slot boundaries, etc.) can be configured (or indicated) to the terminal. When specific conditions are met, the use of mini-slots can be configured (or indicated) to the terminal.

[0069] The base station can use some or all of the symbols that make up the time slot to schedule data channels (e.g., physical downlink shared channel (PDSCH), physical uplink shared channel (PUSCH), physical bypass shared channel (PSSCH)). In particular, for URLLC transmission, unlicensed band transmission, transmission in the case of coexistence of NR communication system and LTE communication system, and multi-user scheduling based on analog beamforming, part of the time slot can be used to transmit the data channel. In addition, the base station can use multiple time slots to schedule data channels. In addition, the base station can use at least one mini-time slot to schedule the data channel.

[0070] In the frequency domain, the elements that constitute the frame structure may include resource blocks (RBs), subcarriers, etc. One RB may include consecutive subcarriers (e.g., 12 subcarriers). The number of subcarriers that constitute one RB may be constant, regardless of the parameter set. In this case, the bandwidth occupied by one RB may be proportional to the subcarrier spacing of the parameter set. RBs may be used as transmission and resource allocation units for data channels, control channels, etc. Resource allocation for data channels may be performed in units of RBs or RB groups (e.g., resource block groups (RBGs)). One RBG may include one or more consecutive RBs. Resource allocation for control channels may be performed in units of control channel elements (CCEs). One CCE in the frequency domain may include one or more RBs.

[0071] In a communication system, a time slot (e.g., a time slot format) may consist of a combination of one or more of a downlink period, a flexible period (or an unknown period), and an uplink period. Each of the downlink period, the flexible period, and the uplink period may include one or more consecutive symbols. The flexible period may be located between a downlink period and an uplink period, between a first downlink period and a second downlink period, or between a first uplink period and a second uplink period. When a flexible period is inserted between a downlink period and an uplink period, the flexible period may serve as a guard period.

[0072] The time slot may include one or more flexible time periods. Optionally, the time slot may not include a flexible time period. The terminal may perform predefined operations in the flexible time period. Optionally, the terminal may semi-statically or periodically perform operations configured by the base station. For example, the periodic operations configured by the base station may include PDCCH monitoring operations, synchronization signal / physical broadcast channel (SS / PBCH) block reception and measurement operations, channel state information-reference signal (CSI-RS) reception and measurement operations, downlink semi-persistent scheduling (SPS) PDSCH reception operations, sounding reference signal (SRS) transmission operations, physical random access channel (PRACH) transmission operations, periodically configured PUCCH transmission operations, PUSCH transmission operations according to the configuration permission, etc. Flexible symbols may be covered by downlink symbols or uplink symbols. When a flexible symbol is covered by a downlink symbol or an uplink symbol, the terminal may perform a new operation instead of an existing operation in the corresponding flexible symbol (e.g., the covered flexible symbol).

[0073] In addition, in the present disclosure, a synchronization signal block (SSB) may refer to a signal set including a synchronization signal and / or a broadcast channel. The synchronization signal may include a PSS and an SSS, and the broadcast channel may include a physical broadcast channel (PBCH). The SSB may additionally include a reference signal. The reference signal may represent a demodulation reference signal (DM-RS), a CSI-RS, a tracking reference signal (TRS), a positioning reference signal (PRS), a phase tracking reference signal (PT-RS), etc. for demodulating the PBCH. In an NR communication system, an SSB may refer to a synchronization signal / physical broadcast channel (SS / PBCH) block. The SSB may be transmitted periodically, and one or more SSBs may be repeatedly transmitted in one cycle.

[0074] The format of the unit time resource (hereinafter, "time slot format") can be semi-statically configured by high-layer signaling (e.g., radio resource control (RRC) signaling). Information indicating the semi-static time slot format can be included in the system information, and the semi-static time slot format can be configured in a cell-specific manner. In addition, the semi-static time slot format can be additionally configured for each terminal by terminal-specific high-layer signaling (e.g., RRC signaling). The flexible symbols of the cell-specific configured time slot format can be overwritten by downlink symbols or uplink symbols by terminal-specific high-layer signaling. In addition, the time slot format can be dynamically indicated by physical layer signaling (e.g., a time slot format indicator (SFI) included in downlink control information (DCI)). The semi-statically configured time slot format can be overwritten by a dynamically indicated time slot format. For example, the semi-static flexible symbol can be overwritten by a downlink symbol or an uplink symbol according to the SFI.

[0075] The base station and the terminal can perform downlink operations, uplink operations, and bypass operations in the bandwidth part. A bandwidth part can be defined as a group of consecutive RBs (e.g., physical resource blocks (PRBs)) with a specific parameter set in the frequency domain. The RBs constituting one bandwidth part can be continuous in the frequency domain. One parameter set can be used to transmit a signal (e.g., a control channel or a data channel) in one bandwidth part. In an exemplary embodiment, when used in a broad sense, "signal" can refer to any physical signal and channel. A terminal performing an initial access procedure can obtain configuration information of the initial bandwidth part from the base station through system information. A terminal operating in an RRC connected state can obtain configuration information of the bandwidth part from the base station through terminal-specific high-layer signaling.

[0076] The configuration information of the bandwidth part may include a parameter set applied to the bandwidth part (e.g., subcarrier spacing and CP length). In addition, the configuration information of the bandwidth part may also include information indicating the position of the starting RB (e.g., starting PRB) of the bandwidth part and information indicating the number of RBs (e.g., PRBs) constituting the bandwidth part. At least one bandwidth part among the bandwidth parts configured in the terminal may be activated. For example, within one carrier, one uplink bandwidth part and one downlink bandwidth part may be activated respectively. In a communication system based on time division duplex (TDD), a pair of uplink bandwidth part and downlink bandwidth part may be activated. The base station may configure multiple bandwidth parts to the terminal within one carrier and may switch the active bandwidth part of the terminal.

[0077] In addition, in an exemplary embodiment, "a specific frequency band (e.g., a carrier, a bandwidth portion, a resource block (RB) set, a listen-before-talk (LBT) subband, a guard band, etc.) is activated" may refer to a state in which a base station or terminal can transmit and receive signals using the corresponding frequency band. In addition, "a specific frequency band is activated" may refer to a state in which a radio frequency (RF) filter (e.g., a bandpass filter) of a transceiver operates by including the corresponding frequency band.

[0078] In an exemplary embodiment, an RB may represent a common RB (CRB). Alternatively, an RB may represent a PRB or a virtual RB (VRB). In an NR communication system, a CRB may refer to an RB that constitutes a set of continuous RBs (e.g., a common RB grid) based on a reference frequency (e.g., point A). Carriers, bandwidth parts, etc. may be arranged on a common RB grid. That is, carriers, bandwidth parts, etc. may be composed of CRBs. The RBs or CRBs that constitute the bandwidth part may be referred to as PRBs, and the CRB index within the bandwidth part may be appropriately converted to a PRB index. In an exemplary embodiment, an RB may refer to an interleaved RB (IRB).

[0079] PDCCH can be used to send DCI or DCI format to the terminal. The minimum resource unit constituting PDCCH can be a resource element group (REG). REG can be composed of one PRB (for example, 12 subcarriers) in the frequency domain and one OFDM symbol in the time domain. Therefore, one REG can include 12 resource elements (RE). The demodulation reference signal (DMRS) used to demodulate PDCCH can be mapped to 3 REs of the 12 REs constituting REG, and the control information (for example, modulated DCI) can be mapped to the remaining 9 REs. A PDCCH candidate can consist of one CCE or aggregated CCE. A CCE can be composed of multiple REGs. The NR communication system can support CCE aggregation levels 1, 2, 4, 8, 16, etc., and one CCE can be composed of six REGs.

[0080] A control resource set (CORESET) may be a resource region where a terminal performs blind decoding on a PDCCH. A CORESET may be composed of multiple REGs. A CORESET may be composed of one or more PRBs in the frequency domain and one or more symbols (e.g., OFDM symbols) in the time domain. The symbols constituting a CORESET may be continuous in the time domain. The PRBs constituting a CORESET may be continuous or non-continuous in the frequency domain. One DCI (e.g., one DCI format or one PDCCH) may be sent within one CORESET. Multiple CORESETs may be configured for a cell and a terminal, and multiple CORESETs may overlap in time-frequency resources.

[0081] The CORESET can be configured in the terminal through the PBCH (e.g., system information or master information block (MIB) transmitted on the PBCH). The identifier (ID) of the CORESET configured through the PBCH can be 0. That is, the CORESET configured through the PBCH can be referred to as CORESET#0. A terminal operating in the RRC idle state can perform a monitoring operation in CORESET#0 in order to receive the first PDCCH in the initial access procedure. Not only a terminal operating in the RRC idle state but also a terminal operating in the RRC connected state can perform a monitoring operation in CORESET#0. In addition to the system information transmitted through the PBCH, the CORESET can be configured in the terminal through other system information (e.g., system information block type 1 (SIB1)). For example, in order to receive a random access response (or Msg2) in the random access procedure, the terminal can receive SIB1 including configuration information of the CORESET. In addition, the CORESET can be configured in the terminal through terminal-specific higher layer signaling (e.g., RRC signaling).

[0082] The search space may be a set of PDCCH candidates or a set of resource regions occupied by PDCCH candidates. The terminal may perform blind decoding on each of the PDCCH candidates within the predefined search space. The terminal may determine whether the PDCCH is sent to itself by performing a cyclic redundancy check (CRC) on the result of the blind decoding. When it is determined that the PDCCH is for the terminal itself, the terminal may receive the PDCCH.

[0083] One or more search spaces may constitute a search space set. A search space may be defined / configured for each CCE aggregation level, and a search space set may represent a search space for each CCE aggregation level or a set of search spaces for all CCE aggregation levels. For each CCE aggregation level, a PDCCH candidate may be configured with a CCE selected by a predefined hash function within a CORESET or search space opportunity. In an exemplary embodiment, a "search space set" may refer to a "search space."

[0084] A search space set may be logically associated with one CORESET. A CORESET may be logically associated with one or more search space sets. A search space set used to transmit common DCI or group common DCI may be referred to as a common search space set (hereinafter referred to as a "CSS set"). Common DCI or group common DCI may include at least one of resource allocation information of a PDSCH for transmitting system information, paging, a power control command, an SFI, or a preemption indicator. In the case of an NR communication system, common DCI may correspond to DCI formats 0_0, 1_0, etc., and the cyclic redundancy check (CRC) of the common DCI may be scrambled by system information-radio network temporary identifier (SI-RNTI), paging-RNTI (P-RNTI), random access-RNTI (RA-RNTI), temporary cell-RNTI (TC-RNTI), etc. The group common DCI may correspond to DCI format 2_X (X=0, 1, 2, ...), etc., and the CRC of the group common DCI may be scrambled by a slot format indicator-RNTI (SFI-RNTI), etc. CSS sets may include Type 0, Type 0A, Type 1, Type 2, and Type 3 CSS sets.

[0085] The search space set used to send UE-specific DCI may be referred to as a UE-specific search space set (hereinafter referred to as a "USS set"). The UE-specific DCI may include scheduling and resource allocation information for PDSCH, PUSCH, PSSCH, etc. In the case of an NR communication system, the UE-specific DCI may correspond to DCI formats 0_1, 0_2, 1_1, 1_2, 3_0, 3_1, etc., and the CRC of the UE-specific DCI may be scrambled by C-RNTI, configured scheduling-RNTI (CS-RNTI), modulation and coding scheme-C-RNTI (MCS-C-RNTI), etc. Considering scheduling freedom or fallback transmission, UE-specific DCI may be sent even in the CSS set. In this case, the UE-specific DCI may be sent according to the DCI format corresponding to the common DCI. For example, the terminal may monitor the PDCCH (e.g., DCI format 0_0, 0_1) whose CRC is scrambled with C-RNTI, CS-RNTI, MCS-C-RNTI, etc. in the CSS set.

[0086] The Type 0 CSS set may be used to receive DCI that schedules a PDSCH including SIB1 and may be configured via PBCH or cell-specific RRC signaling. The ID of the Type 0 CSS set may be assigned or set to 0. The Type 0 CSS set may be logically combined with CORESET#0.

[0087] The terminal can improve channel estimation performance or form a transmit / receive beam by using the large-scale propagation characteristics of the radio channel. The large-scale propagation characteristics of the radio channel experienced by the first signal and the second signal transmitted between the communication nodes can be the same. If the large-scale propagation characteristics of the first signal and the second signal sent from the base station to the terminal are the same, a quasi-co-location (QCL) relationship can be established between the first signal and the second signal. In addition, the large-scale propagation characteristics of the radio channel can be defined by QCL parameters. For example, QCL parameters include delay spread, Doppler spread, Doppler shift, average gain, average delay, spatial Rx parameters, etc. Spatial Rx parameters can correspond to the characteristics of the receive beam, receive channel spatial correlation, receive spatial filter, and transmit / receive beam pair. In this disclosure, for convenience, spatial Rx parameters can be referred to as "spatial QCL". A set of one or more QCL parameters can be referred to as a QCL type. The QCL types used in the NR communication system can include at least Type A, Type B, Type C, and Type D. Type D QCL can include spatial Rx parameters and can correspond to spatial QCL.

[0088] The base station may signal the TCI state or TCI to the terminal. In the present disclosure, “TCI state” and “TCI” may be used interchangeably. The TCI state may include information indicating the QCL relationship between a QCL source signal (e.g., a first signal) and a QCL target signal (e.g., a second signal). Specifically, the TCI state may include one or more information indicating the QCL source signal (e.g., the type of source signal, the ID of the source signal, etc.) and information indicating the QCL parameters (e.g., QCL type) for establishing a QCL relationship. In addition, information about the TCI state may be included in the configuration information of the QCL target signal, and the terminal may identify the QCL target signal based on the inclusion relationship. The QCL source signal may include an SSB, a synchronization signal, a reference signal (e.g., CSI-RS, DM-RS), a physical channel, etc. The QCL target signal may include a reference signal, a physical channel, a DM-RS of a physical channel, etc. The QCL source signal and the QCL target signal may be a downlink physical signal or channel or an uplink physical signal or channel. The transmission directions of the QCL source signal and the QCL target signal may be the same or different. The terminal may assume, based on the TCI status signaling information, that the large-scale propagation characteristics of the first signal are equally applied to the second signal.

[0089] A QCL relationship can be established in the PDCCH monitored by the terminal. The terminal can assume that the PDCCH (i.e., PDCCH DM-RS) has a QCL relationship with a certain signal (i.e., a QCL source signal). The QCL relationship can be determined based on the signaling of the above-mentioned TCI state information. Optionally, the QCL relationship can be determined by a method predefined in the technical specification. The terminal can perform beamforming operations, channel estimation operations, etc. based on the QCL relationship for PDCCH monitoring and reception.

[0090] The same TCI or QCL relationship can be applied within a CORESET. That is, the terminal can perform monitoring operations (or reception operations) on all search space sets or all PDCCH candidates belonging to the same CORESET based on the same QCL relationship. The TCI or QCL relationship applied to each CORESET can be configured by the base station or derived through predefined rules. The QCL relationship of a specific CORESET can be determined based on the initial access or random access process of the terminal. For example, CORESET 0 can have a QCL relationship with the SSB selected in the initial access process, the PRACH most recently transmitted in the random access process, etc. When a CORESET pool is configured in the terminal, the same QCL relationship can be established for all CORESETs belonging to the same CORESET pool. Optionally, the TCI or QCL relationship can be applied to each search space set. In this case, different TCIs or different QCL relationships can be applied to monitor multiple search space sets within the same CORESET.

[0091] Link adaptation technology can be used in the communication system. That is, when the sending node wants to send a data channel, a control channel, etc., the sending node can adaptively change the number of transmission layers, modulation and coding (MCS), precoding or beamforming, transmit beam, receive beam, etc. For example, when sending PDSCH to the terminal, the base station can instantly determine the modulation scheme and channel code rate to be applied to the PDSCH, and form one or more transmission layers by applying appropriate precoding to the PDSCH. The above-mentioned link adaptation parameters may be included in the scheduling information of the PDSCH, and may be sent to the terminal when included in the DCI scheduling the PDSCH or included in the semi-persistent scheduling (SPS) configuration information.

[0092] Link adaptation technology can be performed based on the channel state information (CSI) reported from the terminal to the base station. The base station can send a signal (e.g., SSB, CSI-RS, TRS, DM-RS) for the terminal to measure CSI to the terminal. The terminal can receive the signal and calculate the CSI based on the received signal. CSI or CSI type may include channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), layer indicator (LI), beam index, CSI-RS resource indicator (CRI) and SSB resource indicator (SSBRI), etc. In addition, in a broad sense, CSI may include beam quality measurement values ​​(e.g., layer 1-received signal received power (L1-RSRP), layer 1-signal to interference plus noise ratio (L1-SINR)), etc.). The terminal can report the calculated CSI to the base station on an uplink channel (e.g., PUCCH, PUSCH).

