User equipment, base station and method in communication system

Abstract

The present disclosure relates to communication technologies and systems for 5G communication systems that integrate IoT technologies and support higher data transmission rates than 4G systems. The present disclosure can be applied to smart services based on 5G communication technologies and IoT-related technologies (such as smart homes, smart buildings, smart cities, smart or connected cars, healthcare, digital education, retail businesses, and services related to security and safety). The present disclosure relates to a method for indicating a diversity-based data transmission method from a base station to a terminal, as well as related data transmission methods.

Description

[0001] This application is a divisional application of the invention patent application with the application date of April 3, 2018, application number 201880029675.5, and invention name “Method and device for diversity-based data transmission in mobile communication system”. Technical Field

[0002] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting a diversity-based signal, a method and apparatus for configuring a demodulation reference signal (DMRS), and a method and apparatus for configuring a reference signal for measuring a channel state. Background Art

[0003] In order to meet the increased demand for wireless data services after the commercialization of 4G communication systems, efforts have been made to develop improved 5G communication systems or pre-5G communication systems. Therefore, the 5G communication system or the communication system before 5G is called a super 4G network communication system or a post-LTE system. In order to achieve high data transmission rates, the implementation of 5G communication systems in millimeter wave bands (such as 60GHz bands) is being considered. In 5G communication systems, technologies such as beamforming, massive MIMO, full-size MIMO (FD-MIMO), array antennas, analog beamforming and massive antennas are being discussed as a means of reducing propagation path loss in millimeter wave bands and increasing propagation transmission distances. In addition, 5G communication systems have developed technologies such as evolved small cells, advanced small cells, cloud radio access networks (RAN), ultra-dense networks, device-to-device communication (D2D), wireless backhaul, mobile networks, collaborative communications, coordinated multipoint (CoMP) and reception interference cancellation to improve system networks. In addition, 5G systems have developed: advanced coding and modulation (ACM) schemes, such as hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC); and advanced access technologies, such as filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA).

[0004] Meanwhile, the Internet has evolved into the Internet of Things (IoT), where distributed components such as objects exchange and process information from a network of connected, human-oriented devices, where humans generate and consume information. The Internet of Everything (IoE) has emerged, combining big data processing technologies with IoT technology through connections to cloud servers and other platforms. Implementing the IoT requires technological factors such as sensing, wired and wireless communications, network infrastructure, service interface technologies, and security. Recently, research has been underway on technologies for connecting objects, such as sensor networks, machine-to-machine (M2M) communications, and machine-type communications (MTC). In the IoT, by collecting and analyzing data generated by connected objects, intelligent Internet technology (IT) services can be provided to create new value for people's lives. By integrating traditional information technology (IT) with various industries, the IoT can be applied to areas such as smart homes, smart buildings, smart cities, smart cars, connected vehicles, smart grids, healthcare, smart appliances, and high-tech medical services.

[0005] Therefore, various attempts have been made to apply 5G communication systems to IoT networks. For example, beamforming, MIMO, and array antenna schemes are being used to implement 5G communication technologies such as sensor networks, machine-to-machine (M2M) communication, and machine-type communication (MTC). The application of cloud RAN, a big data processing technology, may be an example of the convergence of 5G and IoT technologies.

[0006] In the recently studied fifth-generation mobile communication system (or New Radio (NR)), research is being conducted on applying diversity schemes to uplink transmission of UEs. In addition, the transmission of reference signals is required to demodulate signals through channel estimation, and in NR systems, demodulation reference signals (DMRS) that can be configured to support increased channel bandwidth and various parameter sets are being considered. In addition, in order to reduce the overhead of the channel state information reference signal (CSI-RS), aperiodic CSI-RS transmission and a configuration method based on the same have been studied. Summary of the Invention

[0007] Technical issues

[0008] The present disclosure proposes a method of transmitting a signal through a diversity scheme and a method of instructing diversity transmission in an uplink.

[0009] The present disclosure proposes a method for generating a DMRS sequence reflecting various considerations of a 5G wireless communication system, a method for mapping the DMRS sequence, and detailed parameters based thereon.

[0010] The present disclosure proposes a method for transmitting and configuring an aperiodic CSI-RS in a wireless communication system, and a method and apparatus for determining a bandwidth for aperiodic CSI-RS measurement.

[0011] Solution

[0012] According to aspects of the present disclosure, a method for transmitting a channel state information reference signal (CSI-RS) by a base station (BS) in a wireless communication system is provided. The method includes: transmitting CSI-RS configuration information including configuration of CSI-RS resources; transmitting downlink control information to a user equipment (UE), the downlink control information including trigger information indicating at least one CSI-RS resource among the CSI-RS resources; and transmitting the CSI-RS to the UE according to the at least one CSI-RS resource. The downlink control information may further include information indicating a bandwidth of the at least one CSI-RS resource, the bandwidth indication information indicating one of a CSI-RS bandwidth configured by a higher layer and a predefined bandwidth, the predefined bandwidth may be a bandwidth part, a UE bandwidth, or a system bandwidth, and the downlink control information may further include information indicating a bandwidth of a zero-power (ZP) CSI-RS.

[0013] According to another aspect of the present disclosure, a method for receiving a channel state information reference signal (CSI-RS) by a user equipment (UE) in a wireless communication system is provided. The method includes: receiving CSI-RS configuration information including configuration of CSI-RS resources from a base station (BS); receiving downlink control information from the BS, the downlink control information including trigger information indicating at least one CSI-RS resource among the CSI-RS resources; and receiving the CSI-RS from the BS according to the at least one CSI-RS resource.

[0014] According to another aspect of the present disclosure, a base station (BS) for transmitting a channel state information reference signal (CSI-RS) in a wireless communication system is provided. The BS includes: a transceiver; and a controller configured to perform control to transmit CSI-RS configuration information including configuration of CSI-RS resources, transmit downlink control information including trigger information indicating at least one CSI-RS resource among CSI-RS resources to a user equipment (UE), and transmit the CSI-RS to the UE based on the at least one CSI-RS resource, the controller being connected to the transceiver.

[0015] According to another aspect of the present disclosure, a user equipment (UE) for receiving a channel state information reference signal (CSI-RS) in a wireless communication system is provided. The UE includes: a transceiver; and a controller configured to perform control to receive CSI-RS configuration information including configuration of CSI-RS resources from a base station (BS), receive downlink control information from the BS, the downlink control information including trigger information indicating at least one CSI-RS resource among the CSI-RS resources, and receive a CSI-RS from the BS according to the at least one CSI-RS resource, the controller being connected to the transceiver.

[0016] According to another aspect of the present disclosure, a method performed by a user equipment (UE) in a communication system is provided, the method comprising: receiving configuration information about aperiodic channel state information (CSI) reporting from a base station; receiving downlink control information (DCI) including an information field for triggering aperiodic CSI from the base station; receiving a CSI reference signal (CSI-RS) from the base station based on a CSI-RS offset identified based on higher layer signaling; and sending an aperiodic CSI report including CSI generated based on the CSI-RS to the base station.

[0017] According to another aspect of the present disclosure, a method performed by a base station in a communication system is provided, the method comprising: sending configuration information about aperiodic channel state information (CSI) reporting to a user equipment (UE); sending downlink control information (DCI) including an information field for triggering aperiodic CSI to the UE; sending a CSI reference signal (CSI-RS) to the UE based on a CSI-RS offset, wherein the CSI-RS offset is notified to the UE based on higher layer signaling; and receiving an aperiodic CSI report from the UE including CSI generated based on the CSI-RS.

[0018] According to another aspect of the present disclosure, a user equipment (UE) in a communication system is provided, the UE including: a transceiver, and; a controller configured to: receive configuration information about aperiodic channel state information (CSI) reporting from a base station; receive downlink control information (DCI) including an information field for triggering aperiodic CSI from the base station; receive a CSI reference signal (CSI-RS) from the base station based on a CSI-RS offset identified based on higher layer signaling; and send an aperiodic CSI report including CSI generated based on the CSI-RS to the base station.

[0019] According to another aspect of the present disclosure, a base station in a communication system is provided, the base station including: a transceiver; and a controller configured to: send configuration information about aperiodic channel state information (CSI) reporting to a user equipment (UE); send downlink control information (DCI) including an information field for triggering aperiodic CSI to the UE; send a CSI reference signal (CSI-RS) to the UE based on a CSI-RS offset, wherein the CSI-RS offset is notified to the UE based on higher layer signaling; and receive an aperiodic CSI report including CSI generated based on the CSI-RS from the UE.

[0020] Advantageous Effects of the Invention

[0021] According to the embodiments of the present disclosure, it is possible to efficiently use radio resources by using the method of transmitting signals using an uplink diversity scheme and the method of configuring signals when performing uplink transmission proposed by the present disclosure. According to the embodiments of the present disclosure, it is possible to efficiently demodulate signals and efficiently use radio resources by using the various DMRS structures, DMRS sequence mapping methods, and DMRS sequence initialization methods according to the present disclosure. According to the embodiments of the present disclosure, it is possible to improve the transmission efficiency of reference signals by base stations and UEs including multiple antennas and to expect an increase in system throughput. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 shows a basic structure of a time / frequency region, which is a radio resource region in which data or a control channel is transmitted in a downlink of an LTE system;

[0023] Figure 2 shows a basic structure of a time-frequency region according to the prior art, which is a radio resource region in which data or a control channel is transmitted in an uplink of an LTE system;

[0024] Figure 3 and Figure 4 An example of allocating data for eMBB, URLLC, and mMTC, which are considered services in the system, to frequency-time regions is shown;

[0025] Figure 5 Examples of uplink transmissions with dynamic beamforming and semi-dynamic beamforming are shown;

[0026] Figure 6 An example is shown in which a UE and a base station transmit reference signals in order to acquire channel state information required for uplink transmission in an NR system.

[0027] Figure 7 An example of allocating resources for uplink transmission and applying subband precoding is shown;

[0028] Figure 8 FIG. 1 shows a method of applying different precoding methods proposed in this embodiment to REs assuming that two DMRS ports are used;

[0029] Figure 9 An example is shown in which a precoder is applied to a different RE-specific mapping for each symbol to increase diversity gain;

[0030] Figure 10 Shown Figure 8 The precoder loop method shown and Figure 9 Comparison between the performance of the precoder loop methods shown;

[0031] Figure 11A and Figure 11B An example of applying another precoding in a time resource unit based on the assumption that the same number of DMRS ports as the number of transmitted ranks is used is shown;

[0032] Figure 12 An example of a precoder cycle in time units is shown based on the assumption that DMRS is transmitted in one complete symbol;

[0033] Figure 13 An example of applying different precoding to RBs or PRGs based on the assumption that two DMRS ports are used is shown;

[0034] Figure 14A An example of using a codebook for diversity-based transmission is shown;

[0035] Figure 14B An example of operations for activating SRS candidate resources through a MAC CE and actually activating the SRS candidate resources through a DCI is shown;

[0036] Figure 15 shows time and frequency resources used by multiple UEs to transmit uplink data;

[0037] Figure 16 is a block diagram illustrating an internal structure of a UE according to an embodiment of the present disclosure;

[0038] Figure 17 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure;

[0039] Figure 18 shows the basic structure of the time-frequency region, which is a radio frequency region in which data or control channels are transmitted in the downlink of the LTE system;

[0040] Figure 19shows the basic structure of a time-frequency region, which is a radio frequency region in which data or control channels are transmitted in the uplink of an LTE system;

[0041] Figure 20 shows a radio resource of one RB which is the minimum unit of scheduling in the downlink of the LTE system;

[0042] Figure 21 An example of a method for generating a DMRS is shown;

[0043] Figure 22A An example of a unit DMRS structure proposed by the present disclosure is shown;

[0044] Figure 22B An example of arranging a DC subcarrier according to the DMRS structure proposed in the present disclosure is shown;

[0045] Figure 23 Shows the mapping of antenna ports to Figure 22A An example of the proposed method for unit DMRS structure;

[0046] Figure 24 shows that a larger number of antenna ports are mapped to Figure 23 An example of the proposed method for unit DMRS structure;

[0047] Figure 25 1. The position of the front-loaded DMRS is shown when the slot length is 7 or 14 OFDM symbols;

[0048] Figure 26 Shows the location where the extended DMRS is transmitted when the slot length is 7 or 14 OFDM symbols;

[0049] Figure 27 An example of a two-step resource allocation method is shown;

[0050] Figure 28 An example of a mode available in Type 1 according to the antenna port mapping method is shown;

[0051] Figure 29 An example of a mode available in Type 2 according to the antenna port mapping method is shown;

[0052] Figure 30 An example of DMRS transmission for Type 1 DMRS pattern is shown;

[0053] Figure 31 FIG2 shows the actions of the base station and the UE according to this embodiment;

[0054] Figure 32is a block diagram illustrating an internal structure of a UE according to an embodiment of the present disclosure;

[0055] Figure 33 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure;

[0056] Figure 34 An FD-MIMO system to which an embodiment of the present disclosure is applied is shown;

[0057] Figure 35 shows radio resources corresponding to one subframe and one RB, which are minimum units that can be scheduled to a downlink in LTE and LTE-A systems;

[0058] Figure 36 An example of CSI-RS RE mapping for the nth and n+1th PRBs is shown in the case where the base station transmits CSI-RSs for eight antenna ports;

[0059] Figure 37 An example of BF CSI-RS operation is shown;

[0060] Figure 38 An example of CSI-RS transmission / reception and CSI reporting therefrom is shown;

[0061] Figure 39 An example of a dynamic port numbering operation scenario for aperiodic CSI-RS is shown;

[0062] Figure 40 Another example of a dynamic port numbering operation scenario for aperiodic CSI-RS is shown;

[0063] Figure 41 An example of CSI-RS resource configuration information is shown;

[0064] Figure 42 Another example of CSI-RS resource configuration information is shown;

[0065] Figure 43 An example of a second method for configuring and changing a CSI-RS transmission band is shown;

[0066] Figure 44 shows a process in which the UE performs bandwidth adaptation by transmission band change signaling;

[0067] Figure 45 The process of controlling the aperiodic CSI-RS transmission and reception bands through control channel CSI trigger signaling is shown;

[0068] Figure 46 A process for controlling the aperiodic ZP CSI-RS transmission and reception bands is shown;

[0069] Figure 47 FIG4 shows an operation of a base station for transmitting an aperiodic CSI-RS;

[0070] Figure 48 1. The operation of the UE for receiving the aperiodic CSI-RS is shown;

[0071] Figure 49 is a block diagram illustrating an internal structure of a UE according to an embodiment of the present disclosure; and

[0072] Figure 50 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0073] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0074] When describing the exemplary embodiments of the present disclosure, descriptions related to technical contents that are well-known in the art to which the present disclosure belongs and are not directly related to the present disclosure will be omitted. Such omission of unnecessary descriptions is intended to prevent the main idea of ​​the present disclosure from being obscured and to convey the main idea more clearly.