[0093] In order to receive a CSI measurement report from a terminal, the base station may send CSI resource configuration information to the terminal. The CSI resource configuration may include configuration information of the CSI-RS resource. For example, the CSI resource configuration may include configuration information about one or more CSI resource sets. The CSI resource set may include a CSI-RS resource set and / or an SSB resource set for channel measurement, and may include a CSI-interference measurement (CSI-IM) resource set for interference measurement. Here, a CSI-RS resource set may refer to a set including one or more CSI-RS resources. If necessary, multiple CSI resource configurations may be configured in the terminal. In an NR communication system, a CSI resource configuration may be referred to as a "CSI resource setting".

[0094] In the present disclosure, CSI-RS resources may refer to physical resources for transmitting CSI-RS. In addition, CSI-RS resources may represent CSI-RS resource configuration parameters or CSI-RS resource configuration units. The terminal may be configured with two types of CSI-RS resources. The first type is non-zero power (NZP) CSI-RS resources, and the second type is zero power (ZP) CSI-RS, wherein, in NZP CSI-RS resources, the base station actually transmits CSI-RS to the terminal, and in ZP CSI-RS, the base station does not actually transmit CSI-RS to the terminal. Hereinafter, unless otherwise specified, CSI-RS resources may be understood to refer to NZP CSI-RS resources. CSI-RS resources may correspond to CSI-RS or CSI-RS sequences.

[0095] CSI-RS resources can be configured as periodic, semi-persistent, or aperiodic. Periodic CSI-RS resources or activated semi-persistent CSI-RS resources can appear periodically and repeatedly, and the location of the resources can be determined by periodicity and offset. Aperiodic CSI-RS resources can be dynamically allocated through DCI. Up to M CSI-RS antenna ports can be mapped to each CSI-RS resource (M is a natural number). In the NR communication system, M can be 32.

[0096] Figure 3 is a conceptual diagram illustrating a first exemplary embodiment of a resource mapping method for CSI-RS antenna ports.

[0097] refer to Figure 3 , the terminal can receive CSI-RS resource configuration information from the base station and receive CSI-RS based on the CSI-RS resource configuration information. The CSI-RS resource can be configured with up to 16 CSI-RS antenna ports. Figure 3 As shown, 16 CSI-RS antenna ports can be mapped within one time slot and one resource block (RB) according to a predetermined pattern. When the CSI-RS transmission bandwidth includes multiple RBs, the CSI-RS can be mapped to multiple RBs in the same pattern. Here, RB can represent a physical resource block (PRB).

[0098] In this exemplary embodiment, it is assumed that the indices (or numbers) of the CSI-RS antenna ports are assigned in ascending order starting from 0. Therefore, the 16 CSI-RS antenna ports can be assigned indices from 0 to 15. However, the index is merely an identifier for distinguishing different CSI-RS antenna ports, and numbers other than 0 to 15 may also be used. For example, in an NR communication system, the indices of the CSI-RS antenna ports may be assigned in ascending order starting from 3000. Figure 3The indices 0 to 15 shown in FIG. 3 may correspond to indices 3000 to 3015 in the NR communication system. Antenna port numbers of CSI-RS antenna ports for determining CSI (eg, PMI), which will be described later, may be reallocated as consecutive values ​​in ascending order starting from P (P is an integer, for example, P=3000).

[0099] CSI-RS antenna ports may be mapped to resource elements (REs) when multiplexed in the form of time division multiplexing (TDM), frequency division multiplexing (FDM), and / or code division multiplexing (CDM).

[0100] refer to Figure 3 , TDM, FDM, and CDM can all be applied to the multiplexing of 16 CSI-RS antenna ports. For example, CSI-RS antenna ports 0 to 3 can be mapped to the fifth to sixth symbols and the third to fourth subcarriers, CSI-RS antenna ports 4 to 7 can be mapped to the fifth to sixth symbols and the ninth to tenth subcarriers, CSI-RS antenna ports 8 to 11 can be mapped to the ninth to tenth symbols and the third to fourth subcarriers, and CSI-RS antenna ports 12 to 15 can be mapped to the ninth to tenth symbols and the ninth to tenth subcarriers. In this case, CSI-RS antenna ports 0 to 3 and CSI-RS antenna ports 4 to 7 can be FDMed in the same symbol. In addition, CSI-RS antenna ports 0 to 3 and CSI-RS antenna ports 8 to 11 can be TDMed in the same subcarrier. In addition, the four CSI-RS antenna ports mapped to four adjacent REs can be CDMed and form a CDM group. For example, CSI-RS antenna ports 0 to 3, CSI-RS antenna ports 4 to 7, CSI-RS antenna ports 8 to 11, and CSI-RS antenna ports 12 to 15 may form CDM group 0, CDM group 1, CDM group 2, and CDM group 3, respectively.

[0101] Multiple CDMA antenna ports can be distinguished by different orthogonal cover codes (OCCs). The four different CSI-RS antenna ports of a CDM group of size 4 can be distinguished from each other by a time domain (TD)-OCC of length 2 and a frequency domain (FD)-OCC of length 2. The order in which the CSI-RS antenna ports are mapped to the CSI-RS REs may conform to a predefined rule. In this exemplary embodiment, the indexes of the CSI-RS antenna ports are first allocated within the CDM group, then allocated in ascending order in the frequency domain (i.e., in the direction of increasing subcarrier index), and finally allocated in ascending order in the time domain (i.e., in the direction of increasing symbol index).

[0102] Figure 3The CSI-RS mapping pattern shown in is merely an exemplary embodiment, and CSI-RS resource mapping can be implemented in various forms. The terminal can receive configuration information related to the number of CSI-RS antenna ports constituting the CSI-RS resource, the size of each CDM group, the number of CDM groups, the position of each CDM group, the frequency domain CSI-RS transmission density, the time domain period, the offset, etc. from the base station, determine the mapping position of each CSI-RS antenna port in the CSI-RS resource based on the configuration information, and receive each CSI-RS antenna port at the identified mapping position. The base station can also map the CSI-RS antenna port to the CSI-RS resource based on the configuration information and send the CSI-RS antenna port to the terminal. In the following, a terminal receiving a CSI-RS antenna port can be interpreted as having the same meaning as a terminal receiving a CSI-RS through the corresponding CSI-RS antenna port. In addition, a base station transmitting a CSI-RS antenna port can be interpreted as having the same meaning as a base station transmitting a CSI-RS through the corresponding CSI-RS antenna port.

[0103] The base station's transmit signal can be processed by a transceiver unit (TXRU), and the processed output signal can be beamformed by an antenna module including physical antenna elements and radiated into space when converted into electromagnetic waves. The TXRU of the signal transmitter can also be referred to as a transmitter unit (TXU), a radio frequency (RF) chain, etc. The TXRU and the physical antenna elements can be mapped to each other in a pre-implemented manner to adapt to the desired beam shape, and the mapping can be controlled and changed by the base station if necessary. Such mapping can be called antenna virtualization.

[0104] According to the above operations, each CSI-RS antenna port constituting a CSI-RS resource can be mapped to one or more TXRUs. In addition, through TXRU-physical antenna element mapping, each CSI-RS antenna port can be mapped to one or more physical antenna elements.

[0105] Figure 4 is a conceptual diagram illustrating a first exemplary embodiment of a mapping method between CSI-RS antenna ports and TXRUs or physical antenna elements.

[0106] refer to Figure 4, a two-dimensional planar antenna panel can be used for signal transmission, and the two-dimensional planar antenna panel can be composed of physical antenna elements arranged to have cross-polarization. The physical antenna elements can be arranged on a two-dimensional plane consisting of a first direction (e.g., horizontal direction) and a second direction (e.g., vertical direction), and each physical antenna element can be arranged to have a first polarization or a second polarization. In addition, each TXRU can be mapped to a physical antenna element with a specific polarization. For convenience, a TXRU mapped to a physical antenna element with a first polarization (or a second polarization) can be referred to as a TXRU with a first polarization (or a second polarization).

[0107] The base station can send CSI-RS resources configured with 16 CSI-RS antenna ports to the terminal. The 16 CSI-RS antenna ports can be mapped to 32 TXRUs. Figure 4 As shown, among the 32 TXRUs, 16 TXRUs may have a first polarization and the remaining 16 TXRUs may have a second polarization. In this case, each CSI-RS antenna port may be mapped to two TXRUs having the same polarization and adjacent in the second direction (e.g., vertical direction). The order in which the CSI-RS antenna ports are mapped in the first domain (e.g., horizontal domain), the second domain (e.g., vertical domain), and the polarization domain may be determined based on the CSI codebook structure used for PMI feedback. For example, when a dual codebook W applied to a polarized antenna and having a structure of W=W1*W2 is used, the CSI-RS antenna ports may be indexed first in ascending order in the second domain (e.g., vertical domain), secondly in ascending order in the first domain (e.g., horizontal domain), and finally in ascending order in the polarization domain. As a result, CSI-RS antenna ports 0 to 7 may be respectively mapped to two TXRUs having the first polarization, and CSI-RS antenna ports 8 to 15 may be respectively mapped to two TXRUs having the second polarization. In this exemplary embodiment, the TXRU can be considered as a physical antenna element. That is, Figure 4 The concept shown in can be interpreted as 16 CSI-RS antenna ports being mapped to 32 physical antenna elements. In this case, the mapping relationship related to the TXRU can be defined separately. For example, the TXRU and the physical antenna elements can have a one-to-one correspondence. Alternatively, the CSI-RS antenna ports and the TXRU can have a one-to-one correspondence.

[0108] In addition, the CSI reporting (or CSI feedback) operation of the terminal can be performed based on the CSI reporting configuration configured by the base station. The CSI reporting configuration may include configuration information related to the type (or reporting amount) of CSI to be reported by the terminal to the base station, the frequency range of CSI, whether CSI is for wideband or narrowband, time domain periodicity, CSI codebook, etc. The CSI reporting operation can be performed periodically, semi-persistently, or aperiodically. The CSI report can be sent on the PUCCH or PUSCH. The CSI reporting configuration may be associated with the CSI resource configuration. The terminal may perform CSI calculation operations based not only on the CSI resource configuration but also on the CSI reporting configuration associated with the CSI resource configuration. In the NR communication system, the CSI reporting configuration may be referred to as a "CSI reporting setting".

[0109] In addition, as communication systems become more complex, technologies for improving network power efficiency are attracting attention. The network (i.e., base station) can choose to enter sleep mode, wherein, in sleep mode, it does not perform transmit / receive operations, or operates in low power mode by using only part of the transceiver to perform transmit / receive operations, and thus can reduce the power consumption of the network. In the present disclosure, a method for dynamic scaling of spatial elements will be described as a method for reducing power consumption in the spatial domain. Here, spatial elements can be used to refer to antenna ports (e.g., CSI-RS antenna ports), TXRUs, RF chains, physical antenna elements, antenna panels, etc.

[0110] As a method for scaling spatial elements, it is possible to consider silencing some spatial elements. For example, the base station may dynamically silence or turn off some of the TXRUs in a certain period of time, and only use the TXRUs that are not silenced or turned on to send signals. In this case, the operation of silencing the TXRUs may include silencing the physical antenna elements to which the TXRUs are mapped. Alternatively, the base station may dynamically silence some of the physical antenna elements without silencing the TXRUs in a certain period of time, and only use the physical antenna elements that are not silenced to send signals. According to the above method, the base station can maximize the spatial multiplexing gain by driving all TXRUs in a period of high traffic (hereinafter referred to as the "first period"), and can operate in low power mode by driving a small number of TRXUs in a period of low traffic (hereinafter referred to as the "second period"). Therefore, the power efficiency of the network can be improved without losing transmission capacity.

[0111] As described above, CSI-RS antenna ports can be mapped to TXRUs. Therefore, when performing a TXRU muting operation, the CSI-RS antenna ports corresponding to the muted TXRUs can also be muted according to the mapping scheme or muting pattern. This will be described in detail in the following exemplary embodiments.

[0112] Figure 5a is a conceptual diagram illustrating a first exemplary embodiment of a TXRU quiescing method, and Figure 5b is a conceptual diagram illustrating a second exemplary embodiment of a TXRU silencing method.

[0113] refer to Figure 5a and Figure 5b ,and Figure 4 As in the first exemplary embodiment, 32 TXRUs with first and second polarizations can be arranged in a two-dimensional space. In this disclosure, "TXRUs are arranged in space" may mean "physical antenna elements to which the TXRUs are mapped are arranged in space." In addition, each CSI-RS antenna port can be mapped to two TXRUs with the same polarization and adjacent in the vertical direction. In this case, some TXRUs can be silenced using the above method.

[0114] exist Figure 5a In the first exemplary embodiment, 16 TXRUs in the third and fourth rows may be muted. The base station may use the remaining 16 TXRUs to transmit signals. In the case of CSI-RS transmission, 8 CSI-RS antenna ports may be mapped to the remaining 16 TXRUs, and the CSI-RS antenna ports may be transmitted to the terminal. Figure 4 Compared to the first exemplary embodiment, 8 of the 16 CSI-RS antenna ports can be considered to be muted. Although the number of CSI-RS antenna ports is scaled, assuming the same antenna virtualization scheme, the beam pattern formed by each CSI-RS antenna port can be maintained (i.e., the TXRU connected to each CSI-RS antenna port is maintained unchanged). The above method can be referred to as the "first TXRU muting method."

[0115] exist Figure 5b In the second exemplary embodiment, 16 TXRUs in the second and fourth rows may be muted. The base station may use the remaining 16 TXRUs to transmit signals. In the case of CSI-RS transmission, 16 CSI-RS antenna ports may be mapped to the remaining 16 TXRUs, and the CSI-RS antenna ports may be transmitted to the terminal. Figure 4Compared with the first exemplary embodiment of TXRU muting pattern, it can be confirmed that the number of CSI-RS antenna ports available for transmission is not affected by TXRU muting. However, the number of TXRUs mapped to each CSI-RS antenna port is reduced from 2 to 1, so even if the same antenna virtualization scheme is assumed, the beam pattern formed by each CSI-RS antenna port may change. The above method can be referred to as the "second TXRU muting method".

[0116] Hereinafter, the adaptive scaling or muting method of the CSI-RS antenna port will be described in more detail.

[0117] Figure 6 is a conceptual diagram illustrating a first exemplary embodiment of a CSI reporting method based on multiple CSI-RS antenna port sets.

[0118] refer to Figure 6 , the terminal can receive the configuration information of CSI-RS resources from the base station. t = 16 CSI-RS antenna ports. CSI-RS resources may appear periodically and repeatedly.

[0119] According to the proposed method, the terminal may additionally receive first configuration information from the base station and configure multiple (or more than one) CSI-RS antenna port sets based on the first configuration information. Here, the first configuration information may be configuration information of the CSI-RS antenna port set. As will be described later, the first configuration information may be replaced with codebook configuration information or may be regarded as codebook configuration information. In addition, the first configuration information may be sent separately and may be sent when included in the configuration information of the CSI-RS resource or included in the CSI report configuration information. Each CSI-RS antenna port set may be configured as L t =At least a portion (i.e., a subset) of 16 CSI-RS antenna ports. That is, multiple CSI-RS antenna port sets can be derived within the same CSI-RS resource. In this exemplary embodiment, the terminal can configure the first CSI-RS antenna port set and the second CSI-RS antenna port set based on the first configuration information. The first CSI-RS antenna port set may include L1=L t = 16 CSI-RS antenna ports, and the second CSI-RS antenna port set may include L2 = 4 CSI-RS antenna ports. L2 = 4 CSI-RS antenna ports may be L t=A portion of 16 CSI-RS antenna ports. For example, each CSI-RS antenna port set may be referred to as a CSI-RS subresource, a CSI-RS resource subconfiguration, etc., and may be configured as a subparameter of a CSI-RS resource in the terminal. In the present disclosure, each CSI-RS antenna port set (or subset) may correspond to each spatial element pattern. In addition, the above-mentioned multiple CSI-RS antenna port sets configured by one CSI-RS resource are merely exemplary embodiments, and as will be described later, multiple CSI-RS antenna port sets may be configured by multiple CSI-RS resources. In this case, each CSI-RS antenna port set may correspond to each CSI-RS resource. Multiple CSI-RS resources may belong to the same CSI-RS resource set.

[0120] The terminal may receive CSI report configuration information from the base station and perform a CSI reporting operation. The terminal may report multiple CSIs to the base station. The multiple CSIs may correspond to multiple CSI-RS antenna port sets (i.e., multiple spatial element patterns), respectively. In this exemplary embodiment, the CSI report of the terminal may include a first CSI and a second CSI. The first CSI may be a CSI calculated based on a first CSI-RS antenna port set (i.e., 16 received CSI-RS antenna ports), and the second CSI may be a CSI calculated based on a second CSI-RS antenna port set (i.e., L2=4 CSI-RS antenna ports among the received 16 CSI-RS antenna ports). As described above, each of the first CSI and the second CSI may include CQI, PMI, RI, LI, CRI, SSBRI, beam quality measurement, etc. The above method may be referred to as (method 100).

[0121] Multiple CSIs can be sent to a base station based on one CSI reporting configuration. For example, a CSI reporting configuration may include multiple CSI reporting subconfigurations. Each CSI reporting subconfiguration may include configuration information for reporting each CSI derived based on each CSI-RS antenna port set. In other words, each CSI reporting subconfiguration may correspond to each CSI-RS antenna port set (or each spatial element pattern). Multiple CSIs may be sent together through the same uplink transmission (e.g., PUCCH, PUSCH). The above method may be referred to as a first CSI reporting method or a multiple CSI reporting method. Alternatively, multiple CSIs may be sent to a base station based on multiple CSI reporting configurations. For example, each CSI reporting configuration may include configuration information for reporting each CSI derived based on each CSI-RS antenna port set. In this case, multiple CSIs may be sent at different transmission times using different uplink resources. Alternatively, even in this case, multiple CSIs may be sent at the same transmission time using the same uplink resource. The above method may be referred to as a second CSI reporting method or a single CSI reporting method.

[0122] In the first CSI reporting method, the number of CSI report subconfigurations belonging to the CSI report configuration may be referred to as A. In addition, the number of CSI-RS antenna port sets configured for spatial element adaptation operation (e.g., CSI-RS antenna port sets belonging to one CSI-RS resource or one CSI-RS resource set) may be referred to as B. A CSI-RS resource or a CSI-RS resource set may be associated with a CSI report configuration. In this case, each CSI report subconfiguration may correspond to one or up to one CSI-RS antenna port set, and generally A may have a value equal to or less than B. That is, the CSI report of the terminal may include a CSI report for each of all spatial element patterns configured in the terminal, or may include CSI reports for some of the spatial element patterns configured in the terminal. In an exemplary embodiment, A may be 1. This case may correspond to the second CSI reporting method. In an exemplary embodiment, B may be 1. This case may correspond to a conventional CSI-RS transmission method in which the CSI-RS antenna port adaptation technology is not applied.

[0123] The terminal may send all A CSI reports corresponding to A CSI report sub-configurations to the base station. Optionally, for the purpose of reducing uplink control information (UCI) overhead, the terminal may determine A1 CSI report sub-configuration among the A CSI report sub-configurations, and send A1 CSI reports for the determined A1 CSI report sub-configuration to the base station (where A1 is a natural number less than or equal to A). The A1 CSI report sub-configuration may be determined based on the configuration information received from the base station. Depending on the periodicity of the configured CSI report, the above-mentioned CSI overhead reduction technique may be applied or not applied. In addition, the above-mentioned CSI overhead reduction technique may be configured to the terminal based on different signaling procedures according to the periodicity of the configured CSI report. For example, the configuration information may be included in an RRC message and may be sent when included in the CSI report configuration information including the CSI report sub-configuration, or may be sent together with the CSI report configuration information.

[0124] Additionally or optionally, A1 CSI report subconfigurations may be dynamically indicated to the terminal based on a physical layer signaling process. The base station may indicate the CSI report subconfiguration to be reported by the terminal through DCI. For example, the DCI may be a group-common DCI. That is, a DCI including information about the CSI report subconfiguration may be sent to a terminal group, and the terminal receiving the DCI may change or maintain the CSI reporting operation based on the indication information included in the DCI. The indication information included in the group-common DCI may be information common to all terminals receiving the group-common DCI. Optionally, the group-common DCI may include multiple indication information for multiple terminals or multiple terminal groups (or subgroups) receiving the group-common DCI. The multiple indication information may correspond to different fields or different bits (or bit strings) within the same field. In order to monitor the group-common DCI, the base station may configure a type 3 CSS set, a group-common RNTI, etc. to the terminal.

[0125] As another example, the DCI may be a scheduling DCI. For example, a CSI reporting operation for a CSI reporting subconfiguration may be triggered aperiodically by a scheduling DCI. In this case, the scheduling DCI may include indication information about the CSI reporting subconfiguration, and the terminal may determine the A1 CSI reporting subconfiguration to be reported to the base station based on the indication information, and perform an operation of reporting an aperiodic CSI report including the corresponding A1 CSI. The indication information may also include other information necessary to perform the aperiodic CSI reporting operation. For example, the indication information may include uplink TCI, uplink spatial relationship information, etc., for forming a transmit beam for an uplink signal through which the aperiodic CSI report is to be sent. In addition, the indication information may include information about the uplink resources in which the aperiodic CSI report is to be sent.

[0126] Optionally, a CSI reporting operation for a CSI reporting subconfiguration may be performed semi-persistently or periodically. The base station may instruct the terminal to activate or deactivate the CSI reporting operation through DCI (e.g., scheduling DCI) or MAC layer signaling (e.g., MAC CE). In this case, the DCI or MAC layer signaling may include indication information about the CSI reporting subconfiguration and activation indication information of the CSI reporting operation, and the terminal may perform an operation of reporting a semi-persistent CSI report including the indicated CSI reporting subconfiguration. A predetermined time gap (e.g., a time slot offset and / or a symbol offset) may be ensured between the time (e.g., time slot, symbol) at which the terminal performs a CSI report sending operation reflecting a dynamically indicated CSI reporting subconfiguration and the time (e.g., time slot, symbol) at which the terminal receives a dynamic indication (e.g., DCI, MAC CE). As described above, if the CSI reporting subconfiguration corresponds to a CSI-RS antenna port set (or spatial element pattern), the above method may correspond to the operation to be described later, i.e., a method of dynamically indicating some CSI-RS antenna port sets through DCI.

[0127] As another method, the terminal may autonomously select A1 CSI reporting subconfiguration. For example, the terminal may select A1 CSI reports (or corresponding CSI reporting subconfiguration) that provide the highest channel quality. Channel quality may be determined based on metrics defined in technical specifications (e.g., CQI, etc.). In an exemplary embodiment, A1 may be 1. In this case, the first CSI reporting method may correspond to a CSI reporting operation including a single CSI, and UCI overhead may be kept low.

[0128] When the terminal uses the above method to report multiple CSIs for multiple spatial element patterns, the multiple CSIs can be associated with each other. That is, the CSI for one spatial element pattern can be calculated based on the CSI for another spatial element pattern. For example, the terminal can report the first CSI and the second CSI for the first CSI-RS antenna port set and the second CSI-RS antenna port set to the base station respectively. The first CSI and the second CSI can be reported based on the first CSI reporting subconfiguration and the second CSI reporting subconfiguration respectively. In this case, the first CSI can be determined based on the second CSI. Optionally, the second CSI can be determined based on the first CSI. For example, the first CQI derived based on the first CSI-RS antenna port set can be a differential CQI expressed as a difference from the second CQI derived based on the second CSI-RS antenna port set. For another example, the first PMI or RI derived based on the first CSI-RS antenna port set can be a differential PMI or RI expressed as a difference from the second PMI or RI derived based on the second CSI-RS antenna port set. In this case, the second CQI may have a value (or index) corresponding to a higher quality than the first CQI. In addition, the CQI derived based on the second PMI and / or the second RI may have a value (or index) corresponding to a higher quality than the CQI derived based on the first PMI and / or the first RI. Differential CSI can be represented by fewer bits, and the CSI payload can be reduced by the above method. When CSI is transmitted on PUCCH, the size of the resource to which the PUCCH is mapped (e.g., the number of PRBs) can be reduced as the total payload size of the CSI to be transmitted on the PUCCH decreases, and the PUCCH format used therefor may also be changed. The above operation can be performed only when the first CSI reporting method is used. That is, multiple CSIs may correspond to CSI reporting subconfigurations belonging to one CSI reporting configuration.

[0129] As another method for reducing CSI overhead, the terminal may report A2 CSIs representing A CSI reporting subconfigurations or the selected A1 CSI reporting subconfiguration to the base station. A2 may be a natural number equal to or less than A or A1. The A2 CSIs may be calculated based on the A CSI reporting subconfigurations or the selected A1 CSI reporting subconfiguration. Alternatively, the terminal may select A2 CSI reporting subconfiguration from the A or A1 CSI reporting subconfiguration and calculate the A2 CSI based on the selected A2 CSI reporting subconfiguration.

[0130] In an exemplary embodiment, A2 may be 1. For example, the terminal may derive one CSI (e.g., CQI, PMI, RI, CRI, SSBRI, and / or L1-RSRP) for A or A1 CSI reporting subconfigurations, and may report the one CSI to the base station. One CSI may be a value derived based on one CSI reporting subconfiguration. For example, the terminal may calculate CSI for each of multiple CSI reporting subconfigurations, select one CSI (e.g., the best CSI) from the calculated CSIs, and report the selected one CSI. One CSI may represent the channel quality corresponding to the best spatial element pattern (i.e., the best CSI-RS antenna port muting pattern). Alternatively, one CSI may be a value (e.g., a joint coding value) derived based on multiple CSI reporting subconfigurations (i.e., multiple CSI-RS antenna port muting patterns). The CSI may include information about which CSI reporting subconfiguration the CSI is based on. For example, the information may include an index (or number) of the CSI reporting subconfiguration on which the CSI is based. For example, this information may be referred to as a sub-configuration indicator, a CSI report sub-configuration indicator, or the like. This information can be distinguished from CRI. In other words, CRI refers to information about the CSI-RS resources that a terminal wishes to selectively report within a given sub-configuration (e.g., a CSI-RS resource index), while a sub-configuration indicator refers to information about the sub-configuration that a terminal wishes to selectively report. Typically, when A2 CSIs are reported, the corresponding A2 sub-configuration indicators may be reported together.

[0131] In another exemplary embodiment, A2 may be A1. For example, the terminal may calculate A1 CSI based on the configured A CSI reporting subconfigurations, or may select A1 CSI reporting subconfiguration from the A CSI reporting subconfigurations, calculate A1 CSI based on the selected A1 CSI reporting subconfiguration, and report the A1 CSI to the base station.

[0132] In the above method, the number of reported CSI types may be different for each CSI type. A terminal's CSI report for A or A1 CSI reporting subconfigurations may include A2 specific CSI types and A or A1 other CSI types. For example, a terminal's CSI report may include one CQI and as many other CSI types (e.g., PMI, RI, CRI, SSBRI, etc.) as the number of CSI reporting subconfigurations (i.e., A or A1). The one CQI may be the (best) CQI selected from multiple CQIs derived for multiple CSI reporting subconfigurations.

[0133] When the terminal reports multiple CSIs based on the second CSI reporting method, the above-mentioned CSI overhead reduction technique can also be applied. For example, the terminal can be configured with a first CSI reporting configuration and a second CSI reporting configuration. The first CSI calculated based on the first CSI-RS antenna port set can be reported according to the first CSI reporting configuration, and the second CSI calculated based on the second CSI-RS antenna port set can be reported according to the second CSI reporting configuration. The transmission timing (e.g., transmission time slot) and / or transmission resources (e.g., PUCCH, PUSCH) of the first CSI and the second CSI can overlap.

[0134] In this case, the CSI reporting operation for the first CSI reporting configuration and the second CSI reporting configuration can be performed based on the above-mentioned CSI overhead reduction technique. For example, the first CSI can be determined based on the second CSI. For another example, one of the first CSI and the second CSI can be selected, and the selected CSI can be reported to the base station. Optionally, a CSI (e.g., a unified CSI) can be jointly calculated based on both the first CSI reporting configuration and the second CSI reporting configuration, and the one CSI can be reported to the base station. In this case, multiple CSI reporting configurations can be configured to have the same time characteristics. For example, if the first CSI reporting configuration is configured periodically, semi-persistently, or aperiodically, the second CSI reporting configuration can also be configured periodically, semi-persistently, or aperiodically. The terminal may not expect to be instructed to apply the above-mentioned CSI overhead reduction technique to multiple CSI reporting configurations with different time characteristics.

[0135] In the case of aperiodic CSI reporting, the DCI triggering the aperiodic CSI reporting may include information indicating the CSI reporting configuration to be processed and transmitted together (e.g., a CSI reporting configuration index), and the terminal may perform CSI reporting operations based on the above-mentioned method for the indicated CSI reporting configuration. In the case of semi-persistent CSI reporting, the DCI or MAC CE indicating the activation of semi-persistent CSI reporting may include information indicating the CSI reporting configuration to be processed and transmitted together (e.g., a CSI reporting configuration index), and the terminal may perform CSI reporting operations based on the above-mentioned method for the indicated CSI reporting configuration.

[0136] In addition, the reporting timing (e.g., transmission time slot) of the first CSI may not match the reporting timing (e.g., transmission time slot) of the second CSI. Even in this case, the above-mentioned CSI processing and reporting operations can be performed in the same manner. However, the timing for sending the finalized CSI to the base station can be determined by rules predefined in the technical specifications. For example, the final CSI can be sent in one of the transmission time slot of the first CSI and the transmission time slot of the second CSI (e.g., a later time slot or an earlier time slot). For another example, the final CSI can be sent in a time slot other than the transmission time slot of the first CSI and the transmission time slot of the second CSI. Taking into account the time required to calculate the final CSI, the time slot can be a time slot that is no earlier than the transmission time slot of the first CSI and the transmission time slot of the second CSI. The base station can configure the time slot in which the final CSI is to be sent to the terminal. For example, the time slot offset between the time slot in which the final CSI is to be sent and the transmission time slot of the first CSI or the second CSI can be indicated to the terminal.

[0137] In addition, when the terminal calculates multiple CSIs for multiple spatial element patterns and reports them to the base station, the CSI calculation complexity may increase. The CSI calculation capability of the terminal can be indicated by the CSI processing unit (CPU). The terminal can process up to N_CPU CSIs at a time (for example, in a specific symbol) and report N_CPUs as the terminal's capability to the base station. In this case, it can be said that the terminal has N_CPU CPUs for CSI reporting operations. Typically, one CSI-RS resource referenced by the CSI report can occupy one CPU.

[0138] When the above-mentioned network power reduction method is used, one CSI-RS resource can be referenced by one CSI report configuration, and the one CSI report configuration can be associated with A or selected A1 CSI report subconfigurations. In this case, one CSI-RS resource can be referenced by A or selected A1 CSI report subconfigurations belonging to one CSI report configuration. The terminal can calculate A1 (or A2 further selected by the above method) CSIs corresponding to different spatial element patterns (for example, different CSI-RS antenna port sets) based on one CSI-RS resource. Therefore, the CSI calculation complexity of the terminal based on one CSI-RS resource can correspond to the CSI calculation complexity based on A1 (or A2) CSI-RS resources. Therefore, one CSI-RS resource can occupy A1 (or A2) CPUs. Optionally, one CSI-RS resource can be counted A1 times. Optionally, one CSI-RS resource can be regarded as A1 (or A2) active CSI-RS resources. Alternatively, one CSI-RS resource may be considered as Ar active CSI-RS resources. Ar may be determined as one of values ​​between 1 and A1 (or A2). In an exemplary embodiment, Ar may be a natural number.

[0139] Additionally, the CSI calculation complexity of the terminal can be limited to the number of active CSI-RS antenna ports. In the above case, the number of active CSI-RS antenna ports for one CSI-RS resource can be regarded as the total number of CSI-RS antenna ports corresponding to A1 (or A2) CSI reporting sub-configurations that reference one CSI-RS resource. That is, one CSI-RS antenna port constituting a CSI-RS resource can be counted redundantly. For example, under the above configuration, one CSI-RS antenna port constituting a CSI-RS resource can correspond to the number of A1 (or A2) active CSI-RS antenna ports. The terminal can send information about the number of active CSI-RS antenna ports that it can process simultaneously at one time to the base station as capability information of the terminal.

[0140] If the number K of CPUs configured to be processed by the terminal at a specific time (e.g., a specific symbol) exceeds N_CPU, the terminal may not calculate or report CSI for the redundant part to the base station. When the K CPUs include the CPU for the above-mentioned CSI-RS resource, the terminal may select some CSI reporting subconfigurations from multiple CSI reporting subconfigurations that reference the CSI-RS resource according to the priority rule, and perform a CSI reporting operation for the selected CSI reporting subconfiguration. In this case, the CSI reporting operation for the remaining CSI reporting subconfigurations may be omitted. For example, a higher priority may be assigned to a CSI reporting subconfiguration with a lower (or higher) index. According to the above operation, the terminal may report only some of the multiple CSIs associated with the same CSI-RS resource to the base station. Multiple CSIs may correspond to multiple CSI reporting subconfigurations, respectively.

[0141] In addition, a CSI reporting configuration may reference multiple CSI-RS resources, and the CSI for one of the multiple CSI-RS resources and the ID of the one CSI-RS resource (i.e., CSI-RS Resource Indicator (CRI)) may be reported from the terminal to the base station. Similarly, each CSI-RS resource may be associated with multiple CSI reporting subconfigurations. Even in this case, the CSI reporting operation of the terminal within its CSI processing capability may be performed based on the priority between the CSI reporting subconfigurations, and the priority may be assigned in ascending or descending order of the CSI reporting subconfiguration index. When the number of CSI reporting subconfigurations and the number of CSI-RS resources associated with the CSI reporting subconfiguration are P and Q, respectively, the number of CPUs corresponding to the CSI reporting operation may be P*Q. When the number of CSI reporting subconfigurations selected by priority is P1, the corresponding CPUs may be reduced to P1*Q. The terminal may sequentially include the CSI reporting subconfigurations in the measurement and reporting targets one by one based on the CSI reporting subconfiguration index until P1*Q does not exceed N_CPU.