[0075] For the same reason, in the accompanying drawings, some elements may be enlarged, omitted or schematically shown. In addition, the size of each element does not fully reflect the actual size. In the accompanying drawings, the same or corresponding elements are provided with the same reference numerals.

[0076] The advantages and features of the present disclosure and the manner in which they are achieved will become apparent by reference to the embodiments described in detail below in conjunction with the accompanying drawings. However, the present disclosure is not limited to the embodiments set forth below, but may be implemented in various forms. The following embodiments are provided only to fully disclose the present disclosure and to inform those skilled in the art of the scope of the present disclosure, and the present disclosure is limited only by the scope of the appended claims. Throughout the specification, the same or similar reference numerals indicate the same or similar elements.

[0077] It will be understood that each block of the flowchart illustration, as well as the combination of blocks in the flowchart illustration, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine, such that the instructions executed by the processor of the computer or other programmable data processing device create a device for implementing the functions specified in one or more flowchart blocks. These computer program instructions can also be stored in a computer-usable or computer-readable memory, which can instruct the computer or other programmable data processing device to act in a specific manner, such that the instructions stored in the computer-usable or computer-readable memory produce an article of manufacture including an instruction device that implements the functions specified in one or more flowchart blocks. The computer program instructions can also be loaded onto a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, such that the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one or more flowchart blocks.

[0078] Furthermore, each block of the flowchart diagram may represent a module, fragment, or portion of code that includes one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions mentioned in the blocks may not occur in sequence. For example, two blocks shown in succession may actually be run substantially simultaneously, or blocks may sometimes be run in reverse order, depending on the functions involved.

[0079] When used in this article, "unit" refers to a software element or hardware element that performs a predetermined task, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC). However, "unit" does not always have the meaning of being limited to software or hardware. A "unit" can be constructed to be stored in an addressable storage medium or run on one or more processors. Therefore, a "unit" includes, for example, software elements, object-oriented software elements, class elements and task elements, processing, functions, attributes, processes, subroutines, program code fragments, drivers, firmware, microcodes, circuits, data, databases, data structures, tables, arrays and variables. The elements and functions provided by a "unit" can be combined into "units" of fewer elements, or divided into units of a larger number of elements. In addition, elements and units can be implemented as reproducing one or more CPUs in a device or a secure multimedia card. The present disclosure can have various modifications and various embodiments, wherein specific embodiments will now be described more fully with reference to the accompanying drawings. However, it should be understood that it is not intended to limit the present disclosure to the specific form disclosed, but on the contrary, the present disclosure will cover all modifications, equivalents and alternative forms that fall within the spirit and scope of the present disclosure.

[0080] Furthermore, it will be understood that singular expressions such as "a," "an," and "the" also include plural expressions unless the context clearly indicates otherwise. Thus, as an example, "a component surface" includes one or more component surfaces.

[0081] Although terms including ordinal numbers such as first, second, etc. can be used to describe various elements, structural elements are not subject to the constraints of these terms. These terms are only used to distinguish one element from other elements. For example, without departing from the scope of this disclosure, a first element can be referred to as a second element, and similarly, a second element can also be referred to as a first element. When used in this article, the term "and / or" includes any and all combinations of one or more associated items.

[0082] The terms used herein are only used to describe specific embodiments and are not intended to limit the present disclosure. When used herein, the singular form is also intended to include the plural form, unless the context clearly indicates otherwise. In the present disclosure, terms such as "including" and / or "having" may be interpreted as indicating certain characteristics, quantities, steps, operations, constituent elements, parts or combinations thereof, but may not be interpreted as excluding the possibility of the presence or addition of one or more other characteristics, quantities, steps, operations, constituent elements, components or combinations thereof.

[0083] Hereinafter, all embodiments of the present disclosure may not be exclusive, and one or more embodiments may be performed together. However, for the sake of convenience of description, embodiments and examples will be described separately.

[0084] <First embodiment>

[0085] Wireless communication systems have evolved into broadband wireless communication systems that provide high-speed and high-quality packet data services beyond the voice-based services provided in the initial stages, such as communication standards such as 3GPP's High Speed ​​Packet Access (HSPA), Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA), LTE-Advanced (LTE-A), 3GPP2's High Rate Packet Data (HRPD), Ultra Mobile Broadband (UMB), and IEEE's 802.16e. 5G or New Radio (NR) communication standards are under study as fifth-generation wireless communication systems.

[0086] The LTE system, which is a representative example of a broadband wireless communication system, utilizes an orthogonal frequency division multiplexing (OFDM) scheme for the downlink (DL) and a single carrier frequency division multiple access (SC-FDMA) scheme for the uplink (UL). The uplink is a radio link through which a user equipment (UE) (or mobile station (MS)) sends data or control signals to a base station (BS) (or eNode B (eNB)), and the downlink is a radio link through which a base station sends data or control signals to a UE. In this multiple access scheme, time-frequency resources used to carry data or control information are allocated and operated in a manner to prevent overlap of resources between users (i.e., to establish orthogonality) so as to identify the data or control information of each user. Hereinafter, the LTE system may include LTE and LTE-A systems.

[0087] In the event of a decoding failure during initial transmission, the LTE system utilizes Hybrid Automatic Repeat Request (HARQ), which retransmits the corresponding data at the physical layer. In the HARQ scheme, when the receiver fails to accurately decode the data, it sends information (a negative acknowledgement: NACK) to inform the transmitter of the decoding failure, allowing the transmitter to retransmit the corresponding data at the physical layer. The receiver combines the data retransmitted by the transmitter with the previously decoded data, thereby improving data reception performance. Furthermore, when the receiver accurately decodes the data, it sends information (an acknowledgment: ACK) to inform the transmitter of the decoding success, allowing the transmitter to send new data.

[0088] Figure 1 1 shows a basic structure of a time / frequency region which is a radio resource region in which data or a control channel is transmitted in a downlink of an LTE system.

[0089] exist Figure 1 In FIG. 1 , the horizontal axis indicates the time domain and the vertical axis indicates the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol. One time slot 106 consists of N symb OFDM symbols 102, and one subframe 105 consists of two time slots. The length of one time slot is 0.5 ms (milliseconds), and the length of one subframe is 1.0 ms. A radio frame 114 is a time region interval consisting of 10 subframes. The minimum transmission unit in the frequency region is a subcarrier, and the bandwidth of the entire system transmission band consists of a total of N BW It consists of 104 subcarriers.

[0090] The basic unit of resources in the time-frequency domain is a resource element (RE) 112 and can be indicated by an OFDM symbol index and a subcarrier index. A resource block (RB or physical resource block (PRB)) 108 consists of N symbconsecutive OFDM symbols 102 and N in the frequency domain RB Thus, one RB 108 is defined by N consecutive subcarriers 110. symb ×N RB The minimum transmission unit of data is RB. symb =7 and N RB =12. N BW Proportional to the bandwidth of the system transmission band. The data rate increases in proportion to the number of RBs scheduled in the UE.

[0091] The LTE system defines and operates six transmission bandwidths. In the case of a frequency division duplex (FDD) system that operates by separating the downlink and uplink by frequency, the downlink transmission bandwidth and the uplink transmission bandwidth may be different from each other. The channel bandwidth may indicate the RF bandwidth corresponding to the system transmission bandwidth. [Table 1] shows the relationship between the system transmission bandwidth and the channel bandwidth defined in the LTE system. For example, when the LTE system has a channel bandwidth of 10 MHz, the transmission bandwidth may consist of 50 RBs.

[0092] [Table 1]

[0093] Channel bandwidth BWChannel[MHz] 1.4 3 5 10 15 20 Transmission bandwidth configuration NRB 6 15 25 50 75 100

[0094] Downlink control information is transmitted within the first N OFDM symbols in a subframe. Typically, N = {1, 2, 3}. Therefore, N varies in each subframe depending on the amount of control information to be transmitted in the current subframe. The control information includes: a control channel transmission interval indicator, which indicates how many OFDM symbols are used to transmit control information; scheduling information for downlink or uplink data; and HARQ ACK / NACK signals.

[0095] In the LTE system, scheduling information for downlink data or uplink data is sent from the base station to the UE via downlink control information (DCI). DCI is defined in various formats. Depending on whether the DCI is scheduling information for uplink data (UL grant) or scheduling information for downlink data (DL grant), whether the DCI is a compact DCI with small-size control information, whether the DCI applies spatial multiplexing using multiple antennas, and whether the DCI is a DCI for power control, the determined DCI format is applied and operated. For example, DCI format 1 corresponding to scheduling control information (DL grant) on downlink data can be configured to include at least the following control information.

[0096] - Resource Allocation Type 0 / 1 Flag: This flag indicates whether the resource allocation type is Type 0 or Type 1. Type 0 applies a bitmap scheme and allocates resources in units of resource block groups (RBGs). In the LTE system, the basic scheduling unit is a resource block (RB), which is represented by time and frequency region resources. An RBG includes multiple RBs and is the basic scheduling unit in the Type 0 scheme. Type 1 allows for the allocation of predetermined RBs within an RBG.

[0097] - Resource Block Assignment: Notifies the RBs allocated for data transmission. The indicated resources are determined by the system bandwidth and resource allocation type.

[0098] - Modulation and Coding Scheme (MCS): indicates a modulation scheme used for data transmission and the size of a transport block (TB) as data to be transmitted.

[0099] -HARQ process number: Notifies the HARQ process number.

[0100] - New data indicator: indicates whether data is transmitted through HARQ initial transmission or through retransmission.

[0101] - Redundancy version: indicates the redundancy version of HARQ.

[0102] - Transmit Power Control (TPC) Command for Physical Uplink Control Channel (PUCCH): indicates a transmit power control command for PUCCH, which is an uplink control channel.

[0103] Through channel coding and modulation processing, DCI is transmitted through the physical downlink control channel (PDCCH) or enhanced PDCCH (EPDCCH). In the following, PDCCH or EPDCCH transmission can be interchanged with DCI transmission performed through PDCCH or EPDCCH. This description can also be applied to other channels.

[0104] Typically, for each UE, the DCI is scrambled using a specific radio network temporary identifier (RNTI) (or UE identifier), cyclic redundancy check (CRC) bits are added to it, and then channel coding is performed to configure and transmit each independent PDCCH. In the time domain, the PDCCH is mapped and transmitted during the control channel transmission interval. The mapping position of the PDCCH in the frequency domain is determined by the identifier (ID) of each UE and is distributed to the entire system transmission band.

[0105] Downlink data is sent via the Physical Downlink Shared Channel (PDSCH), which is a physical channel used to transmit downlink data. The PDSCH is transmitted after the control channel transmission interval. Scheduling information such as the modulation scheme, specific mapping position in the frequency domain, etc. can be reported through the DCI sent via the PDCCH.

[0106] The base station can report the modulation scheme applied to the PDSCH to be transmitted to the UE and the size of the data to be transmitted (transport block size (TBS)) through the 5-bit MCS formed in the control information included in the DCI. The TBS corresponds to the size of the data (TB) to be transmitted by the base station before channel coding for error correction is applied.

[0107] The modulation schemes supported by the LTE system include Quadrature Phase Shift Keying (QPSK), 16-QAM (16QAM), and 64QAM, and their modulation orders (Qm) correspond to 2, 4, and 6, respectively. That is, in the case of QPSK modulation, 2 bits can be transmitted per symbol. In the case of 16QAM modulation, 4 bits can be transmitted per symbol. In the case of 64QAM modulation, 6 bits can be transmitted per symbol.

[0108] Figure 2 The basic structure of a time-frequency region according to the prior art is shown, where the time-frequency region is a radio resource region in which data or a control channel is transmitted in an uplink of an LTE system.

[0109] refer to Figure 2 , the horizontal axis indicates the time region and the vertical axis indicates the frequency region. The minimum transmission unit in the time region is the SC-FDM symbol 202, and one time slot 206 consists of N symb SC-FDMA symbols. One subframe 205 consists of two time slots. The minimum transmission unit in the frequency domain is a subcarrier, and the entire system transmission band (transmission bandwidth) 204 consists of a total of N BW Subcarriers. BW Has a value proportional to the system transmission band.

[0110] The basic unit of resources in the time-frequency domain is a resource element (RE) 212 and can be defined by an SC-FDMA symbol index and a subcarrier index. A resource block (RB) 208 consists of N symb N consecutive SC-FDMA symbols and frequency regions BW Therefore, RB is defined by N consecutive subcarriers. symb ×N RBThe PUCCH is mapped to a frequency region corresponding to one RB and can be transmitted during one subframe.

[0111] In the LTE system, a timing relationship is defined between the PDSCH, which is a physical channel for transmitting downlink data, or the PDCCH or EPDCCH including a semi-persistent scheduling release (or SPS release), and the PUCCH or PUSCH, which is an uplink physical channel for transmitting HARQ ACK / NACK. For example, in an LTE system operating in FDD mode, an HARQ ACK / NACK corresponding to the PDSCH or the PDCCH or EPDCCH including an SRS release transmitted in the n-4th subframe is transmitted via the PUCCH or PUSCH in the nth subframe.

[0112] In the LTE system, downlink HARQ utilizes an asynchronous HARQ scheme in which the data retransmission timing is not fixed. Specifically, when a base station receives HARQ NACK feedback from a UE regarding initially transmitted data sent by the base station, the base station freely determines the timing for retransmitting the data through scheduling operations. For HARQ operations, the UE buffers data determined to be erroneous as a result of decoding received data and combines this data with subsequently retransmitted data.

[0113] When the UE receives the PDSCH including downlink data transmitted from the base station in subframe n, the UE transmits uplink control information including HARQ ACK or NACK for the downlink data to the base station via the PUCCH or PUSCH in subframe n+k. In this case, k is defined differently depending on the FDD or time division duplex (TDD) of the LTE system and the subframe configuration. For example, in the case of an FDD LTE system, k is fixed to 4. Meanwhile, in the case of a TDD LTE system, k can be changed according to the subframe configuration and subframe number.

[0114] In the LTE system, unlike downlink HARQ, uplink HARQ utilizes a synchronous HARQ scheme, in which the data transmission timing is fixed. Specifically, the uplink / downlink timing relationship between the Physical Uplink Shared Channel (PUSCH), a physical channel for uplink data transmission, the PDCCH, a preceding downlink control channel, and the Physical Hybrid Indicator Channel (PHICH), a physical channel for transmitting downlink HARQ ACK / NACK messages corresponding to uplink data on the PUSCH, is fixed by the following rules.

[0115] When a UE receives a PDCCH containing uplink scheduling control information transmitted from a base station or a PHICH for transmitting downlink HARQ ACK / NACK in subframe n, the UE transmits uplink data corresponding to the control information via the PUSCH in subframe n+k. In this case, k is defined differently depending on whether the LTE system is FDD or TDD and its configuration. For example, in an FDD LTE system, k is fixed to 4. In a TDD LTE system, k can be changed according to the subframe configuration and subframe number.

[0116] Furthermore, when a UE receives a PHICH for transmitting a downlink HARQ ACK / NACK from a base station in subframe i, the PHICH corresponds to the PUSCH transmitted by the UE in subframe ik. In this case, k is defined differently depending on whether the LTE system is FDD or TDD and its configuration. For example, in an FDD LTE system, k is fixed to 4. Meanwhile, in a TDD LTE system, k may vary depending on the subframe configuration and subframe number.

[0117] The description of the wireless communication system has been made based on the LTE system, but the present disclosure is not limited to the LTE system and can be applied to various wireless communication systems such as NR and 5G.

[0118] Figure 3 and Figure 4 An example of allocating data for enhanced mobile broadband (eMBB), ultra-reliable and low-latency communication (URLLC), and massive machine type communication (mMTC), which are considered services in 5G or NR systems, to frequency-time resources is shown.

[0119] exist Figure 3In the example, eMBB, URLLC, and mMTC data are allocated to the entire system frequency band 300. When URLLC data 303, 305, and 307 are generated while eMBB data 301 and mMTC data 309 are allocated to and transmitted in a specific frequency band and therefore need to be transmitted, the transmitter can clear the portion to which eMBB data 301 and mMTC data 309 have been allocated and transmit URLLC data 303, 305, and 307. Short latency is particularly important for URLLC services, so URLLC data 303, 305, and 307 can be transmitted while being allocated to the portion of resources 301 to which eMBB is allocated. However, when URLLC is additionally allocated and transmitted in resources allocated to eMBB, eMBB data may not be transmitted in the duplicate frequency-time resources, potentially degrading eMBB data transmission performance. In other words, in this case, eMBB data transmission may fail due to the URLLC allocation.

[0120] exist Figure 4 In the UE, the entire system frequency band 400 can be divided into subbands 402, 404, and 406 and used to transmit services and data. The subbands can be pre-divided and their information can be sent to the UE through higher signaling, or the base station can randomly divide the subbands and provide services to the UE without any information about the subbands. Figure 4 An example is shown in which subband 402 is used for eMBB data transmission 408, subband 404 is used for URLLC data transmission 410, 412, and 414, and subband 406 is used for mMTC data transmission 416. Figure 3 and Figure 4 In the example, the length of the transmission time interval (TTI) used for URLLC transmission can be shorter than the length of the TTI used for eMBB or mMTC transmission.

[0121] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description of the present disclosure, when a detailed description of a known function or configuration incorporated herein may make the subject matter of the present disclosure unclear, its detailed description will be omitted. The terms described below are defined in consideration of the functions in the present disclosure and may vary depending on the user, the user's intention or custom. Therefore, the definition of terms should be based on the content of the entire specification.

[0122] In the following, a base station is an entity that allocates resources to a UE, and may be at least one of an eNode B, a node B, a base station (BS), a radio access unit, a base station controller, and a node on a network. A UE may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, and a multimedia system capable of performing a communication function. In the following, embodiments of the present disclosure are described based on an LTE or LTE-A system by way of example, but embodiments of the present disclosure may be applied to other communication systems having similar technical backgrounds or channel forms. For example, 5th generation mobile communication technology (5G, New Radio (NR)) developed after LTE-A may be included therein. In addition, embodiments of the present disclosure may be modified without departing from the scope of the present disclosure, and may be applied to other communication systems as determined by those skilled in the art.

[0123] In particular, the terms "physical channel" and "signal" in conventional LTE or LTE-A systems may be used to describe the methods and apparatuses proposed in the present disclosure. However, embodiments of the present disclosure may be applied to wireless communication systems other than LTE and LTE-A systems.

[0124] Furthermore, embodiments of the present disclosure may be applied to FDD and TDD systems.

[0125] Hereinafter, in the present disclosure, physical layer signaling is a method of sending a signal from a base station to a UE through a downlink control channel of a physical layer or from a UE to a base station through an uplink control channel of a physical layer, and may be referred to as L1 signaling or PHY signaling.

[0126] In the present disclosure, higher signaling or high-layer signaling is a method of sending a signal from a base station to a UE through a downlink data channel of a physical layer or sending a signal from a UE to a base station through an uplink data channel of a physical layer, and may be referred to as RRC signaling, L2 signaling, PDCP signaling, or MAC control element (MAC CE).

[0127] In the present disclosure, TPMI indicates a transmission precoding matrix indicator or transmission precoding matrix information, and similarly, TPMI may be expressed as beamforming vector information or beam direction information.

[0128] In the present disclosure, uplink (UL) DCI or UL-related DCI is physical layer control signaling (L1 control), which includes information required for uplink transmission, such as uplink resource configuration information and resource configuration type information (such as UL grant), uplink power control information, cyclic shift of uplink reference signal, orthogonal cover code (OCC), channel state information (CSI) request, sounding reference signal (SRS) request, MCS information for each codeword, and uplink precoding information field.

[0129] In wireless communication systems such as LTE and LTE-A, discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-SOFDM) is used to reduce PAPR and improve coverage in uplink transmissions. Furthermore, due to the supported frequency band characteristics and hardware development procedures, LTE and LTE-A systems only consider a small number of UE transmit antennas. Therefore, due to this characteristic, diversity-based transmission is not supported.

[0130] However, unlike current wireless communication systems that assume a maximum of four UE transmission antennas, in NR systems, due to improvements in antenna form factors and the development of RF technology using high-frequency carriers, it is very likely that the UE will use four or more transmission antennas. Conventional DFT-S OFDM is only used for rank 1 transmission, and supports transmission using CP-OFDM in rank 2 or higher transmissions. Therefore, in NR wireless communication systems, the demand for diversity transmission in the uplink increases. Therefore, the present disclosure proposes a method for transmitting a signal in the uplink using a diversity scheme and a method for indicating a diversity scheme.

[0131] Hereinafter, it is assumed that dynamic beamforming or semi-dynamic beamforming is supported to perform uplink transmission in various scenarios in the present disclosure.

[0132] Figure 5 An example of uplink transmission with dynamic beamforming or semi-dynamic beamforming is shown.

[0133] Dynamic beamforming is suitable for situations where the UE's mobility is low, the spacing between cells is good, or accurate uplink channel information is available, such as when inter-cell interference management is good. In this case, UE 702 can perform uplink transmissions using a beam with a narrow beamwidth based on accurate uplink channel direction information. Base station 701 notifies the UE of the TPMI via a UL DCI, such as a UL grant. After receiving the TPMI signaling, the UE transmits uplink data to the base station using the precoder or beamforming vector (or matrix) indicated by the TPMI.

[0134] Multiple-input multiple-output (MIMO) transmission based on a codebook for supporting dynamic beamforming can be operated by including a UL DCI field for precoding information (precoding matrix indicator (PMI)) (determined according to the rank indicator (RI) when the corresponding RI exists). In this case, the precoding information field indicates the precoding matrix used for uplink transmission allocated to the corresponding UE. In the case of wideband precoding information, the precoding matrix can be specified to indicate one direction in the entire allocated frequency band; in the case of subband precoding information, the precoding matrix can be specified to indicate one direction for each subband. In this case, the precoding vector specified by the subband precoding information can be included in the precoding vector group specified by the wideband precoding information. Therefore, the signaling burden of the subband precoding information can be reduced.

[0135] Semi-dynamic beamforming is suitable for situations where the UE's mobility is high, the spacing between cells is poor, or the uplink channel information is incorrect, such as when inter-cell interference management is poor. In this case, UE 703 can perform uplink transmission using a beam group including beams in various directions based on the exemplary uplink channel direction information. Base station 701 notifies the UE of the TPMI via a UL DCI such as a UL grant. After receiving the TPMI signaling, the UE transmits uplink data to the base station using a subset of the precoder or beamforming vector (or matrix) indicated by the TPMI.

[0136] MIMO transmission based on a codebook for supporting semi-dynamic beamforming can be operated by including a UL DCI with a precoding information (PMI) field (determined based on the RI when the corresponding RI exists). In this case, the precoding information field indicates the group of precoding vectors used for uplink transmission assigned to the corresponding UE. Information about the group of precoding vectors is wideband information and can be used equally across the entire uplink frequency band. The UE can apply a precoder cycle according to a predetermined pattern to the beams included in the notified precoding vector group, and precoder cycling can be supported by diversity-based transmission to the UE.

[0137] Figure 6 An example is shown in which a UE and a base station transmit reference signals in order to acquire channel state information required for uplink transmission in an NR system.

[0138] The transmission of reference signals supported by the NR system can use CSI-RS beams on a cell basis (the cell is a wide area for supporting multiple antennas) or on a sector basis, and may vary depending on whether the non-precoded CSI-RS (NP CSI-RS) 610 is used to perform beamforming using the UE's precoding feedback, or the beamformed CSI-RS (BF CSI-RS) 630 is used to reduce CSI-RS overhead by applying beamforming to the antenna. In the case of the corresponding NP CSI-RS, multiple unit resource configurations can be used to support many antenna ports; in the case of BF CSI-RS, multiple CSI-RS sources can be configured instead of unit resource configurations, and the UE can select one or more resources from them and report channel state information.

[0139] Similarly, when a UE transmits an SRS, the following may be applied: NP SRS 620, which supports multiple antennas within a single SRS resource, and BF SRS 640, which utilizes information regarding one or more SRS resources configured in the UE. The base station can transmit the SRS using the SRS resources configured by the base station, receive the corresponding SRS, indicate the optimal transmission beam required between the UE and the base station to the UE, and discover the optimal receive beam for the base station. Furthermore, if channel reciprocity or beam determination between the uplink and downlink matches, the NP CSI-RS 610 and BF CSI-RS 630 may be used to select an uplink beam.

[0140] The precoding vector group or beam group in the uplink can be defined by the following two methods.