[0142] In the above case, that is, when each CSI report subconfiguration is associated with multiple CSI-RS resources, the terminal can select one CSI-RS resource associated with each CSI report subconfiguration and can report the CSI for the selected CSI-RS resource to the base station. Here, according to the TXRU muting scheme, all CSI report subconfigurations can be associated with the same CSI-RS resource, or each CSI report subconfiguration can be associated with a different CSI-RS resource. In this case, the CSI may include a CRI, and the CRI may include information indicating the selected CSI-RS resource (e.g., an index). If the number of subconfigurations configured or activated for one CSI report is A (or A1), the number of reported CSIs may also be A (or A1). In this case, the A (or A1) CRIs corresponding to the A (or A1) subconfigurations may all be the same. That is, the terminal may select a common CSI-RS resource for multiple subconfigurations and calculate and report the CSI for the selected CSI-RS resource for each subconfiguration. In this case, the CRI corresponding to the common CSI-RS resource may be included and transmitted in each CSI. That is, the CRI may be transmitted repeatedly A times (or A1 times). Alternatively, to reduce the CSI payload, the CRI may be transmitted once without redundancy. In this case, the CRI may be included in the CSI for one subconfiguration. One subconfiguration may be predefined in the technical specification. For example, the CRI may be transmitted and included in the CSI for the subconfiguration with the lowest (or highest) subconfiguration index. The CRI may be CSI of high priority or importance, and therefore, it may be considered as the payload of CSI part 1.

[0143] As another method, A (or A1) CRIs corresponding to A (or A1) sub-configurations can be determined independently of each other. That is, the terminal can select CSI for different CSI-RS resources for multiple sub-configurations and report them to the base station. According to the above method, the terminal can select the CSI with the highest channel quality and the corresponding CSI-RS resource for each CSI reporting sub-configuration, and the information about them can be shared with the base station and used for scheduling.

[0144] In (method 100), the base station can transmit the CSI-RS antenna ports constituting the CSI-RS antenna port subset among the CSI-RS antenna ports constituting the CSI-RS resource, that is, at least the CSI-RS antenna ports required for the CSI calculation of the terminal. If there are remaining CSI-RS antenna ports that the terminal does not receive (or does not actually use even if received), they do not necessarily need to be transmitted. In this exemplary embodiment, since the first CSI-RS antenna port set includes all CSI-RS antenna ports constituting the CSI-RS resource, the base station can transmit all L in the CSI-RS resource of each period. t (=16) CSI-RS antenna ports. The terminal can receive all L t (=16) CSI-RS antenna ports and calculate the first CSI and the second CSI.

[0145] The base station can perform adaptive downlink scheduling based on multiple CSIs reported from the terminal. Figure 6 , the base station can use multiple TXRUs (for example, 32 TXRUs) to send PDSCH based on the first CSI in a first time period with high traffic. The downlink transmission performance can be maximized in the first time period. Additionally, the base station can use a small number of TXRUs (for example, 4 TXRUs) to send PDSCH based on the second CSI in a second time period with low traffic. The network power efficiency can be improved in the second time period. According to (method 100), unlike the data channel transmission period, the number of TXRUs used in the CSI-RS transmission period (for example, the symbol for transmitting CSI-RS, the time slot for transmitting CSI-RS, etc.) can be fixed. In this exemplary embodiment, the base station can send L in the CSI-RS resources of each cycle. t = 16 CSI-RS antenna ports, and therefore, corresponding 32 TXRUs can operate in the CSI-RS transmission period.

[0146] Figure 7 is a conceptual diagram illustrating a first exemplary embodiment of a method for configuring multiple CSI-RS antenna port sets.

[0147] In this exemplary embodiment, the mapping operation between CSI-RS antenna ports, TXRUs, and physical antenna elements may follow Figure 4 The operation described in the first exemplary embodiment of FIG. Figure 7 , the first CSI-RS antenna port set may include all L1=L t = 16 CSI-RS antenna ports, and these can be mapped to all 32 TXRUs. For example, a terminal can receive Figure 3, and derive the first CSI based on the CSI codebook corresponding to the received 16 CSI-RS antenna ports. The CSI codebook can be a two-dimensional (2D) codebook of size (N1, N2) = (4, 2) or (N1, N2, P) = (4, 2, 2). Here, N1, N2, and P can represent the number of antenna ports in the first direction (e.g., horizontal direction), the number of antenna ports in the second direction (e.g., vertical direction), and the number of polarizations (e.g., P = 2), respectively. The index assigned to the CSI-RS antenna port (i.e., Figure 7 The first CSI is derived from the indexes 0 to 15 shown in . The 2D codebook may be a codebook consisting of the Kronecker product of two matrices. The two matrices may be matrices consisting of codewords corresponding to the first direction and the second direction, and the size and elements of each matrix may be determined based on N1 and N2.

[0148] refer to Figure 7 , the second CSI-RS antenna port set may include L2=4 CSI-RS antenna ports mapped to the 8 TXRUs in the first column. The second CSI-RS antenna port set may be determined based on the above-mentioned first configuration information. For example, the first configuration information may be information about the CSI-RS antenna port muting pattern. In the present disclosure, the CSI-RS antenna port muting pattern may be used as a term referring to a set of muted (or unmuted) CSI-RS antenna ports or information indicating the set. In this exemplary embodiment, the first configuration information may indicate 12 CSI-RS antenna ports mapped to the TXRUs in the three columns on the right (i.e., the second column, the third column, and the fourth column). Based on the CSI-RS antenna port muting pattern, the terminal may configure the second CSI-RS antenna port set with the remaining four CSI-RS antenna ports that do not belong to the CSI-RS antenna port muting pattern. For another example, the first configuration information may be information about a CSI-RS antenna port set (or subset). The first configuration information may include the unmuted CSI-RS antenna ports constituting the CSI-RS antenna port set, or information indicating them. In this exemplary embodiment, the first configuration information may indicate four CSI-RS antenna ports of the TXRU mapped to a left column (i.e., the first column). The four CSI-RS antenna ports may be CSI-RS antenna ports 0, 1, 8, and 9.

[0149] The terminal may receive four CSI-RS antenna ports and derive the second CSI based on the CSI codebook corresponding to the four received CSI-RS antenna ports. The CSI codebook may be a 2D codebook of size (N1, N2) = (1, 2) or (N1, N2, P) = (1, 2, 2). Compared to the codebook applied to the first CSI, the size of the codebook is reduced to 1 in the first direction (e.g., horizontal direction) by muting.

[0150] If the CSI-RS antenna port set configured by the above method is smaller in size than the CSI-RS antenna ports constituting the CSI-RS resource, the CSI-RS antenna port index can be reallocated for the CSI-RS antenna port set. For example, the above numbering rule (i.e., second direction → first direction → polarization direction) can be equally applied to the CSI-RS antenna ports constituting the CSI-RS antenna port set. In this exemplary embodiment, the indices of the CSI-RS antenna ports 0, 1, 8, and 9 included in the second CSI-RS antenna port set can be changed to 0, 1, 2, and 3 according to the above rule. Based on the changed (or reallocated) index, the terminal can derive the corresponding CSI, i.e., the second CSI. Even if the index of the CSI-RS antenna port is reallocated, the position of the resource to which the CSI-RS antenna port is mapped may not change. That is, mapping or demapping of the CSI-RS antenna port can be performed based on the index before the change (e.g., based on the index allocated by all CSI-RS antenna ports constituting the CSI-RS resource). Even if CSI-RS antenna ports 8 and 9 are reallocated to indexes 2 and 3, they can still be located at the positions originally occupied by CSI-RS antenna ports 8 and 9 among the 16 CSI-RS antenna ports (i.e., Figure 3 4 REs corresponding to CDM group 2 are sent.

[0151] In (method 100), the above-mentioned silence may be virtual silence. That is, the muted CSI-RS antenna port may be excluded only from the corresponding CSI-RS antenna port set and / or CSI, and may actually be sent from the base station to the terminal. In this embodiment, from the perspective of the first CSI-RS resource set, the 12 CSI-RS antenna ports that are muted for configuring the second CSI-RS resource set may be non-muted CSI-RS, and thus the 12 CSI-RSRS antenna ports may be sent to the terminal. However, for a specific CSI-RS resource, if the muted CSI-RS antenna port is a CSI-RS that is muted for all CSI-RS antenna port sets configured for the terminal, the terminal may not receive the CSI-RS antenna port.

[0152] For one CSI-RS resource, one or more CSI-RS antenna port sets can be configured. Multiple CSI-RS antenna port sets can be distinguished by different indexes. The configuration information of the CSI-RS resource may include first configuration information corresponding to each CSI-RS antenna port set. Like the first CSI-RS resource set in the above exemplary embodiment, a specific CSI-RS antenna port set may be composed of all CSI-RS antenna ports constituting the CSI-RS resource. That is, the specific CSI-RS antenna port set may be the entire set. In this case, the corresponding silent pattern may not include the CSI-RS antenna port. That is, the corresponding silent pattern may be composed of 0 CSI-RS antenna ports. The index of the specific CSI-RS antenna port set may be predefined in the technical specification. For example, the index may be 0.

[0153] The CSI-RS antenna port set can be determined based on the structure (or size) of the associated CSI codebook. For example, when CSI is derived through the above-mentioned 2D codebook, the CSI-RS antenna port set can be determined based on information about the antenna ports constituting the first direction (e.g., horizontal direction) and / or information about the antenna ports constituting the second direction (e.g., vertical direction). That is, the above-mentioned information can be included in the first configuration information. The information about the antenna ports constituting the first direction can be information related to N1, which is the size of the codebook in the first direction, and the information about the antenna ports constituting the second direction can be information related to N2, which is the size of the codebook in the second direction. Additionally or optionally, the first configuration information can be determined based on information about the antenna ports constituting the third direction (or polarization direction), and the information can be information related to P, which is the size of the codebook in the third direction. In an exemplary embodiment, P can be 2. Optionally, P can be a natural number greater than 2. The above-mentioned method can be referred to as (method 110).

[0154] Figure 8 is a conceptual diagram illustrating a second exemplary embodiment of a method for configuring multiple CSI-RS antenna port sets.

[0155] refer to Figure 8 , the terminal can be configured by the base station to receive CSI-RS resources including 16 CSI-RS antenna ports. In this exemplary embodiment, the mapping operation between CSI-RS antenna ports, TXRUs and physical antenna elements can follow Figure 4The operations described in the first exemplary embodiment of . That is, the CSI-RS antenna ports can be arranged in a first direction (e.g., vertical direction), a second direction (e.g., horizontal direction), and a polarization direction. Additionally, the terminal can be configured with a CSI-RS antenna port set (i.e., a subset) consisting of some or all of the 16 CSI-RS antenna ports for CSI reporting on scaled CSI-RS resources. The first CSI-RS antenna port set may include all 16 CSI-RS antenna ports. On the other hand, each of the second to sixth CSI-RS antenna port sets may be configured as part of the 16 CSI-RS antenna ports. The remaining CSI-RS antenna ports not included in the CSI-RS antenna port set may be regarded as silent. The terminal may calculate CSI for the CSI-RS antenna port set and report the calculated CSI to the base station. The CSI may be calculated based on a 2D codebook.

[0156] When the CSI-RS antenna ports constituting the first direction (e.g., horizontal direction) and the second direction (e.g., vertical direction) are represented as a 2D matrix, the positions of the CSI-RS antenna ports in each direction can be represented as column indices and row indices. In the above exemplary embodiment, the second CSI-RS antenna port set may consist of 8 CSI-RS antenna ports corresponding to row 1 and all columns, and the fourth CSI-RS antenna port set may consist of 8 CSI-RS antenna ports corresponding to all rows and columns 3 and 4.

[0157] According to (method 110), a CSI-RS antenna port set may be indicated. The first configuration information may include information indicating columns corresponding to CSI-RS antenna ports constituting the first direction and / or information indicating rows corresponding to CSI-RS antenna ports constituting the second direction. Optionally, the first configuration information may include information indicating columns corresponding to CSI-RS antenna ports muted in the first direction and / or information indicating rows corresponding to CSI-RS antenna ports muted in the second direction.

[0158] As a specific method, the information can be expressed as a set of row indices and / or a set of column indices. According to the above method, the configuration information of the first CSI-RS antenna port set may include a row index set {0, 1} and a column index set {0, 1, 2, 3}, the configuration information of the second CSI-RS antenna port set may include a row index set {0} and a column index set {0, 1, 2, 3}, and the configuration information of the fourth CSI-RS antenna port set may include a row index set {0, 1} and a column index set {2, 3}. Optionally, the configuration information of the first CSI-RS antenna port set may include an index set Φ of silent rows and an index set Φ of silent columns, the configuration information of the second CSI-RS antenna port set may include an index set Φ of silent rows and an index set Φ of silent columns, and the configuration information of the fourth CSI-RS antenna port set may include an index set Φ of silent rows and an index set Φ of silent columns. Here, Φ may represent an empty set.

[0159] As another method, the information can be expressed as (index of the starting row, index of the ending row) and / or (index of the starting column, index of the ending column). According to the above method, the configuration information of the first CSI-RS antenna port set may include '(starting row, ending row) = (0, 1)' and '(starting column, ending column) = (0, 3)', the configuration information of the second CSI-RS antenna port set may include '(starting row, ending row) = (0, 0) and (starting column, ending column) = (0, 3)', and the configuration information of the fourth CSI-RS antenna port set may include '(starting row, ending row) = (0, 1) and (starting column, ending column) = (2, 3)'. Optionally, the configuration information of the first CSI-RS antenna port set may include information indicating that there is no silent row (e.g., '(starting row, ending row) = (0, 0)') and information indicating that there is no silent column (e.g., '(starting column, ending column) = (0, 0)'), the configuration information of the second CSI-RS antenna port set may include information indicating a silent row (e.g., '(starting row, ending row) = (1, 1)') and information indicating that there is no silent column (e.g., '(starting column, ending column) = (0, 0)'), and the configuration information of the fourth CSI-RS antenna port set may include information indicating that there is no silent row (e.g., '(starting row, ending row) = (0, 0)') and information indicating a silent column (e.g., '(starting column, ending column) = (0, 1)').

[0160] As another method, the information can be expressed as (index of the starting row, the number of consecutive rows) and / or (index of the starting column, the number of consecutive columns). According to the above method, the configuration information of the first CSI-RS antenna port set may include '(starting row, number of rows) = (0, 2)' and '(starting column, number of columns) = (0, 4)', the configuration information of the second CSI-RS antenna port set may include '(starting row, number of rows) = (0, 1)' and '(starting column, number of columns) = (0, 4)', and the configuration information of the fourth CSI-RS antenna port set may include '(starting row, number of rows) = (0, 2)' and '(starting column, number of columns) = (2, 2)'. Optionally, the configuration information of the first CSI-RS antenna port set may include information indicating that there is no silent row (for example, '(starting row, number of rows) = (0, 0) or (A, 0)', A is an arbitrarily configurable value) and information indicating that there is no silent column (for example, '(starting column, number of columns) = (0, 0) or (A, 0)'), the configuration information of the second CSI-RS antenna port set may include information indicating a silent row (for example, '(starting row, number of rows) = (1, 1)') and information indicating that there is no silent column (for example, '(starting column, number of columns) = (0, 0) or (A, 0)'), and the configuration information of the fourth CSI-RS antenna port set may include information indicating that there is no silent row (for example, '(starting row, number of rows) = (0, 0) or (A, 0)') and information indicating a silent column (for example, '(starting column, number of columns) = (0, 2)').

[0161] According to the above method, all consecutive CSI-RS antenna ports in each domain can be indicated by the first configuration information. That is, the first to sixth CSI-RS antenna port sets can be indicated by the first configuration information. In addition, there can be CSI-RS antenna port sets that provide the same CSI measurement effect within one CSI-RS resource. In the above exemplary embodiment, the third CSI-RS antenna port set and the fourth CSI-RS antenna port set can provide the same effect, and the fifth CSI-RS antenna port set and the sixth CSI-RS antenna port set can provide the same effect. In this case, allowing the third CSI-RS antenna port set and the fourth CSI-RS antenna port set to be configured at the same time, or allowing the fifth CSI-RS antenna port set and the sixth CSI-RS antenna port set to be configured at the same time, may result in unnecessary redundancy, and the signaling overhead of the first configuration information may increase.