[0141] The first method is a method of defining a beam group based on hierarchical PMI. For example, a PMI indicating one code point may include two or more sub-PMIs. If it is assumed that a PMI is composed of two sub-PMIs, it is possible to specify that the first PMI is one of the beam group indices including a specific number of precoding vectors, and the second PMI is one of the indices of the precoding vectors included in the beam group. For example, the beam group G including the PMI may be defined as follows [Equation 1]: i Uplink codebook, beam group G i Including M UE transmission antennas and B DFT precoding vectors v based on an oversampling factor of 0 k .

[0142] [Equation 1]

[0143]

[0144] G i =[v Ai v mod(Ai+1，OM) … v mod(Ai+B-2，OM)v mod(Ai+B-1，OM) ]

[0145] A is the beam skip factor and represents the interval between beam groups (beam unit). In this example, the first PMIi is the index of the beam group, and a single precoding vector can be obtained by having Specifies the second PMI of the payload.

[0146] The second method is to define a beam or beam group based on a single structure PMI. For example, one PMI can be understood as an indicator indicating a single beam or beam group according to high-layer or physical layer signaling. For example, the uplink codebook including the beam group Gi can be defined as follows [Equation 2], where the beam group G i Including M UE transmission antennas, the i-th DFT precoding vector v based on the oversampling factor of 0 i and B DFT precoding vectors.

[0147] [Equation 2]

[0148]

[0149] G i =[v i v mod(i+1，OM) … v mod(i+B-2，OM) v mod(i+B-1，OM )]

[0150] In this example, when the higher layer or physical layer signaling indicates dynamic beamforming or wideband precoding, the i-th PMI can be understood as indicating v i On the other hand, when the higher layer or physical layer signaling indicates semi-dynamic beamforming or subband precoding, the i-th PMI can be understood as indicating G i [Table 2] shows an example of a TPMI analysis method when dynamic or semi-dynamic beamforming transmission or wideband or subband precoding is specified by higher layer signaling. [Table 3] shows an example of a TPMI analysis method when dynamic or semi-dynamic beamforming transmission or wideband or subband precoding is specified by physical layer signaling.

[0151] [Table 2]

[0152]

[0153] [Table 3]

[0154]

[0155] In [Equation 1] and [Equation 2], it is assumed that the UE transmit antenna has a one-dimensional antenna array and therefore the codebook includes a one-dimensional DFT vector, but if the UE transmit antenna has a two-dimensional antenna array, another type of uplink codebook may be used. For example, if the UE transmit antenna array includes M1 antenna ports in the first dimension and M2 antenna ports in the second dimension, the precoding vector may be defined as shown in [Equation 3] by a pair of indices (m1, m2). and beam groups

[0156] [Equation 3]

[0157]

[0158]

[0159]

[0160] Assume that in [Equation 1], [Equation 2], and [Equation 3], the UE transmit antennas have the same polarization. However, if the UE transmit antennas have a dual-polarization array, the example of the uplink codebook can be changed in consideration of this. For example, if the UE transmit antennas have a one-dimensional array including M antenna ports for each polarization, i.e., a total of 2M antenna ports, the rank 1 precoding vector v can be defined as shown in the following [Equation 4] i，k and beam group G m .

[0161] [Equation 4]

[0162]

[0163]

[0164] G m =[v m v mod(m+1，OM) … v mod(m+B-2，OM) v mod(n+B-1，OM) ],m=(K-1)i+k

[0165] In [Equation 4], K represents the in-phase quantization level.

[0166] In another example, if the UE transmit antenna has a two-dimensional array including M1M2 antenna ports for each polarization, that is, a total of 2M1M2 antenna ports, the rank 1 precoding vector can be defined as shown in the following [Equation 5] M1 and M2 are the number of UE transmit antenna ports for each polarization included in the first and second dimensions. In the case of beam groups, it can be based on [Equation 5] A configuration similar to [Equation 3] is performed.

[0167] [Equation 5]

[0168]

[0169]

[0170]

[0171] It is obvious that the dynamic / semi-dynamic beamforming or wideband / subband precoding signaling examples, ie, [Table 2] and [Table 3] can be easily applied to the codebook examples.

[0172] The examples have been described based on a rank 1 codebook indicating a single direction, but the principle is not limited thereto in actual implementation and can be equally applied to a rank 2 or higher codebook indicating two or more directions.

[0173] These examples assume a case where UL DCI includes one TPMI, and a UE receiving the TPMI may apply uplink precoding for one beam direction or one beam group to the entire uplink frequency band.

[0174] Figure 7 An example of allocating resources for uplink transmission and applying subband precoding is shown. For example, a base station may transmit a UL DCI including information for multiple subbands, such as N subbands, through UL DCI for subband precoding. PMI N of the precoding information of the subband PMI TPMI. N PMI The value of RA is determined by the number of uplink resources (RBs) allocated to the UE. RB , the number of RBs included in the subband P SUBBAND and uplink resource allocation method.

[0175] Reference numeral 710 indicates uplink resources when consecutive RBs are allocated, and reference numeral 720 indicates uplink resources when clustered RBs are allocated. Figure 7 In the example, assume that P SUBBAND = 4. If resources are allocated as indicated by reference numeral 710, that is, if resources configured as one cluster are allocated, then it is possible to allocate resources based on RA RB and P SUBBAND The number of necessary subbands is calculated by [Equation 6]. A cluster is a set of uplink RBs that are consecutively allocated.

[0176] [Equation 6]

[0177]

[0178] However, if resources configured as one or more clusters are allocated as indicated by reference numeral 720, the calculation of [Equation 6] may not be accurate. In this case, N may be calculated based on the method of [Equation 7] or [Equation 8]. PMI [Equation 7] is for the lowest index RB among the allocated RBs based on low and the highest index RB high To calculate N PMI [Equation 8] is a method for calculating N based on the number of consecutive RBs allocated to each cluster. PMI In [Equation 8], RA RB,n represents the number of consecutive RBs allocated to the n-th cluster, and N represents the number of clusters allocated to the UE.

[0179] [Equation 7]

[0180]

[0181] [Equation 8]

[0182]

[0183] If an uplink PMI contains T bits, then in this example, N bits may need to be transmitted for uplink subband precoding. PMI The TPMI payload is T bits. This means that when using several subbands and a codebook with several bits, TPMI signaling may require scores of bits or more. Transmitting UL DCI may be burdensome, and therefore, it may be necessary to define a new method for performing UL subband precoding to reduce the UL DCI burden. If an environment supporting subband precoding is defined in uplink transmission, UL DCI coverage can be improved for UEs with a small number of transmit and receive antennas, and uplink transmission performance and overall system performance of UEs can be improved by supporting subband precoding for UEs with a large number of transmit and receive antennas.

[0184] <Example 1-1>

[0185] The UE may transmit an uplink signal by applying different precoding using a plurality of demodulation reference signals (DMRSs) for each RE on the frequency axis in order to perform uplink diversity-based transmission. Figure 8 It shows that, assuming that two DMRS ports are used, different precoding methods proposed in this embodiment are applied to REs.

[0186] exist Figure 8In this method, the UE can apply different precodings to REs through two DMRS ports within one RB. In this case, the base station can allocate and indicate multiple DMRSs for transmission to the UE, and the UE receiving it can send data through the multiple DMRS ports. This method can provide a larger amount of diversity gain even when resources are allocated to the UE in a small number of RBs, and additional diversity gain can be expected by adding and using precoder cycles at the physical resource block (PRB) or precoding resource block group (PRG) level.

[0187] Since the RE-level precoder cycle uses different precoders depending on the frequency, it may not be used for uplink data transmission using discrete Fourier transform spread OFDM (DFT-S OFDM) and is effective in the case of cyclic prefix OFDM (CP-OFDM). In addition, in order to increase the diversity gain, different precoders can be applied to symbols, such as Figure 9 shown.

[0188] Figure 9 An example is shown in which a precoder is applied to different RE-specific mappings for each symbol to increase diversity gain. Figure 10 Shown Figure 8 The performance of the precoder loop method 1010 and Figure 9 The performance comparison between the precoder loop method 1020 is shown. Figure 10 As shown, in Figure 9 In the method, the UE should apply a more complex precoder mapping, but the performance may be better than Figure 8 method has better results.

[0189] <Example 1-2>

[0190] The UE may perform uplink diversity-based transmission by transmitting an uplink signal using a plurality of DMRS ports and applying different precoding for each time unit resource. Figure 11A and Figure 11B An example of applying different precoding to the time resource unit proposed by this embodiment based on the assumption that the number of DMRS ports is the same as the number of transmitted ranks is shown.

[0191] It is assumed that the UE cycles the precoder for each slot or mini-slot as indicated by reference numerals 1110 and 1120. For example, as indicated by reference numeral 1110, the first slot is transmitted using DMRS port 0, and the second slot is transmitted using DMRS port 1. This is a method of supporting diversity transmission based on precoder cycling, which uses a DMRS port transmitted for each slot or mini-slot based on a DMRS structure in which some REs of one symbol are used for one DMRS port.

[0192] The advantage of the precoder cycling method is that it can support diversity transmission for the UE without any increase in the overhead of the DMRS port. The UE can estimate the channel of the corresponding unit resource through the channel of the DMRS port of the unit resource allocated to the corresponding precoder.

[0193] Reference numerals 1130 and 1140 indicate a method of cycling two or four precoders per OFDM symbol based on a DRMS ​​structure in which some REs per symbol are used for one DMRS port. The methods indicated by reference numerals 1130 and 1140 can have a shorter precoder cycling unit and thus can achieve higher diversity compared to the method indicated by reference numerals 1110 or 1120.

[0194] <Examples 1-3>

[0195] Figure 12 An example of a precoder cycle in time units based on the assumption that a DMRS is transmitted in one complete symbol is shown.

[0196] exist Figure 12 In this embodiment, the Zadoff-Chu sequence is assumed to be used for DMRS, but various sequences such as pseudo-noise (PN), gold sequence, or CDM can be supported. The non-orthogonal DMRS multiplexing method based on ZC can support a relatively large number of DMRS ports within a symbol. Therefore, as indicated by reference numeral 1210, multiple DMRS ports can be used within a single RB to apply different precoding to each OFDM symbol. Reference numerals 1220 and 1230 indicate examples in which different precoding is applied to OFDM symbols using multiple DMRS ports. In this case, the base station can allocate and indicate multiple DMRSs for transmission to the UE, and the UE receiving the precoding can send data via the multiple DMRS ports. Even when resources are allocated to the UE in a smaller number of RBs, this method can provide greater diversity gain through time unit precoding cycles, and additional diversity gain can be expected by adding and using precoder cycles at the PRB or PRG level. In addition, this method uses the same precoder in each time unit and can therefore be applied to uplink data transmission using DFT-S OFDM.

[0197] <Examples 1-4>

[0198] The UE may transmit an uplink signal by applying different precoding using a plurality of DMRS ports for each RB or PRG in order to perform uplink diversity-based transmission. Figure 13An example of applying different precoding to the RB or PRG proposed in this embodiment based on the assumption that two DMRS ports are used is shown.

[0199] exist Figure 13 In the case of DMRS, the UE can apply different precodings to REs by the number of DMRS ports, which is the same as the number of ranks transmitted by the UE for each RB or PRG. In this case, the base station can allocate and indicate the DMRS for transmission to the UE, and the UE that receives it can transmit data through the DMRS port. Since the precoder cycle at the RB or PRG level uses a different precoder for each frequency, the precoder cycle may not be used for uplink data transmission using DFT-S OFDM and is effective when CP-OFDM is used.

[0200] <Examples 1-5>

[0201] The base station may send the following information to the UE for uplink transmission.

[0202] • Carrier indicator - indicates which carrier is used for the corresponding uplink transmission.

[0203] • Frequency Hopping Indicator – Indicates whether frequency hopping is performed.

[0204] RB Allocation and Hopping Resource Allocation - Allocates RBs and hopping resources for uplink transmission of the UE. Analysis of the field may vary depending on whether the UE receives information indicating that hopping is to be performed from the frequency hopping indicator.

[0205] • MCS and RV - Indicates the RV required for demodulation, channel coding, and HRQ operations to be used for uplink transmissions of the UE.

[0206] ● New data indicator - indicates whether the corresponding data is new data.

[0207] ● DMRS indicator – indicates the DMRS port required for corresponding data transmission. If OCC-based orthogonal multiplexing is supported, necessary OCC information may also be sent, and in the case of ZC sequence-based transmission, cyclic shift information required by the ZC sequence may also be sent.

[0208] ●CSI request indicator – triggered when aperiodic channel state information is required

[0209] • SRS request indicator – triggered when aperiodic SRS transmission is required.

[0210] • Resource Allocation Type – indicates the resource allocation type required for uplink transmission.

[0211] • Transmission Rank Indicator (TRI) – Indicates the rank information required for uplink transmission.

[0212] ● Transmitted Precoding Matrix Indicator (TPMI) - indicates the PMI information required for uplink transmission. At this time, only wideband TPMI can be sent to reduce DCI overhead, and if possible, both wideband TPMI and subband TPMI can be sent.

[0213] The base station can indicate diversity transmission to the UE based on this information, and when the UE receives this indication, the UE can receive an indication of diversity transmission from the base station via TRI information. For example, a precoder cycle is applied to a specific rank, and if another rank is indicated, the precoder cycle is not applied. [Table 4] shows such an embodiment.

[0214] [Table 4]

[0215]

[0216] like Figure 4 As shown in Example 1 of , if the base station indicates rank 1 transmission to the UE, the UE may support neither precoder cycling nor diversity-based transmission. If rank 2 or higher transmission is indicated, the UE applies precoder cycling or diversity-based transmission. As shown in Example 2, the UE does not support diversity-based transmission in rank 2 or lower transmission. Only when rank 3 or higher transmission is indicated, the UE may apply precoder cycling or diversity-based transmission, or may apply different transmissions to ranks other than ranks 2 and 3. Therefore, the base station can indicate diversity-based transmission without any additional DCI bits or DCI formats for diversity-based transmission.

[0217] In this case, the existing codebook can be used for diversity-based transmission. Figure 14A An example of using a codebook for diversity-based transmission is shown.

[0218] exist Figure 14A In this example, it is assumed that the UE receives an allocation with a TRI of 3 and a TPMI of 0, and that a precoder cycle is applied to each RB described in Examples 1-4. In this case, the precoding indicated by the TPMI can be applied to the cycle unit used for the cycle. That is, precoder 1400 for layer 0 can be applied to RB#0, precoder 1410 for layer 1 can be applied to RB#1, and precoder 1420 for layer 2 can be applied to RB#2. Although the description is based only on <Example 1-4>, the description can be applied to all of <Example 1-1> to <Example 1-4> and other diversity-based transmission methods.

[0219] Although TRI is indicated together with TPMI, it can be indicated separately from TPMI. [Table 6] shows a method of indicating TRI and TPMI together.

[0220] [Table 6]

[0221]

[0222] In this case, the field used for indication may be referred to as an indicator of precoding information and the number of layers.

[0223] The configuration can be indicated using the RRC or DCI field, which indicates whether this method is used. If RRC is not configured, it is regarded as non-diversity transmission, and therefore all layers can be sent together in the same resource. If RRC is configured, the layer can be cycled for each resource as described above. In the case of using the indication of the DCI field, when the DCI is 0, the corresponding TRI and TPMI information are sent based on transmission other than diversity transmission; and when the DCI is 1, the corresponding TRI and TPMI information are sent based on diversity transmission. At this time, the rank used for diversity transmission can be fixed to a lower rank that is different from the actually indicated rank, for example, rank 1 or rank 2. For this purpose, it is possible to support it using another table.

[0224] An advantage of this embodiment is that the number of precoders required for the precoder cycle can be dynamically controlled. For example, if rank 3 transmission and rank 4 transmission are configured, and all transmissions can use rank 1 transmission based on diversity, then when three precoder cycle-based transmissions are expected, the base station can indicate rank 3, and when four precoder cycle-based transmissions are expected, the base station can indicate rank 4, and the UE can decode the downlink data based on the precoder cycle based on the indication of the base station.

[0225] In addition, each rank indication may also support diversity-based transmission of other ranks. For example, rank 3 may support diversity-based transmission of rank 1, while rank 4 may support diversity-based transmission of rank 2.

[0226] <Examples 1-6>

[0227] In order to allow the base station to send uplink diversity transmission to the UE and allow the UE to receive such an indication, the UE may receive in advance an indication of a plurality of SRS resources among the SRS resources configured through RRC from the base station.

[0228] In the NR system, the base station can detect the channel state in the beam direction in which the UE performs transmission through the SRS sent by the UE, and indicate the SRS resources to the UE again so that the UE can identify the beam direction required for uplink data transmission. In addition, the UE can identify how many antenna ports of the codebook are used for the UE's transmission through the indicated SRS resources, and how to configure the codebook subset constraints of the corresponding codebook.

[0229] At this point, you can configure the SRS details required for SRS transmission. You can also configure the SRS transmission frequency band, transmission period, and slot (or subframe or mini-slot) offset. In addition, you can also send the number of antenna ports or the cyclic shift and transmission comb used for ZC sequence transmission for each SRS group.

[0230] In order to effectively use SRS resources for indication, some of the SRS resources configured by the higher layer (such as RRC) can be pre-activated, and then only some of the activated resources can be indicated by DCI. Specifically, in the case of high frequency bands, due to the reduction in form factor, the data beam width of the UE becomes narrower, and accordingly, it may be necessary to support a large number of beams and a corresponding number of SRS resources. At this time, it is possible to optimize the resources suitable for the UE position and the optimal beam group by activating and deactivating SRS resources. The method of actually transmitting SRS can be described below.

[0231] SRS resource configuration and triggering method 1: pre-configure multiple non-periodic SRS resources, activate some of the configured resources, and trigger some of the activated resources.

[0232] SRS resource configuration and triggering method 2: pre-configure multiple non-periodic SRS resources, and periodically send corresponding CSI-RS resources according to activation until deactivation.

[0233] SRS resource configuration and triggering method 1 pre-configures multiple aperiodic SRS resources, activates some of the configured resources, and triggers activation of some of the resources. To activate the resources, the base station may signal an activation signal via a MAC control element (CE). Upon receiving a DCI trigger for corresponding SRS resource transmission from the base station, the UE receiving the activation signal may transmit the corresponding SRS.

[0234] SRS resource configuration and triggering method 2 pre-configures multiple semi-persistent SRS resources and periodically transmits the corresponding SRS resources based on activation until deactivation. To activate the resources, the base station can signal an activation signal via a MAC CE. Furthermore, the base station can activate or deactivate candidate resources via a MAC CE signal, and can actually perform the activation or deactivation via a MAC CE signal or some DCI in the activated candidate resources.

[0235] Figure 14B An example of an operation for activating SRS candidate resources through MAC CE and actually activating SRS candidate resources through DCI is shown. Figure 14B , in step 1430, the base station activates the reporting candidate resources through a MAC CE. In order to receive and then activate the signal, in step 1440, the UE requires time X, and then in step 1450, the UE receives a DCI for activating the reporting resource from the base station. Thereafter, in step 1460, the UE receives a DCI for deactivating the reporting resource, and in step 1470, receives a MAC CE for deactivating the reporting candidate resource. In order to receive and then deactivate the signal, in step 1480, the UE requires time Y. For diversity transmission in <Example 1-1> to <Example 1-4> based on SRS candidate resources, the UE may receive an indication of multiple SRS resources or SRS sets. In addition, in order to identify a beam for a precoder cycle in <Example 1-1> to <Example 1-4>, multiple SRS resources may be applied to each cycle unit. For example, precoding applied to UL DMRS 0 may be sent based on the first indicated SRS resource to support Figure 8 The precoder shown is cycled, and the precoding applied to UL DMRS1 can be transmitted based on the second indicated SRS resource. This application can be performed equally on other embodiments, and different numbers of SRS resources or SRS sets can be indicated based on the number of cycled precoders. In addition, multiple SRS resources can be applied together with subband precoding.

[0236] Figure 15 The time and frequency resources used by multiple UEs to transmit uplink data are shown.

[0237] like Figure 15 (a) to Figure 15As shown in (c) in FIG, the uplink transmission allocation varies depending on the channel state of the UE. Specifically, due to the characteristics of the battery of the UE and the hardware limitations, the transmission power in the uplink is limited. Therefore, it is necessary to consider resource allocation characteristics that are different from those of the downlink. As indicated by reference numeral 1510, a UE with a good channel state can use a wide band and a short time to send uplink data. This is because since the channel state between the UE and the base station is good, sufficient data can be sent using only the transmission power of the UE. As indicated by reference numeral 1520, the UE uses a slightly limited frequency band and an increased time to send data. This is because the UE has a relatively poor channel state compared to the UE indicated by reference numeral 1510. In the uplink, the power spectral density of the frequency can be increased by reducing the transmission band and increasing the transmission time, as shown in FIG. Figure 15 As shown. Furthermore, although the UE's transmission power is limited to a specific time, by repeatedly using the same power, the actual coverage of the UE's data transmission can be improved. Furthermore, if the channel between the UE and the base station is very poor, resources can be allocated to transmit signals for a long period of time in a very narrow frequency band, as indicated by reference numeral 1530.

[0238] like Figure 15 As shown in , the characteristics of uplink transmission vary depending on each UE, and therefore, the precoding-related information required when the UE performs transmission may also vary depending on each frequency band. Therefore, if the UE supports whole-band precoding, the base station indicates one SRS, and the base station indicates the number of SRS resources or SRS resource sets that are equal to or less than the number of subbands or the number of bandwidth parts corresponding to the set of subbands, thereby supporting the uplink transmission of the UE. In addition, the UE can identify how many antenna ports of the codebook are used for the UE's transmission through the indicated SRS resources, and how to configure the codebook subset constraint of the corresponding codebook.

[0239] Multiple identical SRS resources or SRS set indication fields can be used to indicate multiple SRS resources or SRS sets from the base station to the UE. Whether the indicated SRS resource or SRS set is used for subband precoding or diversity-based transmission is provided based on the DCI field, MAC CE or RRC field. For example, if the DCI field is 0, the corresponding SRS set can be used for subband precoding; and if the DCI field is 1, the corresponding SRS set can be used for diversity-based transmission. In addition, whether to perform subband precoding-based transmission or diversity-based transmission is configured through RRC or MAC CE, and the corresponding SRS resource can be used for configuration purposes according to the configuration result. That is, it can be understood that the beam circulates on the frequency axis (in the case of subband precoding) and the time axis (in the case of diversity).

[0240] At this time, for transmission, the subband precoding or the second precoding per each SRS resource can be sent through MAC CE or RRC. Therefore, it is possible to reduce DCI overhead and receive precoding information.

[0241] Furthermore, the number of configured SRS antenna ports is the same for all, or only one of the multiple antenna ports may be configured. Unlike base stations that support a relatively large number of antennas (e.g., 16 or 32 ports), UEs have a relatively small number of antennas due to their form factors. Therefore, there may be little need to configure the corresponding multiple antennas differently, and complexity can be reduced by varying the number of antenna ports for resources supported by subband precoding. Furthermore, by making the number of antenna ports the same for all SRS resources, UL DCI overhead can be reduced with the same wideband TPMI.

[0242] An example has been proposed in which the SRS resource field for subband precoding and the diversity-based SRS resource field are supported based on the same field, and the indication of the corresponding field is different based on the DCI, MAC CE, and / or RRC field. An example has been proposed in which the indication of the corresponding field is different, and the SRS resource field can be shared with fields other than the diversity-based field and the subband precoding field. For example, in the case of rank>1 transmission, if it is possible to indicate multiple SRS resources or SRS sets for supporting different beams corresponding to each layer, the same field can be used to perform the indication.

[0243] <Examples 1-7>

[0244] The base station may indicate to the UE whether to use diversity transmission by the following method, so as to determine whether the UE uses diversity transmission.

[0245] ●Diversity transmission usage indication method 1: via DCI indication

[0246] ●Diversity transmission use indication method 2: Indicate RRC or MAC CE

[0247] ● Diversity transmission usage indication method 3: Indicate to the UE through the number of SRS resources

[0248] Diversity transmission usage indication method 1 is a method for indicating the use of diversity transmission via DCI. When a base station schedules uplink data transmission for a UE, it can transmit information such as TRI, wideband TPMI, and resource allocation via UL DCI as described above. Furthermore, the base station can indicate whether diversity transmission is used using a single bit. For example, if this bit is 0, the base station indicates the use of one precoder or a number of precoders equal to the number of ranks; whereas, if this bit is 1, the base station indicates the use of diversity transmission or precoder cycling.

[0249] When a UE receives an indication of diversity transmission via one bit of preconfigured information, for example, the preconfigured subband TPMI information may be identified via the subband TPMI information within the same DCI, the subband TPMI information of a second DCI, or a MAC CE; or the preconfigured subband TPMI information may be identified via RRC. In this case, if the UE receives the subband TPMI via the MAC CE or RRC, the corresponding subband TPMI information may be configured based on each SRS resource that may be indicated to the UE or has been configured, and the UE may identify the subband TPMI via the corresponding one bit of information and the indicated SRS resource.

[0250] Diversity transmission usage indication method 2 indicates whether diversity transmission is used via RRC or MAC CE. By configuring whether diversity transmission is used in the UE via RRC or MAC CE, the UE can identify whether the corresponding diversity transmission is used. In this case, the advantage is that the amount of UL DCI information sent by the base station to the UE is reduced, thereby ensuring UL DCI coverage.

[0251] Diversity transmission usage indication method 3 is a method of indirectly indicating whether diversity transmission is used by indicating the number of SRS resources to the UE. As described above, in order to perform SRS-based diversity transmission, indications of multiple SRS resources or resource sets are required. Therefore, the UE can perform diversity transmission only when multiple corresponding SRS resources or resource sets are indicated. In addition, the operation can only be performed when the operation is configured to be performed through RRC. At this time, the DCI bit used for SRS indication can be determined by the maximum number of SRS resources that can be indicated, so as to reduce the number of blind decodings of DCI. If the SRS indication is not sent, a non-sending indication can be provided by a specific fixed value (for example, 0 means that SRS is not indicated).

[0252] In addition, the diversity transmission usage indication method may include a combination of multiple methods. For example, if both indication methods 2 and 3 are satisfied (if the use of diversity transmission is pre-configured via RRC, and the number of indicated and configured SRS resources is greater than a predetermined number), diversity transmission may be performed. In another example, if all of indication methods 1, 2, and 3 are satisfied, diversity transmission may be performed.