[0162] As a method for solving the above problem, a method of fixing the position of the starting CSI-RS antenna port in each transmission direction can be applied. For example, the position of the CSI-RS antenna ports constituting each CSI-RS antenna port set can start from the first row 1 (i.e., the row with index 0) in the second direction (e.g., the vertical direction), and can start from the first column (i.e., the column with index 0) in the first direction (e.g., the horizontal direction). In addition, each CSI-RS antenna port set can include at least the CSI-RS antenna ports corresponding to the first row and the first column. A CSI-RS antenna port set consisting of CSI-RS antenna ports that meet the above conditions can be configured in the terminal. In the above exemplary embodiment, the first, second, third, and fifth CSI-RS antenna port sets can meet the above conditions and can be configured in the terminal for CSI measurement and reporting. However, since each of the fourth CSI-RS antenna port set and the sixth CSI-RS antenna port set does not include the CSI-RS antenna ports in the first row and the first column, they may not meet the above conditions and can be considered as invalid configurations.

[0163] According to the above method, the first configuration information may be represented as an index of an end row and / or an index of an end column. That is, the first configuration information may not include an index of a start row or an index of a start column. According to the above method, the configuration information of the first CSI-RS antenna port set may include "(end row) = (1) and (end column) = (3)", and the configuration information of the second CSI-RS antenna port set may include "(end row) = (0) and (end column) = (3)". Optionally, the configuration information of the first CSI-RS antenna port set may include information indicating that there is no silent row (e.g., "(end row) = (0)") and information indicating that there is no silent column (e.g., "(end column) = (0)"), and the configuration information of the second CSI-RS antenna port set may include information indicating a silent row (e.g., "(end row) = (1)") and information indicating that there is no silent column (e.g., "(end column) = (0)"). On the other hand, the fourth CSI-RS antenna port set and the sixth CSI-RS antenna port set may be considered to be invalid configurations.

[0164] As another method, the first configuration information may be expressed as the number of consecutive rows and / or the number of consecutive columns. That is, the first configuration information may not include the index of the starting row or the index of the starting column. According to the above method, the configuration information of the first CSI-RS antenna port set may include "(number of rows) = (2) and (number of columns) = (4)", and the configuration information of the second CSI-RS antenna port set may include "(number of rows) = (1) and (number of columns) = (4)". Optionally, the configuration information of the first CSI-RS antenna port set may include information indicating that there are no silent rows (e.g., '(number of rows) = (0)') and information indicating that there are no silent columns (e.g., '(number of columns) = (0)'), and the configuration information of the second CSI-RS antenna port set may include information indicating that there are no silent rows (e.g., '(number of rows) = (1)') and information indicating that there are no silent columns (e.g., '(number of columns) = (0)'). On the other hand, the fourth CSI-RS antenna port set and the sixth CSI-RS antenna port set may be considered as invalid configurations.

[0165] In the above method, the number of rows and the number of columns may correspond to N2 and N1, respectively, where N2 and N1 are configuration information indicating the size of the 2D codebook. In other words, the first configuration information may include N1 and N2, where N1 and N2 are configuration information indicating the size of the 2D codebook. For example, the configuration information of the first CSI-RS antenna port set may include (N1, N2) = (4, 2) or (N1, N2, P) = (4, 2, 2), and the configuration information of the second CSI-RS antenna port set may include (N1, N2) = (1, 2) or (N1, N2, P) = (1, 2, 2). Optionally, the configuration information of the first CSI-RS antenna port set may include information indicating that there are no silent rows and no silent columns (e.g., (N1, N2) = (0, 0) or (N1, N2, P) = (0, 0, 2)), and the configuration information of the second CSI-RS antenna port set may include information indicating the number of silent rows (e.g., N2 = 2) and information indicating that there are no silent columns (e.g., N1 = 0 or (N1, N2, P) = (0, 2, 2)). Similarly, the fourth CSI-RS antenna port set and the sixth CSI-RS antenna port set may be considered invalid configurations.

[0166] According to the above method, the first configuration information may include configuration information of a codebook (e.g., a 2D codebook) associated with a CSI-RS antenna port set. Alternatively, the first configuration information may be replaced with codebook configuration information or may be considered as codebook configuration information. Additionally, the first configuration information may be sent to the terminal when included in CSI report configuration information rather than CSI-RS resource configuration information. For example, the first configuration information may be included in CSI report configuration information or CSI report sub-configuration information associated with a CSI-RS antenna port set. In this case, the first configuration information may be represented in the form of codebook configuration information. The terminal may know (or identify) the CSI-RS antenna ports constituting the CSI-RS antenna port set based on the codebook configuration information (e.g., N1 and N2) included in the CSI report configuration or CSI report sub-configuration. In this case, the CSI-RS resource configuration may not additionally include the first configuration information for the CSI-RS antenna port set. Alternatively, the CSI-RS resource configuration may include second configuration information in addition to the first configuration information (e.g., codebook configuration information, N1, and N2) included in the CSI report configuration. For example, the second configuration information may include information about the number of CSI-RS antenna ports that constitute the CSI-RS antenna port set. The terminal may use only the first configuration information included in the CSI report configuration to identify the CSI-RS antenna port subset, or may use both the first configuration information included in the CSI report configuration and the second configuration information included in the CSI-RS resource configuration to identify the CSI-RS antenna port subset. As another example, both the first configuration information and the second configuration information may be included in the CSI report configuration information. Alternatively, both the first configuration information and the second configuration information may be included in the CSI-RS resource configuration information.

[0167] According to an exemplary embodiment, the first CSI report configuration may be associated with the first CSI-RS resource. Optionally, the first CSI report configuration may reference the first CSI-RS resource. The first CSI-RS resource may consist of C CSI-RS antenna ports and may be mapped to D REs based on a CSI-RS resource mapping rule configured in the terminal. For example, D may be equal to C. The first CSI report configuration may include codebook configuration information corresponding to the C CSI-RS antenna ports constituting the first CSI-RS resource. The codebook configuration information may include information about the size (N1, N2) of the codebook. Here, N1 and N2 may be natural numbers satisfying 2*N1*N2=C. For convenience, the codebook corresponding to the CSI report configuration may be referred to as a parent codebook.

[0168] The first CSI report configuration may be associated with multiple (e.g., A) CSI report subconfigurations. The ath CSI report subconfiguration may include information about C(a) CSI-RS antenna ports and codebook configuration information corresponding to the C(a) CSI-RS antenna ports (where 1≤a≤A), where the C(a) CSI-RS antenna ports are a subset of the C CSI-RS antenna ports constituting the first CSI-RS resource. The codebook configuration information may include information about the size of the codebook (N1(a), N2(a)). Here, N1(a) and N2(a) may be natural numbers that satisfy 2*N1(a)*N2(a)=C(a). For convenience, the codebook corresponding to each CSI report subconfiguration may be referred to as a subcodebook.

[0169] There can be an association between the parent codebook and each child codebook. Based on the above concept, an inclusion relationship can be established between the CSI-RS resources (i.e., the antenna ports that constitute the CSI-RS resources) and the CSI-RS antenna port set (i.e., a subset of the antenna ports). Based on this, the size of each dimension of the child codebook can be determined to a value that does not exceed the size of each dimension of the parent codebook. In other words, for a given a, the relationship N1(a) ≤ N1 and N2(a) ≤ N2 can be established.

[0170] The codebook configuration information may also include other information in addition to N1 and N2. For example, the codebook configuration information may include the number of panels to which the CSI-RS antenna ports are mapped. The terminal may use only some codewords in the codebook to derive CSI. Codebook subset restriction information indicating the set of codewords to be used or not used by the terminal for CSI reporting may be included in the codebook configuration information.

[0171] The above method can be applied to a type 1 CSI codebook. A type 1 CSI codebook may include a single-panel codebook and a multi-panel codebook. In the case of a single-panel codebook, the size of the codebook may be given by N1 and N2. In the case of a multi-panel codebook, the size of the codebook may be given by N1, N2, and the number of panels (or the number of coherent groups configured by the antenna panels) (e.g., Ng). In the case of a multi-panel codebook, if the number of polarizations P is additionally considered as described above, the size of the codebook may be given by N1, N2, the number of panels (or coherent groups), and the number of polarizations P. In addition, the above method may also be applied to a type 2 CSI codebook. When the codeword constituting each dimension is generated based on a discrete Fourier transform (DFT) matrix or a DFT vector, oversampling may be applied to a type 1 CSI codebook and a type 2 CSI codebook. (O1, O2) as a combination of oversampling factors may be determined based on (N1, N2) and / or the number of CSI-RS antenna ports. Optionally, (O1, O2) as a combination of oversampling factors can be determined based on (N1, N2, Ng) and / or the number of CSI-RS antenna ports. That is, the terminal can determine (O1, O2) to be applied to the codebook based on a predefined rule without relying on signaling from the base station. In the above exemplary embodiment, (O1, O2) can be the oversampling factor of the parent codebook. The oversampling factor of the subcodebook corresponding to the a-th CSI report subconfiguration can be referred to as (O1(a), O2(a)). Unlike the case of the parent codebook, (O1(a), O2(a) to be applied to each subcodebook can be signaled from the base station to the terminal. For example, information about (O1(a), O2(a)) can be included in the configuration information of the a-th CSI report subconfiguration. Optionally, (O1(a), O2(a)) to be applied to each subcodebook may be determined based on (N1(a), N2(a)) and / or the number of CSI-RS antenna ports C(a).

[0172] Additionally or optionally, the CSI-RS antenna port set corresponding to each CSI report configuration may be represented as a bitmap. The length of the bitmap may be C. Each of the C bits constituting the bitmap may indicate whether each CSI-RS antenna port constituting the CSI-RS resource is muted. For example, a CSI-RS antenna port corresponding to a bit with a value of "1" (or "0") may be considered to be included in the CSI-RS antenna port set, and a CSI-RS antenna port corresponding to a bit with a value of "0" (or "1") may be considered to be excluded from the CSI-RS antenna port set. In the bitmap corresponding to the a-th CSI report subconfiguration, the values ​​of the bits corresponding to C(a) CSI-RS antenna ports may be set to "1" (or "0"). That is, the number of bits whose values ​​are set to '1' may be C(a). C(a) may match the value 2*N1(a)*N2(a). The bitmap or information about the bitmap may be included in the configuration information of each CSI report subconfiguration and may be sent to the terminal.

[0173] According to an exemplary embodiment, each bit in the bitmap can be determined independently, regardless of the values ​​of other bits. That is, the bitmap can be configured as a bit string, and the spatial element pattern can be configured with antenna ports in the CSI-RS antenna ports constituting the CSI-RS resource. For example, the CSI-RS antenna port subset indicated by the bitmap can be mapped to a single-polarized antenna. As another example, the CSI-RS antenna port subset indicated by the bitmap can have a non-uniform pattern in the horizontal domain and / or the vertical domain. In addition, in a communication system (e.g., an NR communication system), the CSI codebook can be designed to have optimal performance in a uniform two-dimensional planar array antenna structure with cross-polarization. In this case, when the spatial element pattern is configured as in the above exemplary embodiment, the CSI accuracy may be reduced.

[0174] According to another exemplary embodiment, multiple bits mapped to a specific position in the bitmap may have the same value. For example, two CSI-RS antenna ports mapped to a set of two antenna elements with the same position and different polarizations may be silenced together or transmitted together (i.e., not silent). The bits corresponding to the two CSI-RS antenna ports may have the same value (e.g., all 1s, all 0s). Specifically, when the length of the bitmap is P, the i-th bit and the (i+P / 2)-th bit of the bitmap may correspond to two CSI-RS antenna ports with the same spatial position and different polarizations, and the bits may have the same value. That is, the bit string of the first (P / 2) bits of the bitmap and the bit string of the last (P / 2) bits of the bitmap may be the same.

[0175] In addition, the CSI-RS antenna ports constituting the CSI-RS resources may be mapped to multiple panels. In this case, except for the cross-polarization structure, the patterns (e.g., quantity and mapping structure) of the CSI-RS antenna ports mapped to the multiple panels may be the same. For example, if the number of panels is 2 (Ng=2), the first (P / 2) bits of the bitmap may correspond to the CSI-RS antenna ports mapped to the first panel, and the last (P / 2) bits of the bitmap may correspond to the CSI-RS antenna ports mapped to the second panel. In this case, the bit string of the first (P / 2) bits and the bit string of the last (P / 2) bits may be the same. Additionally, the first (P / 4) bits of the bitmap may correspond to the CSI-RS antenna port corresponding to the first polarization of the first panel, the second (P / 4) bits of the bitmap may correspond to the CSI-RS antenna port corresponding to the second polarization of the first panel, the third (P / 4) bits of the bitmap may correspond to the CSI-RS antenna port corresponding to the first polarization of the second panel, and the last (P / 4) bits of the bitmap may correspond to the CSI-RS antenna port corresponding to the second polarization of the second panel. In this case, the bit string of the first (P / 4) bits and the bit string of the second (P / 4) bits may be the same. Additionally, the bit string of the third (P / 4) bits and the bit string of the last (P / 4) bits may be the same. That is, all four bit strings may match. The base station may determine the bitmap by considering the above constraints and may configure the CSI-RS antenna port subset for the CSI report subconfiguration by signaling the determined bitmap to the terminal. The terminal may desire to be configured with a bitmap that satisfies the above conditions. If the bitmap does not meet the above conditions, the terminal can ignore the configuration and omit the CSI reporting process corresponding to the configuration (for example, the CSI report for the corresponding CSI reporting subconfiguration, or all CSI reports belonging to the corresponding CSI reporting subconfiguration).

[0176] A specific spatial element pattern (e.g., a specific CSI report subconfiguration) may consist of two CSI-RS antenna ports. For example, the base station may indicate to the terminal that the size of the codebook corresponding to the CSI report subconfiguration is (N1, N2) = (1, 1) or (N1(a), N2(a)) = (1, 1). The configuration information of the CSI report subconfiguration may include codebook configuration information. As another example, the configuration information of the CSI report subconfiguration may explicitly indicate that the number of CSI-RS antenna ports in the corresponding CSI-RS antenna port set is 2. The terminal may derive CSI based on the two corresponding CSI-RS antenna ports. The two CSI-RS antenna ports may be antenna ports corresponding to a specific row (e.g., the first row) and a specific column (e.g., the first column) in the spatial mapping structure of the CSI-RS antenna ports. In this case, the CSI may be calculated based on a separate codebook (i.e., a codebook to be used when the number of CSI-RS antenna ports is 2 as defined in the technical specification). The codebook may be a codebook that is not configured as a Kronecker product of two matrices. Optionally, in the above method, a spatial element pattern consisting of two CSI-RS antenna ports (eg, a CSI reporting sub-configuration) may be excluded. A terminal may not desire a configuration like the above example.

[0177] An inclusion relationship can be established between the CSI-RS antenna port sets configured in the terminal. In the above exemplary embodiment, an inclusion relationship is established between any two CSI-RS antenna port sets in the first, second and fifth CSI-RS antenna port sets, and CSI-RS antenna port sets for the same CSI-RS resources can be configured in the terminal at the same time. On the other hand, an inclusion relationship may not be established between the second and third CSI-RS antenna port sets, and the CSI-RS antenna port sets for which an inclusion relationship is not established may not be configured to be associated with the same CSI-RS resources. Similarly, an inclusion relationship can be established between the CSI-RS muting patterns configured in the terminal (i.e., muted CSI-RS antenna port sets), and the terminal can be simultaneously configured with CSI-RS muting patterns for which an inclusion relationship is established for the same CSI-RS resources. CSI-RS muting patterns for which an inclusion relationship is not established may not be configured to be associated with the same CSI-RS resources.

[0178] In addition, an inclusion relationship can be established between codebooks associated with CSI-RS antenna port sets within the same CSI-RS resource or between codebooks associated with the same CSI-RS resource. In the above exemplary embodiments, the CSI corresponding to the first CSI-RS antenna port set can be derived based on a 2D codebook having a structure of (N1, N2) = (4, 2) or (N1, N2, P) = (4, 2, 2), and the CSI corresponding to the second CSI-RS antenna port set can be derived based on a 2D codebook having a structure of (N1, N2) = (4, 1) or (N1, N2, P) = (4, 1, 2). The latter 2D codebook can be configured as a part of the previous 2D codebook and can have a length less than or equal to (or not greater than) the previous 2D codebook in each transmission direction (or domain). The lengths (denoted as P) of the polarization directions (or domains) of the codebooks associated with the CSI-RS antenna port sets can be the same. In the above exemplary embodiment, both the previous 2D codebook and the next 2D codebook may have P=2.

[0179] Within each CSI-RS antenna port set, the CSI-RS antenna port numbers may be numbered in ascending order starting from 0 (or starting from 3000 in the NR communication system). In the above exemplary embodiment, with respect to the entire CSI-RS resource before muting is applied, the eight CSI-RS antenna ports constituting the third CSI-RS antenna port set may have antenna port numbers 0, 1, 2, 3, 8, 9, 10, and 11. However, they may be renumbered from 0 to 7 within the CSI-RS antenna port set. The terminal may calculate CSI (e.g., PMI, CQI, RI) based on the numbers indexed within the CSI-RS antenna port set.