[0253] In order to indicate the above-mentioned multiple SRS resources, the indication field shown in [Table 7] may be used to indicate the SRS set.

[0254] [Table 7]

[0255] SRS indicator notify 00 SRS Set 1 01 SRS Set 2 10 SRS Set 3 11 SRS Set 4

[0256] Information about which SRS resources each SRS set indicates through RRC or MAC CE can be configured through a bitmap. If this field is used, the DCI overhead generated by the SRS resource indication can be reduced, and the SRS resources can be indicated efficiently.

[0257] In addition, one bit in the DCI can be used to indicate whether multiple SRS resources are indicated. As described above, when broadband precoding is supported, one SRS resource is indicated. At this time, in transmission based on one SRS resource, the beam direction is more important than in transmission based on multiple SRS resources, and therefore, a greater degree of freedom may be required. On the other hand, with a large degree of freedom, the indication of multiple SRS resources generates too much DCI overhead. Therefore, if one bit of the one-bit DCI field is 0, the SRS indication field can indicate one SRS resource; and if one bit is 1, the SRS indication field can indicate multiple SRS resources, or multiple SRS set indication fields similar to the example in [Table 7] can be used to indicate multiple SRS resources.

[0258] <Examples 1-7>

[0259] When <Embodiment 1-1> to <Embodiment 1-4> are applied to a UE, the method can be applied differently depending on the waveform used by the UE. If DFT-S OFDM is used, <Embodiment 1-1> and <Embodiment 1-4> may not be supported, but if CP-OFDM is used, both embodiments can be applied. Therefore, if CP-OFDM is used, one or both of <Embodiment 1-1> and <Embodiment 1-4> can be supported, and if DFT-S OFDM is used, <Embodiment 1-2> and <Embodiment 1-3> can be supported. In addition, if CP-OFDM is used, all available diversity transmissions can be supported; whereas if DFT-S OFDM is used, only <Embodiment 1-2> and <Embodiment 1-3> can be supported.

[0260] <Examples 1-8>

[0261] The relationship between precoding, DMRS and SRS can be defined as follows.

[0262] ● Precoding, DMRS and SRS relationship definition method 1: The relationship is defined based on the sequence indicated to the UE through DCI.

[0263] ● Method 2 for defining the relationship between precoding, DMRS, and SRS: indirectly defining the relationship through the SRS resource ID.

[0264] ● Method 3 for defining the relationship between precoding, DMRS, and SRS: The base station directly defines the relationship to the UE through RRC configuration or MAC CE configuration.

[0265] Method 1 for defining the relationship between precoding, DMRS, and SRS defines the relationship based on a sequence indicated to the UE via DCI. According to this method, based on the precoding indicated to the UE, the precoding of the first layer is indicated by a first-indicated DMRS port and SRS resource, and the precoding of the second layer is indicated by a second-indicated DMRS port and SRS resource. That is, the beam based on the precoding and SRS resource of the first layer indicated to the UE is associated with the DMRS first indicated by the base station. This method allows the base station to flexibly configure diversity-based transmission in the DMRS ports and SRS resources without requiring additional overhead from the UE.

[0266] Method 2 for defining the relationship between precoding, DMRS, and SRS indirectly defines the relationship through the SRS resource ID. Specifically, the lower-level precoding in the indicated precoding information is applied to the DMRS port with the lowest port number and the SRS resource with the lowest SRS resource ID within the indicated DMRS. This method has the advantage of reducing indication overhead and implementation complexity.

[0267] Precoding, DMRS, and SRS relationship definition method 3 is a method in which the BS directly defines the relationship with the UE through RRC or MAC CE configuration. Which precoding layer is mapped to the DMRS port can be preconfigured according to the order indicated by the RRC field.

[0268] In addition, multiple methods can be used together for the precoding, DMRS, and SRS relationship definition method. For example, the combination of definition methods 1 and 2 is a method of applying the DMRS port with a low port number and the precoding of the lower layer to the DMRS and indicating the SRS in the indicated order. In addition, the following method can be used: applying the precoding of the port with a low number and the lower layer to the DMRS, and applying the configuration to the SRS through RRC or MAC CE.

[0269] According to an embodiment of the present disclosure, various sequences such as a gold sequence, a pseudorandom noise (PN) sequence, a ZC sequence, and a constant amplitude zero autocorrelation waveform sequence may be applied to the DMRS. In addition, according to an embodiment, it is assumed that a DMRS pattern is configured on 8 REs in one symbol, but various patterns such as 6 REs may be used.

[0270] The embodiment is performed based on uplink diversity transmission, but can be used for downlink and sidelink diversity transmission.

[0271] To apply the embodiments, layer shifting may be considered when the transmission rank is greater than 1. For example, in the case of rank 2, it is assumed that if transmission is performed using precoder 0, DMRS ports 0 and 1 are sequentially used for layers 0 and 1; and if transmission is performed using precoder 1, DMRS ports 1 and 0 are sequentially used for layers 0 and 1. This principle can be equally applied to transmissions of higher ranks greater than or equal to 3.

[0272] Furthermore, the ranks available for diversity transmission may be limited because as the number of ranks in diversity transmission increases, the corresponding diversity gain decreases.

[0273] In order to implement the above embodiments of the present disclosure, Figure 16 and Figure 17 The transmitter, receiver, and processor of each of the UE and the base station are shown in FIG. The receiver, processor, and transmitter of the base station and the UE should operate according to the embodiments in order to implement the embodiments.

[0274] Figure 16 1 is a block diagram showing the internal structure of a UE according to an embodiment of the present disclosure. Figure 16 As shown, the UE according to the present disclosure may include a UE receiver 1610, a UE transmitter 1620, and a UE processor 1630. In the embodiments of the present disclosure, the UE receiver 1610 and the UE transmitter 1620 may be collectively referred to as a transceiver. The transceiver can transmit and receive signals to and from a base station. The signals may include control information and data. To this end, the transceiver includes: an RF transmitter that up-converts and amplifies the frequency of the transmitted signal; an RF receiver that performs low-noise amplification and down-converts the frequency of the received signal, etc. In addition, the transceiver can receive signals through a radio channel, output the signals to the UE processor 1630, and transmit signals output from the UE processor 1630 through a radio channel.

[0275] The UE processor 1630 may control a series of processes to enable the UE to operate according to the above-described embodiments of the present disclosure. For example, the UE receiver 1610 may receive a signal including information indicating signal transmission timing from a base station, and the UE processor 1630 may perform control to analyze the signal transmission timing. Thereafter, the UE transmitter 1620 transmits a signal at that timing.

[0276] Figure 17 FIG is a block diagram of the internal structure of a base station (BS) according to an embodiment of the present disclosure. Figure 17As shown, a base station according to the present disclosure may include a base station receiver 1710, a base station transmitter 1720, and a base station processor 1730. The base station receiver 1710 and the base station transmitter 1720 are generally referred to as transceivers in the embodiments of the present disclosure. The transceiver can transmit and receive signals to and from the UE. The signals may include control information and data. To this end, the transceiver includes: an RF transmitter that up-converts and amplifies the frequency of the transmitted signal; an RF receiver that performs low-noise amplification and down-converts the frequency of the received signal, etc. In addition, the transceiver can receive signals via a radio channel, output the signals to the base station processor 1730, and transmit signals output from the base station processor 1730 via a radio channel.

[0277] The base station processor 1730 may control a series of processes to enable the base station to operate according to the above-described embodiments of the present disclosure. For example, the base station processor 1730 may determine a processing method and perform control to generate processing method information to be sent to the UE. Thereafter, the base station transmitter 1720 may transmit this information to the UE.

[0278] In addition, according to an embodiment of the present disclosure, the base station processor 1730 may perform control to generate downlink control information including reference signal processing information for uplink precoding.

[0279] <Second embodiment>

[0280] Wireless communication systems have evolved into broadband wireless communication systems that provide high-speed and high-quality packet data services beyond the voice-based services provided in the initial stages, such as communication standards such as 3GPP's High Speed ​​Packet Access (HSPA), Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA), LTE-Advanced (LTE-A), 3GPP2's High Rate Packet Data (HRPD), Ultra Mobile Broadband (UMB), and IEEE's 802.16e. 5G or New Radio (NR) communication standards are under study as fifth-generation wireless communication systems.

[0281] The LTE system, which is a representative example of a broadband wireless communication system, utilizes an orthogonal frequency division multiplexing (OFDM) scheme for the downlink (DL) and a single-carrier frequency division multiple access (SC-FDMA) scheme for the uplink (UL). The uplink is a radio link through which a user equipment (UE) (or mobile station (MS)) sends data or control signals to a base station (BS) (or eNodeB (eNB)), and the downlink is a radio link through which a base station sends data or control signals to a UE. In this multiple access scheme, time-frequency resources for carrying data or control information are allocated and operated in a manner to prevent overlap of resources between users (i.e., to establish orthogonality) in order to identify the data or control information of each user. In the following, the LTE system may include LTE and LTE-A systems.

[0282] In the event of a decoding failure during initial transmission, the LTE system utilizes Hybrid Automatic Repeat Request (HARQ), which retransmits the corresponding data at the physical layer. In the HARQ scheme, when the receiver fails to accurately decode data, it sends information (a negative acknowledgement: NACK) to inform the transmitter of the decoding failure, allowing the transmitter to retransmit the corresponding data at the physical layer. The receiver combines the data retransmitted by the transmitter with the previously decoded data, thereby improving data reception performance. Furthermore, when the receiver accurately decodes the data, it sends information (an acknowledgment: ACK) to inform the transmitter of the decoding success, allowing the transmitter to send new data.

[0283] Figure 18 The basic structure of a time-frequency region is shown, which is a radio frequency region in which data or control channels are transmitted in the downlink of the LTE system.

[0284] exist Figure 18 In FIG, the horizontal axis indicates the time domain and the vertical axis indicates the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol. One time slot 1806 consists of N symb OFDM symbols 1802, and one subframe 1805 consists of two time slots. The length of one time slot is 0.5 ms, and the length of one subframe is 1.0 ms. A radio frame 1814 is a time region interval consisting of 10 subframes. The minimum transmission unit in the frequency region is a subcarrier, and the bandwidth of the entire system transmission band includes a total of N BW 1804 subcarriers.

[0285] The basic unit of resources in the time-frequency domain is a resource element (RE) 1802 and can be indicated by an OFDM symbol index and a subcarrier index. A resource block (RB or physical resource block (PRB)) 1808 consists of N symb consecutive OFDM symbols 1802 and N in the frequency domainRB 1808 is defined by N consecutive subcarriers 1810. Therefore, one RB 1808 includes N symb ×N RB RE 1812. Usually, the minimum transmission unit of data is RB unit. Usually, in LTE system, N symb =7 and N RB =12. N BW Proportional to the system transmission bandwidth. The data transmission rate increases in proportion to the number of RBs scheduled to the UE.

[0286] The LTE system defines and operates six transmission bandwidths. In the case of a frequency division duplex (FDD) system that operates by separating the downlink and uplink according to frequency, the downlink transmission bandwidth and the uplink transmission bandwidth may be different from each other. The channel bandwidth may indicate the RF bandwidth corresponding to the system transmission bandwidth. [Table 8] indicates the relationship between the system transmission bandwidth and the channel bandwidth defined in the LTE system. For example, when the LTE system has a channel bandwidth of 10 MHz, the transmission bandwidth may consist of 50 RBs.

[0287] [Table 8]

[0288] Channel bandwidth BWChannel[MHz] 1.4 3 15 10 15 20 <![CDATA[Transmission Bandwidth Configuration N RB > 6 5 25 50 75 100

[0289] Figure 19 The basic structure of a time-frequency region according to the prior art is shown. The time-frequency region is a radio resource region for transmitting data or a control channel in an uplink of an LTE system.

[0290] refer to Figure 19 , the horizontal axis indicates the time domain and the vertical axis indicates the frequency domain. The minimum transmission unit in the time domain is an SC-FDMA symbol 1902, and a time slot 1906 consists of N symb SC-FDMA symbols. One subframe 1905 consists of two time slots. The minimum transmission unit in the frequency domain is the subcarrier, and the entire system transmission band (transmission bandwidth) 1904 consists of a total of N BW Subcarriers. BW Has a value proportional to the system transmission band.

[0291] The basic unit of resources in the time-frequency domain is a resource element (RE) 1912 and can be defined by an SC-FDMA symbol index and a subcarrier index. A resource block (RB) 1908 consists of N symb N consecutive SC-FDMA symbols and frequency regions BW Therefore, RB is defined by N consecutive subcarriers. symb ×N RBThe PUCCH is mapped to a frequency region corresponding to one RB and can be transmitted during one subframe.

[0292] Figure 20 1 shows the radio resource of one RB, which is the minimum unit of scheduling in the downlink of the LTE system. Figure 20 In the radio resources shown, a plurality of different types of signals described below can be transmitted.

[0293] 1. Cell-specific RS (CRS) 2000: refers to a reference signal periodically transmitted to all UEs belonging to one cell and can be commonly used by multiple UEs.