[0180] Configuration information about the CSI codebook applied to the CSI calculation may be included in the CSI report configuration information and may be associated with each CSI report. In the case of the second CSI reporting method, the CSI codebook configuration information may be included in each CSI report sub-configuration information and may be used for the CSI report corresponding to each CSI report sub-configuration. When the terminal performs the above-mentioned CSI-RS reception and CSI measurement operations based on the CSI-RS resource, the above-mentioned CSI-RS reception and CSI measurement operations may be performed based on the codebook configuration information included in the CSI report associated with the CSI-RS resource. Optionally, information about the CSI codebook may be included in the CSI resource configuration information and may be associated with each CSI resource or each CSI-RS resource. The configuration information of the 2D codebook may include at least N1 and / or N2. The configuration information of the 2D codebook may additionally include P. In Figure 8In the first exemplary embodiment, (N1, N2) = (4, 2) or (N1, N2, P) = (4, 2, 2), and based on this information, the terminal can assume the arrangement of the CSI-RS antenna ports shown in the drawing.

[0181] According to (method 100), the base station can send all CSI-RS antenna ports constituting the CSI-RS resource in each period to the terminal. Alternatively, the base station can send the union of all CSI-RS antenna port sets configured in the CSI-RS resource in each period to the terminal. That is, before the CSI-RS resource is reconfigured, the terminal can receive the same number of CSI-RS antenna ports in the CSI-RS resource in each period (e.g., each CSI-RS opportunity).

[0182] In addition, among the CSI-RS antenna port sets configured in the terminal, some CSI-RS antenna port sets can be dynamically indicated to the terminal. Dynamic indication can be performed through DCI. The DCI may include information about the ID or index of the CSI-RS antenna port set to be indicated to the terminal. Additionally or optionally, as described above, some of the CSI reporting configurations or CSI reporting subconfigurations configured in the terminal can be dynamically indicated to the terminal. The DCI may include information about the ID or index of the CSI reporting configuration or CSI reporting subconfiguration to be indicated to the terminal, and may indicate the corresponding CSI reporting operation. The terminal may perform CSI measurement and reporting operations for the indicated CSI-RS antenna port set and / or the indicated CSI reporting configuration (or CSI reporting subconfiguration). The terminal may not perform CSI measurement and reporting operations for CSI-RS antenna port sets and / or CSI reporting configurations (or CSI reporting subconfigurations) that are not indicated.

[0183] As another method, the terminal can send CSI reports for all configured CSI-RS antenna port sets and all configured CSI report configurations (or all CSI report subconfigurations) to the base station, regardless of whether the CSI-RS antenna port sets and / or CSI report configurations (or CSI report subconfigurations) are dynamically indicated. In this case, the CSI reports corresponding to the unindicated CSI-RS antenna port sets and / or unindicated CSI report configurations (or CSI report subconfigurations) can have dummy values. According to this solution, the size of the CSI report information can remain constant regardless of the dynamic indication.

[0184] Figure 9 is a conceptual diagram illustrating a second exemplary embodiment of a CSI reporting method based on multiple CSI-RS antenna port sets.

[0185] refer to Figure 9, the terminal can receive the configuration information of CSI-RS resources from the base station. t = 16 CSI-RS antenna ports. CSI-RS resources may appear periodically and repeatedly.

[0186] The terminal may be configured or instructed by the base station to have a CSI-RS antenna port to be received in the CSI-RS resource, that is, a set (that is, a subset) of CSI-RS antenna ports. In the above exemplary embodiment, the terminal may receive the first DCI and may be instructed to receive (that is, activate) the CSI-RS resource configured with L1=L based on the first DCI. t =16 CSI-RS antenna ports. The terminal may measure CSI based on the first CSI-RS antenna port set during a first time period for receiving the first CSI-RS antenna port set, and report the first CSI corresponding to the first CSI-RS antenna port set to the base station. In addition, the terminal may receive a second DCI, and may be instructed to receive a second CSI-RS antenna port set configured with L2=4 CSI-RS antenna ports in the CSI-RS resource based on the second DCI. The terminal may measure CSI based on the second CSI-RS antenna port set during a second time period for receiving the second CSI-RS antenna port set, and report the second CSI corresponding to the second CSI-RS antenna port set to the base station. The above method may be referred to as (method 200).

[0187] As a specific method of indicating a CSI-RS antenna port set, the terminal can configure multiple CSI-RS antenna port sets based on the configuration information received from the base station. The configuration information can be sent based on higher layer signaling (e.g., RRC signaling, MAC CE). The terminal can be instructed by DCI to use one (or more than one) CSI-RS antenna port set from multiple CSI-RS antenna port sets. The DCI may include an ID or index of the CSI-RS antenna port set to be indicated. Optionally, the configuration information of the CSI-RS antenna port set can be directly included in the DCI, and the terminal can configure the CSI-RS antenna port set based on the DCI and receive the CSI-RS antenna port set. Optionally, the CSI-RS antenna port set can be indicated only by higher layer signaling (e.g., RRC signaling, MAC CE) without the need for a DCI transmission process.

[0188] As another method, as described above, the terminal may receive a CSI report configuration including multiple CSI report subconfigurations from the base station. Each CSI report subconfiguration may correspond to each spatial element pattern, that is, each CSI-RS antenna port set. The terminal may be instructed by DCI to receive one (or more than one) CSI report subconfiguration, receive the CSI-RS antenna port set corresponding to the CSI report subconfiguration, and perform CSI measurement and reporting operations corresponding to the above method. The terminal may omit the operation of receiving the CSI-RS antenna ports that are not included in the indicated CSI-RS antenna port set among the CSI-RS antenna ports belonging to the CSI-RS resource or CSI-RS resource set.

[0189] If there are multiple CSI report subconfigurations indicated, the above-mentioned codebook inclusion relationship can be established for multiple CSI report subconfigurations. For example, the configuration information of the first codebook of the first CSI report subconfiguration and the second codebook of the second CSI report subconfiguration indicated by the DCI can include (N1(1), N2(1)) and (N1(2) and N2(2)), respectively. In this case, the horizontal domain codeword length and the vertical domain codeword length of the first codebook can be less than or equal to the horizontal domain codeword length and the vertical domain codeword length of the second codebook, respectively. That is, N1(1)≤N1(2) and N2(1)≤N2(2).

[0190] In order to substantially improve the power efficiency of the base station, the above-mentioned CSI-RS antenna port scaling or silencing method can be commonly applied to multiple terminals communicating with the base station. Therefore, information indicating the CSI-RS antenna port set and / or configuration information of the CSI-RS antenna port set can be sent to the terminal (or terminal group) based on the group-common DCI. In the NR communication system, the group-common DCI can have a DCI format 2_X (X is an integer greater than or equal to 0). The terminal can monitor the group-common DCI in a CSS set (e.g., a type 3 CSS set). The CSS set can be associated with a CORESET. When DRX operation is configured in the terminal, the group-common DCI can be monitored during the DRX active time (or on duration). In addition, the group-common DCI may also include information indicating the DRX operation of the terminal (or cell DTX operation, DRX operation of the terminal corresponding to the cell DTX operation). For example, the group-common DCI may additionally include information instructing the terminal to wake up at the next active time (or on-duration) and perform a PDCCH monitoring operation, a downlink signal reception operation, etc., information instructing the terminal to enter a sleep mode at the next inactive time and skip receiving (at least some) downlink signals, etc. For the wake-up indication, the terminal may monitor the group-common DCI (or the corresponding search space set CORESET) in a period outside the DTX active time (or in the inactive time).

[0191] Similarly, as in the above method, the CSI reporting subconfiguration can be indicated by a group-common DCI. Each CSI reporting subconfiguration can correspond to each spatial element pattern, that is, each CSI-RS antenna port set. The group-common DCI can be used to indicate that the terminal receives one (or more than one) CSI reporting subconfiguration, receives the CSI-RS antenna port set corresponding to the CSI reporting subconfiguration, and performs the corresponding CSI measurement and reporting operations using the above method.

[0192] In the CSI-RS resource reception operation and the corresponding CSI measurement and reporting operation, the terminal may apply the CSI-RS antenna port set indicated by the DCI and receive the CSI-RS resources (i.e., the applied CSI-RS antenna port set) from the first time. The first time may be determined based on the time when the DCI is received. For example, the first time may be determined as the time after a specific time offset has passed from the time when the DCI is received. The first time may be indicated as a time slot. The first time may be a time slot after the time slot in which the DCI is received. For example, the first time may be determined as the time slot to which the symbol belongs (the symbol is located A (A is a natural number) symbols after the symbol (e.g., the last symbol) in which the DCI is received), or as the next time slot of the time slot. A may be predefined in the technical specification. A may be determined by the PDCCH reception capability or the capability of the terminal. When activation and deactivation operations are applied to CSI-RS resources or CSI-RS antenna port sets, the CSI-RS antenna port set indicated by the DCI may be considered to be activated from the time when the DCI is received or from the first time. In addition, the CSI-RS antenna port set indicated by the DCI can be considered to be activated by default (ie, without a separate activation indication). While activating the indicated CSI-RS antenna port set, the previous CSI-RS antenna port set can be deactivated.

[0193] If the (activated) CSI-RS antenna port set is changed using the above method, the terminal may reset the CSI measurement operation. The terminal may reset the CSI measurement operation based on a first time (i.e., the time from when the indicated CSI-RS antenna port set is applied). Therefore, the CSI corresponding to the indicated CSI-RS antenna port set may be calculated based on CSI-RS resources (or CSI-RS opportunities) received in the time period from the first time (e.g., the time slot corresponding to the first time) to the CSI reference resource (e.g., the time slot corresponding to the CSI reference resource). CSI-RS resources (or CSI-RS opportunities) received before the first time (e.g., the time slot corresponding to the first time) may not be used to derive the CSI corresponding to the indicated CSI-RS antenna port set. Based on the above reset operation, one CSI (i.e., one CSI instance, one CSI reporting instance) reported to the base station may be calculated based on the CSI-RS resources (or CSI-RS opportunities) received for one CSI-RS antenna port set, while still ensuring CSI accuracy. The CSI reference resource may be determined as a time slot that is sufficiently prior to the CSI reporting time (e.g., time slot) by a reference value. The CSI reference resource may be a downlink time slot. Alternatively, the CSI reference resource may be a time slot that includes at least one downlink symbol or a flexible symbol.

[0194] The operation of configuring the CSI-RS antenna port set by the terminal may be performed by the above method. The first configuration information may be sent to the terminal, and the first configuration information may include information about the CSI-RS antenna ports constituting the CSI-RS antenna port set or information about the silent CSI-RS antenna ports excluded from the CSI-RS antenna port set. In addition, the information may be expressed as information about the position of the CSI-RS antenna port in each dimension of the 2D codebook (e.g., information indicating the position of an element of a matrix) based on (method 110).

[0195] According to (method 200), the number of CSI-RS antenna ports (or CSI-RS antenna port sets) received by the terminal for the same CSI-RS resource can change over time. Additionally, the number of TXRUs used for CSI-RS transmission can change over time. In the above exemplary embodiment, in the first time period in which the first CSI-RS antenna port set is transmitted, 32 TXRUs can be used for CSI-RS transmission. On the other hand, in the second time period in which the second CSI-RS antenna port set is transmitted, 8 TXRUs can be used for CSI-RS transmission. The number of TXRUs used for CSI-RS transmission can match the number of TXRUs used to transmit other signals (e.g., PDSCH) in the same time period. Therefore, the base station can operate only a small number of TXRUs in the second time period including the CSI-RS transmission symbol (i.e., the symbol in which the CSI-RS is transmitted). As a result, compared to (method 100) which requires higher power consumption in the CSI-RS transmission symbol and in the periods before and after the CSI-RS transmission symbol, (method 200) may be advantageous for low-power operation. In addition, according to (method 200), the terminal can measure and send only one CSI report for each CSI reporting instance, and compared with (method 100) of sending multiple CSI reports each time, the computational complexity and uplink resource efficiency of the terminal can be improved.

[0196] Hereinafter, a specific method for mapping a CSI-RS antenna port set to a CSI-RS resource according to an exemplary embodiment of the present disclosure will be described. The exemplary embodiments (methods 310 to 330) described below and their detailed exemplary embodiments can be applied to (method 100) or (method 200) described above.

[0197] Figure 10 is a conceptual diagram illustrating a first exemplary embodiment of a resource mapping method for a CSI-RS antenna port set.

[0198] refer to Figure 10 The first CSI-RS antenna port set and the second CSI-RS antenna port set of the above exemplary embodiment can be mapped to TXRUs (i.e., corresponding physical antenna elements) arranged in a first direction (e.g., horizontal direction), a second direction (e.g., vertical direction), and a third direction (e.g., polarization direction). In addition, the first CSI-RS antenna port set and the second CSI-RS antenna port set can be indicated based on information about a 2D matrix corresponding to the first direction and the second direction (or information about a three-dimensional (3D) matrix corresponding to the first direction, the second direction, and the third direction).

[0199] Each CSI-RS antenna port set may be transmitted while being mapped on a CSI-RS resource. The first CSI-RS antenna port set may consist of all CSI-RS antenna ports constituting the CSI-RS resource, and thus the first CSI-RS antenna port set may follow the RE mapping pattern consisting of all CSI-RS antenna ports indicated by the CSI-RS resource configuration. That is, the 16 CSI-RS antenna ports constituting the first CSI-RS antenna port set may be transmitted in the same manner as Figure 3 . On the other hand, the second CSI-RS antenna port set may consist of some CSI-RS antenna ports constituting CSI-RS resources. In this case, several methods can be considered for mapping the four CSI-RS antenna ports constituting the second CSI-RS antenna port set to CSI-RS resources.

[0200] The first method is Figure 10 In the method shown, the CSI-RS antenna ports constituting the CSI-RS antenna port set can follow the RE mapping pattern defined for all CSI-RS antenna ports indicated by the CSI-RS resource configuration as is. In the above exemplary embodiment, the four CSI-RS antenna ports 0 to 3 may correspond to the numbers 0, 1, 8, and 9 before being newly indexed and may be mapped to 4 REs of CDM group 0, 4 REs of CDM group 0, 4 REs of CDM group 2, and 4 REs of CDM group 2, wherein the CSI-RS antenna ports 0, 1, 8, and 9 are mapped to 4 REs of CDM group 0, 4 REs of CDM group 0, 4 REs of CDM group 2, and 4 REs of CDM group 2, respectively, in the entire mapping pattern consisting of 16 CSI-RS antenna ports before being muted. Different codes (e.g., different OCCs) may be applied to CSI-RS antenna ports belonging to the same CDM group. As a result, the four CSI-RS antenna ports can be mapped to eight REs, and the eight REs can occupy four symbols and two subcarriers. The remaining eight REs (i.e., the four REs in CDM group 1 and the four REs in CDM group 3) to which the four CSI-RS antenna ports are not mapped in the entire mapping pattern can be muted. In other words, the remaining eight REs may not be used for transmitting CSI-RS resources. The above method may be referred to as (Method 310).

[0201] According to (method 310), even if the CSI-RS antenna port set is scaled and the CSI-RS antenna ports are re-indexed, the mapping relationship between the CSI-RS antenna ports and the REs can be maintained. Therefore, the implementation complexity of the terminal can be relatively low. Additionally, a common mapping pattern can be used between terminals that receive CSI-RS antenna port sets to which different scaling is applied, and CSI-RS resources can be shared between terminals. However, in the above exemplary embodiment, in order to transmit the four CSI-RS antenna ports constituting the second CSI-RS antenna port set, 8 REs can be used, which is twice the minimum number of REs required, resulting in a decrease in resource efficiency and an increase in the CSI-RS transmission delay time.

[0202] In the second method, the CSI-RS antenna ports constituting the CSI-RS antenna port set may follow the RE mapping pattern consisting of all CSI-RS antenna ports indicated by the CSI-RS resource configuration, but may be sequentially mapped to CSI-RS antennas based on newly allocated antenna port numbers within the CSI-RS antenna port set. The above method may be referred to as (method 320).

[0203] Figure 11 is a conceptual diagram illustrating a second exemplary embodiment of a resource mapping method for a CSI-RS antenna port set.

[0204] refer to Figure 11 , the CSI-RS antenna port set can be mapped on the CSI-RS resource by (method 320). The four CSI-RS antenna ports constituting the second CSI-RS antenna port set can have newly allocated indexes 0 to 3 within the CSI-RS antenna port set, and they can be mapped according to Figure 1 The same CSI-RS resource mapping rule shown in is mapped to RE based on the index. That is, CSI-RS antenna ports 0 to 3 can be mapped to the 4 REs constituting CDM group 0 according to the rule that they are first mapped in ascending order within the CDM group, and different codes (for example, different OCCs) can be applied thereto. The remaining 12 REs may not be used for the transmission of CSI-RS resources. Compared with the first exemplary embodiment, according to this exemplary embodiment, the second CSI-RS antenna port set can be transmitted by occupying fewer REs and fewer symbols. Accordingly, resource efficiency and transmission delay time can be improved.

[0205] In the third method, the CSI-RS antenna ports constituting the CSI-RS antenna port set can be mapped to the CSI-RS resources according to a separate RE mapping pattern. The separate RE mapping pattern can be determined according to rules predefined in the technical specifications. Alternatively, the separate RE mapping pattern can be sent from the base station to the terminal through a signaling process. The above method may be referred to as (Method 330).

[0206] Figure 12 is a conceptual diagram illustrating a third exemplary embodiment of a resource mapping method for a CSI-RS antenna port set.

[0207] refer to Figure 12 , the CSI-RS antenna port set can be mapped to the CSI-RS resources by (method 330). The four CSI-RS antenna ports constituting the second CSI-RS antenna port set can have newly assigned indices 0 to 3 within the CSI-RS antenna port set and can be mapped to REs by a separate CSI-RS mapping pattern. The separate mapping pattern can consist of two CDM groups, each of the two CDM groups can consist of two adjacent REs in the frequency domain, and the two CDM groups can be mapped to the same symbol. CSI-RS antenna ports 0 to 3 can be first mapped within the CDM group and then mapped in the frequency domain by a rule of indexing in ascending order, so that they are respectively mapped to 2 REs in CDM group 0, 2 REs in CDM group 0, 2 REs in CDM group 1, and 2 REs in CDM group 1. Different codes (e.g., different OCCs) can be applied to CSI-RS antenna ports belonging to the same CDM group. As a result, the four CSI-RS antenna ports can be mapped to 4 REs and 1 symbol. Compared to the first exemplary embodiment, according to this exemplary embodiment, the second CSI-RS antenna port set can be transmitted by occupying fewer REs and fewer symbols. Furthermore, compared to the second exemplary embodiment, according to this exemplary embodiment, the second CSI-RS antenna port set can be transmitted by occupying fewer symbols. Therefore, resource efficiency and transmission delay time can be improved.

[0208] In the above exemplary embodiment, the resources (i.e., a set of REs) constituting a separate RE mapping pattern for a CSI-RS antenna port set may be included in the CSI-RS resources before muting is applied (i.e., a set of REs constituting the CSI-RS resources). Figure 12, the 4 REs to which the second CSI-RS antenna port set is mapped may be a subset of the 16 REs constituting the CSI-RS resource. That is, a nested structure may be established between the CSI-RS resource and the resource to which the CSI-RS antenna port set associated with the CSI-RS resource is mapped. Additionally, a separate RE mapping pattern may be determined based on resource mapping configuration information configured by the base station. For example, at least some of the configuration information regarding the size of the CDM group to be applied to the separate RE mapping pattern, the number of CDM groups, the symbols for arranging each CDM group, the subcarriers for arranging each CDM group, etc. may be signaled from the base station to the terminal. At least some of the above information may be signaled to the terminal separately from the resource mapping configuration information for the CSI-RS resource. For example, the size of the CDM group used for the CSI-RS antenna port set (i.e., 2 in the above example) may be different from the size of the CDM group configured for the CSI-RS resource (i.e., 4 in the above example).

[0209] According to another exemplary embodiment, the resources (i.e., a set of REs) constituting a separate RE mapping pattern for a CSI-RS antenna port set may include other resources (i.e., other REs) in addition to the CSI-RS resources before muting is applied (i.e., the set of REs constituting the CSI-RS resources). For example, the CSI-RS antenna ports constituting the second CSI-RS antenna port set may be mapped to symbols (e.g., third symbols) in addition to the symbols to which the CSI-RS resources are mapped. For another example, the CSI-RS antenna ports constituting the second CSI-RS antenna port set may be mapped to subcarriers (e.g., first subcarriers) in addition to the subcarriers to which the CSI-RS resources are mapped.

[0210] Additionally or alternatively to the above exemplary embodiments, the resources (i.e., a set of REs) constituting a separate RE mapping pattern for a CSI-RS antenna port set may be arranged in the same time resource unit (e.g., the same time slot, the same subframe, the same subslot, etc.) as the time resource unit of the CSI-RS resources (i.e., a set of REs) before muting is applied, and may have the same resource periodicity and time offset. According to the above method, even if the number of CSI-RS antenna ports changes dynamically, the CSI-RS reception periodicity and timing of the terminal can be maintained.

[0211] According to the above exemplary embodiments, due to the CSI-RS muting operation, CSI-RS may not be transmitted in some REs constituting CSI-RS resources. Figure 10 , the CSI-RS antenna port may not be mapped to the 8 REs indicated on the ninth and tenth subcarriers, and the CSI-RS may not be transmitted in the 8 REs. Figure 12, the CSI-RS antenna port may not be mapped to the 12 REs shown in the sixth, ninth, and tenth symbols, and the CSI-RS may not be transmitted in the 12 REs.

[0212] In this case, REs can be used for the transmission of other signals. The terminal can receive downlink signals other than CSI-RS resources in REs. The downlink signals may include PDSCH. That is, the terminal can receive PDSCH in resources including REs to which CSI-RS is not mapped. In other words, PDSCH may not be rate matched with REs to which CSI-RS is not mapped. The terminal can receive PDSCH in resources other than REs to which CSI-RS is actually mapped (i.e., REs to which the activated CSI-RS antenna port set is mapped) among REs constituting CSI-RS resources. That is, PDSCH can be rate matched around REs to which CSI-RS is actually mapped (i.e., REs to which the activated CSI-RS antenna port set is mapped) among REs constituting CSI-RS resources. The above-mentioned rate matching operation may be referred to as a first rate matching operation. Whether to perform the above-mentioned PDSCH rate matching operation can be determined based on the time relationship between the time when the PDSCH is scheduled to the terminal (for example, the time when the terminal receives the scheduling DCI) and the time when the terminal is instructed to receive the CSI-RS antenna port set (for example, the time when the terminal receives the DCI or MAC CE indicating the reception of the CSI-RS antenna port set). If the time when the PDSCH is scheduled to the terminal is not earlier than (or later than) the time when the terminal is instructed to receive the CSI-RS antenna port set, the terminal can receive the PDSCH based on the above-mentioned rate matching operation.

[0213] As another method, even if CSI-RS is not actually transmitted in the RE, the terminal receives PDSCH in resources excluding the RE. That is, PDSCH can be rate matched with all REs constituting the CSI-RS resources. In the above exemplary embodiment, regardless of whether CSI-RS muting is performed, PDSCH can be received in resources excluding the 16 REs constituting the CSI-RS resources. The above rate matching operation can be referred to as a second rate matching operation. The first rate matching operation or the second rate matching operation can be performed selectively. The base station can instruct the terminal to perform one of the first rate matching operation and the second rate matching operation. Such indication information can be sent to the terminal based on a signaling process (e.g., RRC signaling, DCI, MAC CE) from the base station to the terminal. Optionally, the terminal can select one of the first rate matching operation and the second rate matching operation based on predefined rules in the technical specification and perform the selected operation. For example, a predefined rule can be defined based on the time relationship between the time when the PDSCH is scheduled to the terminal (e.g., the time when the terminal receives the scheduling DCI) and the time when the terminal is instructed to receive the CSI-RS antenna port set. If the time when the PDSCH is scheduled is not earlier than (or later than) the time when the terminal is instructed to receive the CSI-RS antenna port set, the terminal may receive the PDSCH based on the first rate matching operation. Otherwise, the terminal may receive the PDSCH based on the second rate matching operation.

[0214] Optionally, the downlink signal may include a PDCCH. The terminal may receive CSI-RS resource configuration information and CORESET configuration information that allows overlap between CSI-RS resources and CORESETs. The terminal may monitor PDCCH candidates belonging to a CORESET (or a corresponding search space set) for PDCCH candidates mapped to resources including REs to which CSI-RS is not mapped, and receive a PDCCH in the corresponding resources.

[0215] Additionally, the terminal may transmit an uplink signal in REs. For example, the REs may be REs in flexible symbols, and the terminal may transmit an uplink signal in resources including REs. To this end, CSI-RS resources and uplink resources may be configured to overlap in the terminal. For example, CSI-RS resources may overlap in the same symbol and / or the same RE as SRS resources. As another example, CSI-RS resources may overlap in the same symbol and / or the same RE as PUCCH resources. The overlap between CSI-RS resources and uplink resources may only be allowed for flexible symbols configured in the terminal.

[0216] In (Method 200), the terminal may receive multiple CSI-RS antenna port sets in a certain CSI-RS resource period (or time period). For example, the base station may instruct the terminal to receive multiple CSI-RS antenna port sets via DCI. The terminal may calculate CSI based on the multiple CSI-RS antenna port sets. For example, the terminal may calculate CSI for each of the multiple CSI-RS antenna port sets. The calculated CSI may be reported to the base station. In other words, (Method 200) may be performed in combination with (Method 100).

[0217] According to the description of the above exemplary embodiments, multiple (or more than one) CSI-RS antenna port sets can be configured or indicated for one CSI-RS resource. The CSI derived based on multiple CSI-RS antenna port sets can be the CSI corresponding to the CSI-RS resource, and can be reported to the base station based on the CSI report configuration corresponding to the CSI-RS resource. However, the above resource configuration is merely an example, and the spirit of the present disclosure is not limited to the above resource configuration, and can be implemented in various forms. For example, in the above exemplary embodiment, "one CSI-RS resource corresponds to one or more CSI-RS antenna port sets" may mean that one CSI-RS resource set corresponds to one or more CSI-RS resources. That is, the CSI-RS resource may correspond to the CSI-RS resource set, and the CSI-RS antenna port set may correspond to the CSI-RS resource. For another example, in the above exemplary embodiment, "one CSI-RS resource corresponds to one or more CSI-RS antenna port sets" may mean that one CSI resource set corresponds to one or more CSI-RS resource sets. That is, a CSI-RS resource may correspond to a CSI resource set, and a CSI-RS antenna port set may correspond to a CSI resource set. In this case, the above-described operations of configuring a CSI-RS antenna port set and associating a CSI-RS antenna port set with a corresponding CSI report may be interpreted as operations of configuring a CSI-RS resource or a CSI-RS resource set and associating it with a corresponding CSI report. For example, first configuration information, a CSI-RS muting pattern, etc. may be configured for each CSI-RS resource or each CSI-RS resource set. The terminal may generate CSI report information for each CSI-RS resource or each CSI-RS resource set and transmit the generated CSI report to the base station.

[0218] In addition, the terminal can perform transmission and reception simultaneously with multiple TRPs. In the downlink, the terminal receives PDSCH from multiple TRPs. Multiple TRPs can send different layers of PDSCH in the same resources. Alternatively, multiple TRPs can send different PDSCHs to the terminal. In this case, the resources of the PDSCHs sent from multiple TRPs may or may not overlap. The above method may be referred to as non-coherent joint transmission (NCJT).

[0219] The NCJT transmission scheme can be dynamically switched to or from a single TRP transmission scheme. Therefore, the terminal can measure CSI under the assumption of multi-TRP transmission (i.e., NCJT assumption). This may be referred to as the NCJT measurement assumption. In addition, the terminal can measure CSI under the assumption of single TRP transmission. This may be referred to as the single TRP measurement assumption. The CSI based on the NCJT measurement assumption and the CSI based on the single TRP measurement assumption can be reported to the base station via one CSI report. For example, the terminal can select one (for example, the CSI corresponding to the CQI of the maximum value) between the CSI based on the NCJT measurement assumption and the CSI based on the single TRP measurement assumption, and report the selected CSI to the base station. Optionally, the terminal can report both the CSI based on the NCJT measurement assumption and the CSI based on the single TRP measurement assumption to the base station. The CSI-RS resource set configured in the terminal for the above-mentioned CSI reporting operation may include multiple CSI-RS resources, and among these CSI-RS resources, the CSI-RS resource pairs to be used for NCJT transmission may be configured separately in the terminal. Each CSI-RS resource may include unique TCI state information, and, for example, each CSI-RS resource may correspond to each TRP.

[0220] In this case, in order to improve network power efficiency, the TRP can send and receive signals by applying the TXRU muting method. Similarly, each TXRU muting pattern can correspond to each CSI report subconfiguration, and the terminal can receive a CSI report configuration including multiple subconfigurations. In this case, each CSI-RS resource can be associated with multiple subconfigurations and can correspond to at least one of the NCJT measurement hypothesis and the single TRP measurement hypothesis. For example, the first CSI-RS resource and the second CSI-RS resource belonging to the same CSI-RS resource set can be configured as a CSI resource (CMR) pair for channel measurement, and the terminal can perform CSI measurement and reporting operations according to the NCJT measurement hypothesis based on the CMR pair. At the same time, the third CSI-RS resource can be referenced for CSI measurement and reporting by a single TRP measurement hypothesis instead of being configured as a CMR pair. In this case, each subconfiguration that configures the CSI report can be associated with all CSI-RS resources and all CMR pairs that constitute the CSI-RS resource set. In the above example, each subconfiguration can be associated with a CMR pair consisting of the first CSI-RS resource and the second CSI-RS resource and the third CSI-RS resource. The terminal can measure CSI based on the NCJT measurement assumption based on the CMR pair for each subconfiguration, and can measure CSI based on the single TRP measurement assumption based on the third CSI-RS resource. The terminal can select one or more CSIs from these CSIs using the above method and report the selected CSIs to the base station. The terminal can also report the CRI corresponding to the CSI-RS resource or CMR pair on which the selected CSI is based.

[0221] The above-mentioned CSI-RS scaling method or CSI-RS muting method may correspond to the first TXRU muting method. In addition, as described above, when the TXRU is scaled by the second TXRU muting method, the number of corresponding CSI-RS antenna ports may not change. That is, even if the number of TXRUs to which the CSI-RS antenna ports are mapped changes dynamically, the terminal may receive the same CSI-RS antenna ports in the CSI-RS resources in each cycle. In the exemplary embodiment of Figure 5B, the terminal may receive the same 16 CSI-RS antenna ports before and after the TXRU is muted. That is, the 16 CSI-RS antenna ports constituting the CSI-RS resources may be sent through the first TXRU set at the first time, and may be sent through the second TXRU set at the second time.

[0222] When the TXRU is scaled from the first TXRU set to the second TXRU set using the second TXRU muting method, the mapping between each CSI-RS antenna port and the physical antenna element may change, resulting in a change in the beam pattern formed by each CSI-RS antenna port, the coverage (or signal reach or coverage), etc. Therefore, downlink measurement values, measurement quality, etc. based on the CSI-RS resources transmitted by the first TXRU set may be different from downlink measurement values, measurement quality, etc. based on the CSI-RS resources transmitted by the second TXRU set.

[0223] Therefore, if the set of TXRUs used to send CSI-RS resources changes, the base station can instruct the terminal to change the downlink measurement operation based on the CSI-RS resources. For example, the base station can instruct the terminal to reset the downlink measurement operation based on the CSI-RS resources. When a reset indication is received, the terminal can measure CSI based on the remaining CSI-RS resources excluding the CSI-RS resources received before the reset application time (e.g., the first time slot to which the reset is applied), and can report the measured CSI. Additionally, the terminal can measure and report CSI based on the CSI-RS resources received in resources no later than the CSI reference resources. Combining the above operations, the CSI report can be calculated based on the CSI-RS resources received between the reset application time (e.g., the time slot corresponding thereto) and the CSI-RS reference resources (e.g., the time slot corresponding thereto). The reset indication can be performed dynamically through DCI. For example, the DCI can be a group common DCI.

[0224] Additionally, the DCI may be a DCI indicating the CSI-RS antenna port set in (method 200) or a DCI corresponding thereto. In this case, the same CSI-RS antenna port set as before may be indicated to the terminal via the DCI. If the same CSI-RS antenna port set as before is indicated, the terminal may treat these as TXRU scaling via the second TXRU muting method and reset the CSI measurement and / or reporting operation via the above method. Optionally, the reset indication may be performed via higher layer signaling (e.g., RRC signaling, MAC CE).

[0225] As a similar method, the terminal may be configured with multiple CSI-RS antenna port sets having the same number of antenna ports and / or antenna port configurations (e.g., parameters N1 and N2). For example, a CSI-RS resource or a CSI-RS resource set may include a first CSI-RS antenna port set and a second CSI-RS antenna port set, and the first CSI-RS antenna port set and the second CSI-RS antenna port set may be the same configuration. That is, the first CSI-RS antenna port set and the second CSI-RS antenna port set may be configured with the same number of antenna ports and / or antenna ports following the same configuration (e.g., the same parameters N1 and N2). Here, the first CSI-RS antenna port set and the second CSI-RS antenna port set may mean multiple different CSI-RS resources. Multiple CSI-RS resources may be included in the CSI-RS resource set. Optionally, the first CSI-RS antenna port set and the second CSI-RS antenna port set may correspond to multiple CSI report subconfigurations corresponding to the same CSI-RS resource. The number of CSI-RS antenna ports of the first CSI-RS antenna port set and the second CSI-RS antenna port set may be the same as the number of CSI-RS antenna ports of the CSI-RS resource.