[0294] 2. Demodulation Reference Signal (DMRS) 2010: This is a reference signal sent to a specific UE and is only sent when data is being sent to that UE. DMRS may include a total of eight DMRS ports. In LTE systems, ports 7 to 14 correspond to DMRS ports, and the ports are orthogonal to prevent interference between them through CDM or FDM.

[0295] 3. Physical Downlink Shared Channel (PDSCH) 2020: Used when the base station sends traffic to the UE through the following data channel, which is sent through the downlink and is used in Figure 20 It is sent in the RE that sends the reference signal in the data area.

[0296] 4. Channel State Information Reference Signal (CSI-RS) 2040: refers to a reference signal transmitted to UEs belonging to a cell and is used to measure channel status. Multiple CSI-RSs can be transmitted in a cell.

[0297] 5. Other channels (Physical Hybrid ARQ Indicator Channel (PHICH), Physical Control Format Indicator Channel (PCFICH), and Physical Downlink Control Channel (PDCCH)) 2030: These channels are used to provide the UE with control information required to receive the PDSCH or to transmit ACK / NACK for HARQ operations for uplink data transmission. These channels are transmitted in the control region 2050.

[0298] Figure 21 An example of a method for generating DMRS is shown. Figure 21 As shown, DMRS is generated from a pseudo-random (PN) sequence based on a gold sequence of length 31. More specifically, as Figure 21As shown, the PN sequence C(n) can be generated by concatenating a first m-sequence x1(n) generated from the polynomial D31+D3+1 of the higher register and a second m-sequence x2(n) generated from the polynomial D31+D3+D2+D+1 of the lower register, and the processor can be represented by [Equation 9].

[0299] [Equation 9]

[0300] c(n)=(x1(n+N C )+x2(n+N C ))mod2

[0301] x1(n+31)=(x1(n+3)+x1(n))mod2

[0302] x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod2

[0303] N c =1600, register initialization is performed as follows.

[0304] The first m-sequence x1(n) generated from the upper register is initialized to a fixed pattern of x1(0)=1, x1(n)=0, n=1, 2, . . . , 30.

[0305] Under the scrambling conditions required for each signal, the second m-sequence x2(n) generated from the lower register is initialized to the following [Equation 10].

[0306] [Equation 10]

[0307]

[0308] More specifically, in case of DMRS, [Equation 10] may be expressed as the following [Equation 11] so that the DMRS port p=5 is transmitted.

[0309] [Equation 11]

[0310]

[0311] In the above equation, n s Indicates the time slot number within the transmission frame, and n RNTI Indicates UE ID. Denotes a cell ID. Unlike this, [Equation 10] can be expressed by the following [Equation 12] so that DMRS ports p∈{7, 8, ..., 14} are transmitted.

[0312] [Equation 12]

[0313]

[0314] In the equation, n s Indicates the time slot number within the transmission frame, n SCID represents a scramble ID having a value of 0 or 1, and unless otherwise specified, the value of the scramble ID is assumed to be 0. Determine as follows.

[0315] ●If senior management does not provide or if DCI format 1A, 2B, or 2C is used for the DCI associated with the PDSCH transmission, then

[0316] Otherwise

[0317] As described above, in the case of DMRS, initialization is performed in each subframe, and a reference signal for transmitting DMRS port p∈{7, 8, ..., 14} is represented by [Equation 13].

[0318] [Equation 13]

[0319]

[0320] Indicates the maximum number of RBs supported for downlink in the LTE system. In the case of the LTE system, since a fixed DMRS pattern is used for each of the normal CP and the extended CP, the DMRS sequence as shown in [Equation 13] can be generated considering the number of DMRS REs per PRB.

[0321] However, unlike the LTE system, the 5G wireless communication system considers supporting a configurable DMRS structure as well as increased cell IDs, increased channel bandwidth, various subcarrier spacings, slot-based transmission and slot aggregation, and DMRS time bundling. If such various matters are configured, the DMRS sequence generation method may also be different. The DMRS sequence of the NR system can be UE-specifically generated, transmit and receive point (TRP)-specifically generated, or resource-specifically generated. Therefore, the DMRS operation method may be different. Therefore, the present disclosure proposes a DMRS sequence generation method that reflects this situation.

[0322] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Although the embodiments of the present disclosure are described as examples of LTE or LTE-A systems, the embodiments of the present disclosure can also be applied to other communication systems with similar technical backgrounds or channel forms. For example, the 5th generation mobile communication technology (5G, New Radio (NR)) developed after LTE-A can be included therein. In the NR system, the basic structure of the time-frequency area for transmitting downlink and uplink signals can be the same as Figure 18 and Figure 19 The basic structure of the present invention is different, and the types of signals sent in the downlink and uplink may also be different. However, based on the determination of those skilled in the art, the embodiments of the present invention can be applied to other communication systems through some modifications without departing from the scope of the present invention.

[0323] In the following description of the present disclosure, when a detailed description of a known function or configuration incorporated herein may make the subject matter of the present disclosure unclear, its detailed description will be omitted. The terms described below are defined in consideration of the functions in the present disclosure and may vary depending on the user, the user's intention, or custom. Therefore, the definition of terms should be based on the content of the entire specification.

[0324] In the following, a base station is an entity that allocates resources to a UE and may be one of an eNodeB, a Node B, a base station (BS), a radio access unit, a base station controller, and a node on a network. UEs may include user equipment (UE), mobile stations (MS), cellular phones, smart phones, computers, and multimedia systems capable of performing communication functions. In the present disclosure, a downlink (DL) refers to a wireless transmission path for signals sent from a base station to a UE, and an uplink (UL) refers to a wireless transmission path for signals sent from a UE to a base station.

[0325] In the following description, a demodulation reference signal (DMRS) is a reference signal having the following characteristics: with this characteristic, the UE can perform demodulation without additionally receiving precoding information after transmitting a reference signal to which UE-specific precoding is applied, and its name used in the LTE system can be used directly. However, the term DMRS can be interchanged with other terms depending on the user's intention and the purpose of using the reference signal. For example, DMRS can be interchanged with UE-specific signal (UE-specific RS) or dedicated reference signal (dedicated RS).

[0326] More specifically, the term DMRS is only used to easily describe the technology of the present disclosure and to help understand specific examples of the present disclosure, and it is obvious to those skilled in the art that operations can be performed using other terms based on the technical concepts of the present disclosure. The terms single-user multiple input multiple output (SU-MIMO) or multi-user MIMO (MU-MIMO) are also used to easily describe the technology of the present disclosure and to help understand the present disclosure, and it is obvious to those skilled in the art that operations of the present disclosure can be performed using other terms or without the terms.

[0327] <Example 2-1>

[0328] <Embodiment 2-1> describes a method of transmitting DMRS according to multiple orthogonal DMRS antenna ports.

[0329] Specifically, reference will be made to Figure 22A and Figure 22B To describe the DMSR structure proposed by the present disclosure. Figure 22A An example of a unit DMRS structure proposed by the present disclosure is shown. The advantages of a unit DMRS structure based on one OFDM symbol are that it configures the position of the reference signal for various transmission time intervals (TTIs), supports low latency, configures the position of the reference signal for URLLC, and is advantageous in terms of scalability (such as antenna port expansion).

[0330] like Figure 22A As shown, based on the PRB which is the minimum transmission unit of data, 12 subcarriers can be included in one OFDM symbol. The density of DMRS subcarriers (SC) can be configured in one OFDM symbol as indicated by reference numerals 2210, 2220, and 2230. Reference numerals 2210 and 2220 indicate DMRS structures in which four and eight DMRS SCs are included in twelve subcarriers, respectively; and reference numeral 2230 indicates a DMRS structure in which all subcarriers are used as DMRS SCs. Figure 22A The use of the proposed DMRS structure is not limited to data channels.

[0331] DMRS structure 2210 can be used in environments where a small number of DMRS SCs are configured and therefore support a small number of antenna ports or where the channel variation over frequency is small. DMRS structure 2210 can be used for mini-slots or control channels that require a relatively low DMRS density. In contrast, DMRS structure 2220 can be used in environments where a large number of DMRS SCs are configured and therefore support a large number of antenna ports or where the channel variation over frequency is large. Furthermore, DMRS structure 2220 can be used to improve channel estimation performance by increasing DMRS density in low signal-to-noise ratio (SNR) regions.

[0332] Although a fixed DMRS pattern can be used for each of the normal CP, extended CP, and multicast broadcast single frequency network (MBSFN) subframes in the LTE system, in the NR system, the proposed DMRS pattern 2220 can be used for the extended CP or MBSFN DMRS. As indicated by reference numerals 2210 and 2220, configuring the DMRS with an even number of DMRS SCs may have the following advantages: if spaced frequency block coding (SFBC) of the transmit diversity scheme is considered, no orphan REs are generated.

[0333] In the DMRS structures 2210 and 2220, the SCs not used as DMRS SCs can be used for data or another signal (such as another reference signal), or can be nulled for DMRS power boosting. If the SCs not used as DMRS SCs are nulled for DMRS power boosting, the performance of DMRS channel estimation in low SNR areas can be improved. In addition, the DMRS structures 2210 and 2220 have subcarriers that do not transmit DMRS, and therefore, a portion thereof can be used as direct current (DC) subcarriers.

[0334] For example, considering various parameter sets, Figure 22B Reference numerals 2240 , 2250 , and 2260 describe a method of using a DC subcarrier with the DMRS structure 2220 . Figure 22B An example of arranging a DC subcarrier according to the DMRS structure proposed in the present disclosure is shown. The DMRS structure 2210 may use the same method as that indicated by reference numerals 2240 , 2250 , and 2260 .

[0335] In the case where various parameter sets can be multiplexed in time in the NR system, the following cases are shown: a case where a signal is transmitted with a subcarrier spacing of f0 configured at time t0, a case where a signal is transmitted with a subcarrier spacing of 2*f0 configured at time t1, and a case where a signal is transmitted with a subcarrier spacing of 4×f0 configured at time t2. As shown in the figure marks 2240, 2250 and 2260, if a specific SC that is not used as a DMRS SC is configured as a DC subcarrier, the DMRS structure of the present disclosure has the advantage that there is no need to change the position of the DC subcarrier according to the change in the subcarrier spacing over time. However, since DMRS is transmitted in all subcarriers in the DMRS structure 2230, some of the subcarriers need to be punctured to transmit DC.

[0336] The DMRS SCs shown in reference numerals 2210 to 2230 can be generated based on a pseudo-random sequence or a Zadoff-Chu (ZC) sequence. More specifically, the DMRS structures 2210 and 2220 can be used in a cyclic prefix (CP)-OFDM system. In addition, the DMRS structure can be configured and used at the same time-frequency position in the uplink / downlink. If the uplink and downlink have the same DMRS structure, the uplink and downlink DMRS ports can be allocated to be orthogonal, making it possible to improve interference cancellation performance by further improving channel estimation performance in a flexible duplex environment.

[0337] On the other hand, similar to the LTE system, the DMRS structure 2230 is based on a Zadoff-Chu (ZC) sequence and can be used for the uplink in the case of a discrete Fourier transform spread OFDM (DFT-s-OFDM) system. In this case, similar to the LTE system, a low peak-to-average power ratio (PAPR) can be obtained. However, the present disclosure is not limited to the method using the proposed structures 2210 to 2230. For example, the DMRS structure 2230 can be used for all of CP-OFDM, DFT-s-OFDM, and uplink / downlink.

[0338] Figure 23 Shows the mapping of antenna ports to Figure 22A An example of the proposed method of unit DMRS structure. For convenience, Figure 23 In

[15] , antenna ports are represented as p = A, B, C, D, ... However, antenna port numbers can be represented as other numbers. The mapping of antenna ports will support multiple layers of transmission and rank. Therefore, the antenna port mapping described below can be related to another term "layer transmission" or "rand support".

[0339] Specifically, reference numerals 2300 and 2305 indicate a case where two antenna ports are mapped to DMRS structure 2210. Reference numeral 2300 indicates a method for mapping two antenna ports p=A, B in frequency division multiplexing (FDM) and code division multiplexing (CDM) schemes by applying an orthogonal cover code (OCC) having a length of 2; whereas reference numeral 2300 indicates a method for mapping two antenna ports p=A, B without applying an OCC. Specifically, reference numerals 2310 and 2315 indicate a case where two antenna ports are mapped to DMRS structure 2220. Since DMRS 2220 has a higher reference signal density than DMRS 2210, channel estimation performance can be improved. Reference numeral 2310 indicates a method for mapping two antenna ports p=A, B in FDM and CDM schemes by applying an OCC having a length of 2; whereas reference numeral 2315 shows a method for mapping two antenna ports p=A, B without applying an OCC.

[0340] Reference numerals 2320 and 2325 indicate a case where four antenna ports are mapped to the DMRS structure 2220. In this case, to improve channel estimation performance, the subcarriers in the DMRS structure 2220 through which DMRS is not transmitted are left blank and used for DMRS power boosting. Reference numeral 2320 represents a method of mapping four antenna ports p = A, B, C, D using an FDM scheme and an OCC having a length of 2, while reference numeral 2325 shows a method of mapping four antenna ports p = A, B, C, D using an FDM scheme without applying an OCC. Reference numerals 2330 and 2335 indicate a case where six antenna ports are mapped to the DMRS structure 2220. In this case, to improve channel estimation performance, the subcarriers in the DMRS structure 2220 through which DMRS is not transmitted are left blank and used for DMRS power boosting. Reference numeral 2330 indicates a method of mapping six antenna ports p=A, B, C, D, E, F in FDM and CDM schemes by applying an OCC having a length of 2; and reference numeral 2335 shows a method of mapping six antenna ports p=A, B, C, D, E, F in the FDM scheme without applying OCC.