[0226] The terminal may perform a CSI reporting operation based on the first CSI-RS antenna port set or the CSI reporting configuration (or CSI reporting subconfiguration) associated therewith in a first time period. In this case, the base station may instruct the terminal to perform a CSI reporting operation based on the second CSI-RS antenna port set or the CSI reporting configuration (or CSI reporting subconfiguration) associated therewith. For example, the instruction may be performed via DCI. When instructed to switch from the first CSI-RS antenna port set (or the corresponding CSI reporting configuration or CSI reporting subconfiguration) to the second CSI-RS antenna port set (or the corresponding CSI reporting configuration or CSI reporting subconfiguration), the terminal may reset the CSI measurement or calculation operation. Optionally, the terminal may distinguish between a first CSI measurement and reporting operation for the first CSI-RS antenna port set (or the corresponding CSI reporting configuration or CSI reporting subconfiguration) and a second CSI measurement and reporting operation for the second CSI-RS antenna port set (or the corresponding CSI reporting configuration or CSI reporting subconfiguration). The first CSI measurement and reporting operation may correspond to a first CSI-RS antenna port virtualization or beamforming, and the second CSI measurement and reporting operation may correspond to a second CSI-RS antenna port virtualization or beamforming. According to the above method, the terminal and the base station may respond to beam or coverage changes according to the second TXRU muting method.

[0227] For example, the terminal may receive a CSI report configuration including a first CSI report subconfiguration and a second CSI report subconfiguration. The first CSI report subconfiguration may indicate a CSI measurement and reporting operation for a CSI-RS antenna port set sent through a first virtualization or a first TXRU set, and the second CSI report subconfiguration may indicate a CSI measurement and reporting operation for a CSI-RS antenna port set sent through a second virtualization and a second TXRU set. To this end, the first CSI report subconfiguration and the second CSI report subconfiguration may be associated with the first CSI-RS resource and the second CSI-RS resource, respectively. According to the above method, the first CSI-RS resource and the second CSI-RS resource may be included in the same CSI-RS resource set and may be configured with the same number of CSI-RS antenna ports. The transmission period and periodicity of the first CSI-RS resource and the second CSI-RS resource may be the same.

[0228] On the other hand, the set of REs to which the CSI-RS resources are mapped and their mapping patterns may be different between the first CSI-RS resource and the second CSI-RS resource. Specifically, each of the first CSI-RS resource and the second CSI-RS resource may be mapped to an RE according to a mapping pattern based on an independent CSI-RS resource configuration. However, considering the above-mentioned second TXRU silent operation, it may be sufficient to map the first CSI-RS resource and the second CSI-RS resource on the same resource based on the same mapping pattern. For example, the first CSI-RS resource and the second CSI-RS resource may be configured to completely overlap, and the set of mapped REs and the RE mapping patterns used therefor may also match. That is, the first CSI-RS resource and the second CSI-RS resource may not be physically distinguished, but may be logically distinguished only by being referenced by different CSI report sub-configurations.

[0229] As described above, each of a plurality of different CSI resources can be counted from the perspective of the CPU. Accordingly, the first CSI-RS resource and the second CSI-RS resource can occupy two CPUs. However, considering the second TXRU silencing method, the terminal may not simultaneously perform the CSI measurement and reporting operation for the first CSI-RS resource and the CSI measurement and reporting operation for the second CSI-RS resource. That is, the terminal may receive the first CSI-RS resource for CSI measurement in the first time period, and may receive the second CSI-RS resource for CSI measurement in the second time period. The first time period and the second time period may not overlap. The above-mentioned signaling method may be used to indicate to the terminal to switch from the first time period to the second time period, or from the second time period to the first time period. In this case, the CSI calculation complexity of the terminal in each of the first time period and the second time period may correspond to the CSI measurement operation corresponding to one CSI-RS resource. That is, the actual CSI measurement operation of the terminal in the first time period may occupy one CPU, and similarly, the actual CSI measurement operation of the terminal in the second time period may occupy one CPU.

[0230] Therefore, in the proposed method, the first CSI-RS resource and the second CSI-RS resource can occupy one CPU. That is, the first CSI-RS resource and the second CSI-RS resource may not be counted separately from the perspective of the CPU and may be counted only once. Optionally, only one of the first CSI-RS resource and the second CSI-RS resource can occupy the CPU. For example, one of the CSI-RS resources can be determined based on the CSI-RS resource index or the associated CSI report subconfiguration index. This method can be applied only when the above conditions are met, that is, when the first CSI-RS resource and the second CSI-RS resource are referenced by different CSI report subconfigurations. Different CSI report subconfigurations may be subconfigurations included in the same CSI report configuration. In addition, the conditions for applying the method may also include the condition that the first CSI-RS resource and the second CSI-RS resource overlap (for example, completely overlap), the condition that the RE mapping of the first CSI-RS resource and the second CSI-RS resource is the same, etc. According to the proposed method, the terminal's CPU can be calculated to reflect the terminal's actual CSI calculation complexity, and the terminal can use the remaining CPU to perform additional CSI measurement and reporting operations in the corresponding period, for example, CSI measurement and reporting operations for the third CSI-RS resource. The third CSI-RS resource can be referenced by the first CSI reporting subconfiguration or the second CSI reporting subconfiguration. Optionally, the third CSI-RS resource can be referenced by a CSI reporting subconfiguration or a CSI reporting configuration other than the first and second CSI reporting subconfigurations.

[0231] Similarly, the CSI-RS antenna ports constituting the first CSI-RS resource and the CSI-RS antenna ports constituting the second CSI-RS resource may not be redundantly counted as active CSI-RS antenna ports. That is, when the first CSI-RS resource and the second CSI-RS resource consist of R CSI-RS antenna ports, the number of corresponding active CSI-RS antenna ports may be R instead of 2*R. For example, the CSI-RS antenna ports constituting only one of the first CSI-RS resource and the second CSI-RS resource may be counted as active CSI-RS antenna ports. Similarly, a CSI-RS resource may be determined based on a CSI-RS resource index or an associated CSI report subconfiguration index.

[0232] In addition, when the terminal is configured to limit CSI measurement resources, the terminal can measure CSI based on one CSI-RS resource (or CSI-RS instance). In this case, even if the TXRU to which the CSI-RS antenna port is connected changes, the terminal's CSI measurement and reporting operations can be performed unchanged. In view of this, a method can be considered to limit the use of the second TXRU muting method to the case where the terminal performs CSI measurement operations using limited CSI measurement resources.

[0233] The above-mentioned CSI-RS scaling or muting methods can be basically applied to periodic CSI-RS and semi-persistent CSI-RS. In addition, the above-mentioned corresponding CSI reporting methods can be applied to periodic CSI reporting, semi-persistent CSI reporting, and aperiodic CSI reporting procedures. In the case of aperiodic CSI-RS, the terminal can be configured with multiple CSI-RS resources of a CSI-RS resource set and can be dynamically instructed via DCI to receive one of the multiple CSI-RS resources. In this case, each CSI-RS resource can correspond to the above-mentioned CSI-RS antenna port set.

[0234] For ZP CSI-RS and CSI-interference measurement (IM), the above-mentioned CSI-RS scaling or muting method can be performed in the same or similar manner. For example, in the above-mentioned exemplary embodiment, the CSI-RS resource can be replaced with a ZP CSI-RS resource, and the CSI-RS antenna port set can be replaced with a ZP CSI-RS antenna port set. According to the above-mentioned method, the terminal can configure one or more ZP CSI-RS antenna port sets for the ZP CSI-RS resource, and perform a rate matching operation (e.g., a PDSCH rate matching operation) for one or more ZP CSI-RS antenna port sets. That is, the PDSCH can be mapped to a resource that does not include the RE to which the ZP CSI-RS antenna port set is mapped, and can be sent to the terminal. For another example, in the above-mentioned exemplary embodiment, the CSI-RS resource can be replaced with a CSI-IM resource (or, NZP CSI-IM resource), and the CSI-RS antenna port set can be replaced with a CSI-IM antenna port set (or, NZP CSI-IM antenna port set). The terminal can perform an interference measurement operation in the CSI-IM antenna port set. For ZP CSI-RS and CSI-IM, the above-mentioned CSI-RS scaling or muting method can be performed in the same or similar manner. For example, in the above-mentioned exemplary embodiment, the CSI-RS resource can be replaced with a ZP CSI-RS resource, and the CSI-RS antenna port set can be replaced with a ZP CSI-RS antenna port set. According to the above-mentioned method, the terminal can configure one or more ZP CSI-RS antenna port sets for the ZP CSI-RS resource, and perform a rate matching operation (e.g., a PDSCH rate matching operation) for one or more ZP CSI-RS antenna port sets. That is, the PDSCH can be mapped to a resource that does not include the RE to which the ZP CSI-RS antenna port set is mapped, and can be sent to the terminal. For another example, in the above-mentioned exemplary embodiment, the CSI-RS resource can be replaced with a CSI-IM resource (or, NZP CSI-IM resource), and the CSI-RS antenna port set can be replaced with a CSI-IM antenna port set (or, NZP CSI-IM antenna port set). The terminal can perform interference measurement operations in the CSI-IM antenna port set.

[0235] The operation of the method according to the exemplary embodiment of the present disclosure can be implemented as a computer-readable program or code in a computer-readable recording medium. The computer-readable recording medium may include all kinds of recording devices for storing data that can be read by a computer system. In addition, the computer-readable recording medium can store and execute a program or code that can be distributed in a computer system connected via a network and read by a computer in a distributed manner.

[0236] The computer readable recording medium may include a hardware device specifically configured to store and execute program commands, such as ROM, RAM, or flash memory. The program commands may include not only machine language codes created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter.

[0237] Although some aspects of the present disclosure have been described in the context of a device, these aspects can indicate the corresponding description according to the method, and a block or device can correspond to the step of the method or the feature of the step. Similarly, the aspect described in the context of the method can be expressed as the feature of a corresponding block or item or a corresponding device. Some or all steps of the method can be performed by (or using) a hardware device such as a microprocessor, a programmable computer or an electronic circuit. In certain embodiments, one or more of the most important steps of the method can be performed by such a device.

[0238] In some exemplary embodiments, a programmable logic device such as a field programmable gate array (FPGA) may be used to perform some or all of the functions of the methods described herein. In some exemplary embodiments, the FPGA may be operated with a microprocessor to perform one of the methods described herein. Typically, the methods are preferably performed by specific hardware devices.

[0239] The description of the present disclosure is merely exemplary in nature, and therefore, variations that do not depart from the essence of the present disclosure are intended to fall within the scope of the present disclosure. These variations should not be considered as departing from the spirit and scope of the present disclosure. Therefore, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope defined by the appended claims.

Claims

1. A terminal method, comprising: receiving first configuration information about a first channel state information-reference signal CSI-RS resource from a base station; receiving second configuration information for a CSI reporting operation from the base station; receiving, based on the first configuration information and the second configuration information, a CSI-RS through M CSI-RS antenna ports, where the M CSI-RS antenna ports are a first subset of L CSI-RS antenna ports corresponding to the first CSI-RS resource, where L is a natural number and M is a natural number equal to or less than L; Determine a first precoding matrix indicator PMI based on the M CSI-RS antenna ports; and sending a CSI report including the first PMI to the base station, The determination of the first PMI is performed based on a codebook, wherein in the codebook, sizes of at least the first dimension and the second dimension are N1 and N2 respectively, and N1 and N2 are each determined as a divisor of M.

2. The method according to claim 1, wherein The second configuration information includes configuration information of multiple CSI reporting subconfigurations, the first CSI-RS resource is referenced by a first CSI reporting subconfiguration included in the multiple CSI reporting subconfigurations, and the first PMI is CSI corresponding to the first CSI reporting subconfiguration.

3. The method according to claim 2, wherein: The second CSI-RS resource is additionally referenced by the first CSI reporting subconfiguration, the CSI corresponding to the first CSI reporting subconfiguration includes a CSI-RS resource indicator CRI, and the CRI is an index of the first CSI-RS resource or the second CSI-RS resource.

4. The method according to claim 3, wherein: The second CSI-RS resources correspond to L CSI-RS antenna ports and belong to the same CSI-RS resource set as the first CSI-RS.

5. The method according to claim 1, wherein The M CSI-RS antenna ports are represented as a bitmap of length L, and the bitmap is transmitted from the base station to the terminal when included in the second configuration information.

6. The method according to claim 1, wherein The antenna port numbers of the M CSI-RS antenna ports are reallocated in ascending order of consecutive values ​​from P to (P+M-1), where P is 0 or a natural number, and the first PMI is determined based on the reallocated antenna port numbers.

7. The method according to claim 1, wherein M=2*N1*N2, N1 is a value based on the number of CSI-RS antenna ports corresponding to the first dimension, and N2 is a value based on the number of CSI-RS antenna ports corresponding to the second dimension.

8. The method according to claim 1, wherein M=2*N1*N2*Ng, where N1 is a value based on the number of CSI-RS antenna ports corresponding to the first dimension, N2 is a value based on the number of CSI-RS antenna ports corresponding to the second dimension, Ng is the number of antenna panels, and the codebook is a codebook for multiple panels consisting of Ng panels.

9. The method according to claim 2, further comprising: receiving CSI-RS via M2 CSI-RS antenna ports, wherein the M2 CSI-RS antenna ports are a second subset of the L CSI-RS antenna ports; and A second PMI is determined based on the M2 CSI-RS antenna ports.

10. The method according to claim 9, wherein: The second PMI is included in the CSI report and is sent to the base station based on an instruction of a higher layer message.

11. The method according to claim 9, wherein The first CSI-RS resource is referenced by a second CSI reporting subconfiguration included in the multiple CSI reporting subconfigurations, and the second PMI is CSI corresponding to the second CSI reporting subconfiguration.

12. A method for a base station, comprising: Sending first configuration information about a first channel state information-reference signal CSI-RS resource to the terminal; Sending second configuration information for CSI reporting to the terminal; transmitting a CSI-RS to the terminal through all or part of L CSI-RS antenna ports corresponding to the first CSI-RS resource, where L is a natural number; and receiving, from the terminal, a CSI report including a first precoding matrix indicator (PMI) determined based on M CSI-RS antenna ports, wherein the M CSI-RS antenna ports are a first subset of the L CSI-RS antenna ports determined based on the first configuration information and the second configuration information; The first PMI is determined based on a codebook, wherein in the codebook, sizes of at least a first dimension and a second dimension are N1 and N2, respectively, and N1 and N2 are each determined as a divisor of M.

13. The method according to claim 12, wherein: The second configuration information includes configuration information of multiple CSI reporting subconfigurations, the first CSI-RS resource is referenced by a first CSI reporting subconfiguration included in the multiple CSI reporting subconfigurations, and the first PMI is CSI corresponding to the first CSI reporting subconfiguration.

14. The method according to claim 13, wherein The second CSI-RS resource is additionally referenced by the first CSI reporting subconfiguration, the CSI corresponding to the first CSI reporting subconfiguration includes a CSI-RS resource indicator CRI, and the CRI is an index of the first CSI-RS resource or the second CSI-RS resource.

15. The method according to claim 14, wherein The second CSI-RS resources correspond to L CSI-RS antenna ports and belong to the same CSI-RS resource set as the first CSI-RS.

16. The method according to claim 12, wherein: The M CSI-RS antenna ports are represented as a bitmap of length L, and the bitmap is transmitted from the base station to the terminal when included in the second configuration information.

17. The method according to claim 12, wherein: The antenna port numbers of the M CSI-RS antenna ports are reallocated in ascending order of consecutive values ​​from P to (P+M-1), where P is 0 or a natural number, and the first PMI is determined based on the reallocated antenna port numbers.

18. The method according to claim 12, wherein: M=2*N1*N2, N1 is a value based on the number of CSI-RS antenna ports corresponding to the first dimension, and N2 is a value based on the number of CSI-RS antenna ports corresponding to the second dimension.

19. The method according to claim 12, wherein: M=2*N1*N2*Ng, where N1 is a value based on the number of CSI-RS antenna ports corresponding to the first dimension, N2 is a value based on the number of CSI-RS antenna ports corresponding to the second dimension, Ng is the number of antenna panels, and the codebook is a codebook for multiple panels consisting of Ng panels.

20. A terminal comprising a processor, wherein: The processor causes the terminal to perform the following operations: receiving first configuration information about a first channel state information-reference signal CSI-RS resource from a base station; receiving second configuration information for a CSI reporting operation from the base station; receiving, based on the first configuration information and the second configuration information, a CSI-RS through M CSI-RS antenna ports, where the M CSI-RS antenna ports are a first subset of L CSI-RS antenna ports corresponding to the first CSI-RS resource, where L is a natural number and M is a natural number equal to or less than L; Determine a first precoding matrix indicator PMI based on the M CSI-RS antenna ports; and sending a CSI report including the first PMI to the base station, The determination of the first PMI is performed based on a codebook, wherein in the codebook, sizes of at least the first dimension and the second dimension are N1 and N2 respectively, and N1 and N2 are each determined as a divisor of M.

Images