[0341] As indicated by reference numerals 2330 and 2335, the method of mapping antenna ports has a characteristic different from the above-described antenna port mapping method in that the density of reference signals (RSs) for each antenna port is inconsistent. This is because in the method for allocating antenna ports for MU-MIMO, each UE has a different channel state. In this case, ports with low RS density can be allocated to UEs with good channel states, and ports with high RS density can be allocated to UEs with poor channel states.

[0342] Reference numerals 2340 and 2345 indicate a case where eight antenna ports are mapped to DMRS structure 2220. In this case, to improve channel estimation performance, subcarriers in DMRS structure 2220 through which DMRS is not transmitted are left blank and used for DMRS power boosting. Reference numeral 2340 indicates a method for mapping eight antenna ports p = A, B, C, D, E, F, G, H in FDM and CDM schemes by applying an OCC having a length of 2, while reference numeral 23000 shows a method for mapping eight antenna ports p = A, B, C, D, E, F, G, H in FDM schemes without applying OCC. An advantage of applying OCC to the frequency domain is that power imbalance issues do not exist in reference numerals 2300, 2310, 2320, 2330, and 2340. In LTE systems, power imbalance issues may arise if OCC is applied to the time domain, and therefore different OCCs are used for each PRB within two PRBs.

[0343] Finally, reference numeral 2350 shows the DMRS structure 2230. In the DMRS structure 2230, all 12 subcarriers are used as DMRS, so that a method of supporting orthogonal DMRS antenna ports using a Zadoff-Chu (ZC) sequence can be considered. At this time, as in the LTE system, based on the assumption that the subcarrier spacing is 15 kHz, a maximum of eight orthogonal antenna ports can be supported by applying eight cyclic shift (CS) fields. In another method of using the DMRS structure 2230, a method of supporting four orthogonal antenna ports by applying an FDM scheme with a subcarrier spacing of four can be considered. The present disclosure is not limited to the method of mapping antenna ports to the proposed DMRS structures 2300 to 2350.

[0344] Figure 24 shows that a larger number of antenna ports are mapped to Figure 23 An example of the proposed method of unit DMRS structure. In order to map a larger number of antenna ports, DMRS can be configured to additionally apply time division multiplexing (TDM), FDM and / or CDM to Figure 22A For example, as indicated by reference numerals 2410 and 2420, a larger number of antenna ports can be mapped in time by TDM of structure 2220. If TDM is used to expand orthogonal antenna ports, there is an advantage of maintaining RS density in frequency, but there is a disadvantage of increasing DMRS density in a transmission unit (one PRB).

[0345] To maintain a low DMRS density within a transmission unit, a method of extending orthogonal antenna ports using FDM or CDM can be considered based on the assumption that a high rank is supported in an environment with very good channel conditions and low frequency selectivity. For example, a larger number of antenna ports can be mapped to frequency using FDM in structure 2220, as shown in reference numerals 2430 and 2440. However, if the number of antenna ports is extended using FDM, there may be a disadvantage that the transmission unit is extended to several PRBs. As indicated by reference numerals 2450 and 2460, a larger number of antenna ports can be mapped by applying an OCC with an extended length. More specifically, reference numeral 2450 indicates a method of multiplexing eight antenna ports using an OCC with a length of 8, as indicated by reference numeral 2220; while reference numeral 2460 indicates a method of multiplexing twelve antenna ports using an OCC with the length in structure 2230. The OCC can be generated as a Walsh-Hadamard code.

[0346] If all subcarriers are configured as DMRS SCs, as indicated by reference numeral 2230, various antenna port expansions can be performed depending on the antenna port mapping method applied to structure 2230, as described above. Assuming a subcarrier spacing of 15 kHz, and supporting eight orthogonal antenna ports by cyclically shifting the ZC sequence in reference numeral 2230, expansion to 16 orthogonal antenna ports is possible by applying TDM, as indicated by reference numeral 2140. If FDM is used with a spacing of four subcarriers in reference numeral 2230, a maximum of four orthogonal antenna ports can be supported. However, if TED is considered, as indicated by reference numeral 2410, a maximum of eight orthogonal antenna ports can be supported. Alternatively, if additional TDM is considered, as indicated by reference numeral 2420, a maximum of 12 orthogonal antenna ports can be supported.

[0347] This disclosure is not limited to Figure 24 The antenna port expansion method presented. The antenna port expansion method can be applied by a combination of TDM, FDM and CDM, and orthogonal antenna ports can be expanded by various methods. For example, as described above, if only TDM is used to expand the antenna port as indicated by reference numeral 2410 or 2420, there is a disadvantage that the DMRS density in the transmission unit increases. In a method of compensating for this disadvantage, TDM can be applied to two consecutive time slots as indicated by reference numeral 2470, and CDM can be applied to two consecutive time slots as indicated by reference numeral 2480 using an OCC having a length of 4. As indicated by reference numerals 2470 and 2480, the above description is made based on two time slots, but the time unit for applying TDM or CDM in reference numerals 2470 and 2480 is not limited to the time slot.

[0348] If a DMRS is generated using a ZC sequence, unlike the method of mapping a maximum of eight antenna ports by applying an OCC having a length of 8 (as indicated by reference numeral 2450), a CS can be used to support additional antenna ports, as indicated by reference numeral 2490. For example, if a CS is used while multiplexing onto four antenna ports using FDM and CDM as indicated by reference numeral 2320, additional antenna port expansion is possible. If four CS fields are generated, the number of antenna ports can be expanded to a maximum of 16. If a CS is used instead of the OCC indicated by reference numeral 2490, there is an advantage in maintaining RS density over frequency.

[0349] In a 5G communication system, multiple DMRS structures can be configured. For example, the configurable DMRS structure can be divided into a front-loaded DMRS and an extended or additional (hereinafter, extended) DMRS.

[0350] Specifically, the front-loaded DMRS is a DMRS located at the front of the NR-PDSCH for fast data decoding, and may include one or two adjacent OFDM symbols. In addition, the front-loaded DMRS is located at the front of the NR-PDSCH and its position may be fixed or flexible. For example, if the position of the front-loaded DMRS is determined to be the starting first symbol of the NR-PDSCH, the front-loaded RS may be flexibly changed by the area of ​​the NR-PDCCH. The advantages of the case where the position of the front-loaded DMRS is fixed and flexible will be described. If the position of the front-loaded DMRS is fixed, it can be assumed that the DMRS of the next cell is always sent at the same position. However, if the area of ​​the control channel can be configured or if the DMRS of the data channel is not located earlier in the subframe where the control channel is not sent, the front-loaded DMRS may be weaker in terms of decoding delay.

[0351] If the position of the frontloaded DMRS is flexible, the frontloaded RS is always located at the front of the data channel, thus offering an advantage in decoding latency. However, due to the variable position of the frontloaded RS, the DMRS position within a cell is not fixed, potentially leading to issues with interference control and advanced receiver operation. To address this, additional methods involving network signaling can be considered, but configuring a fixed DMRS position is generally more advantageous for system operation. Therefore, a detailed method for configuring a fixed frontloaded DMRS position is proposed.

[0352] Figure 25The position of the pre-loaded DMRS is shown in the case where the time slot length is 7 or 14 OFDM symbols. The configuration of the position of the pre-loaded DMRS can be determined by the region of the control channel. If the region of the control channel consists of a maximum of two OFDM symbols, the pre-loaded DMRS is located at the third OFDM symbol, as indicated by reference numeral 2510. If the region of the control channel consists of a maximum of three OFDM symbols, the pre-loaded DMRS is located at the fourth OFDM symbol, as indicated by reference numeral 2520. As described above, if the position of the pre-loaded DMRS is determined by the maximum number of regions of control channels that can be configured, there may be a loss in reducing decoding delay when control channels are not configured in all regions.

[0353] Therefore, as an extension method, the present disclosure proposes a method for configuring the position of the front-loaded DMRS. For example, if the area of ​​the control channel consists of a maximum of two OFDM symbols, the operation of fixing the front-loaded DMRS to the third OFDM symbol as indicated by reference numeral 2510, and the operation of fixing the front-loaded DMRS to the first OFDM symbol as indicated by reference numeral 2530 can be configured together. If such two options are configured according to the situation, the disadvantage of the situation where the position of the front-loaded DMRS is fixed can be compensated. Specifically, the configuration of multiple positions of the front-loaded DMRS can be performed in various ways. For example, a method of semi-static configuration through high-layer signaling such as RRC can be considered. In another method, the position can be configured through system information such as a master information block (MIB) or a system information block (SIB). In addition, a method of dynamically configuring the position through DCI can be considered. Different from this, the position can be configured through semi-persistent scheduling (SPS).

[0354] The extended DMRS will be described later. Because it cannot track rapidly changing channels in high Doppler conditions, the front-loaded DMRS has difficulty accurately estimating the channel. Furthermore, frequency offset cannot be corrected using only the front-loaded DMRS. Therefore, for this reason, an additional DMRS must be transmitted after the front-loaded DMRS in the time slot.

[0355] Figure 26 The positions where the extended DMRS are transmitted are shown in the case where the slot length is 7 or 14 OFDM symbols. Figure 26The extended DMRS is shown for each of reference numerals 2510, 2520, and 2530, which show the location of the frontloaded DMRS. The location of the extended DMRS is configured to avoid the location where the CRS is transmitted in the LTE system, as indicated by reference numerals 2610 to 2660. This may be advantageous in terms of being affected by the LTE-NR coexistence state. However, in the cases of reference numerals 2670 to 2690, the location of the frontloaded DMRS overlaps with the location where the CRS is transmitted in the LTE system, as in reference numeral 2530.

[0356] Although if the slot length is 7 OFDM symbols, the number of locations of the extended DMRS can be configured as follows Figure 26 However, if the slot length is 14 OFDM symbols, the number of extended DMRS positions may need to be configured as two depending on the Doppler state. For example, in an environment where the channel changes rapidly, the position of the extended DMRS may be configured as indicated by reference numeral 2620; and in an environment where the channel changes very rapidly, the position of the extended DMRS may be configured as indicated by reference numeral 2630.

[0357] Figure 25 and Figure 26 The embodiment shows that based on Figure 22A The basic position of the DMRS in the unit DMRS structure is shown, and if Figure 24 As described above, the unit DMRS structure is extended for antenna port expansion, and the location of the DMRS can be additionally configured. When the DMRS is extended, DMRS overhead may be generated because multiple DMRSs are configured in time. Therefore, in this case, DMRS overhead can be reduced by configuring DMRSs with low density in frequency, as indicated by reference numeral 2210.

[0358] Hereinafter, a method for configuring a DMRS structure by a base station according to the present disclosure taking into account various DMRS structures will be described. Specifically, according to the present disclosure, as the number of supported orthogonal antenna ports increases, the DMRS port multiplexing method may be different. In addition, different RS densities may be configured in frequency within a unit DMRS structure. Like extended DMRS, the front-loaded RS structure and the extended RS structure may be configured in time. Therefore, if the base station configures a DMRS structure suitable for the transmission environment, its configuration should be signaled to the UE to allow the UE to accurately perform channel estimation based on the configured DMRS structure. The DMRS structure may be configured semi-statically or dynamically. The simplest method for semi-statically configuring a DMRS structure is to configure the DMRS structure through high-layer signaling. More specifically, as shown in [Table 9] below, the configuration information may be inserted into the RS-related signaling field of the RRC.

[0359] [Table 9]

[0360]

[0361] Specifically, in [Table 9], mapping information can be indicated in different modes by DMRS-PatternId. maxDMRS-Pattern indicates the maximum number of DMRS-PatternIds that can be configured. For example, it should be noted that in this embodiment, the mapping mode is different when 12 orthogonal DMRS ports are mapped for MU-MIMO and when 8 orthogonal DMRS ports are mapped. In this case, DMRS-PatternId can be used to indicate different pattern information. Specifically, DMRS-PatternId is configured as (0, 1), in which case 0 can indicate a mode that supports 8 ports for SU-MIMO, and 1 can indicate a mode that supports 12 ports for MU-MIMO. In another example, DMRS-PatternId is configured as (0, 4, 8, 12), in which case 0 can indicate a DMRS mode operating with SU-MIMO, and 4, 8, and 12 can indicate DMRS modes corresponding to 4, 8, and 12 used DMRS antenna ports, respectively. At this time, if DMRS-PatternId is configured as 12, only the DMRS pattern for MU-MIMO can be indicated.

[0362] In addition, the extended RS structure in time can be indicated by the DMRS-timeDensityId in [Table 9]. maxDMRS-Time indicates the maximum number of DMRS-timeDensityId that can be configured. For example, maxDMRS-Time can be used to configure the front-loaded RS and extended RS structure in time, just like the extended DMRS. Finally, different RS densities in frequency can be configured by the DMRS-frequencyDensityId in [Table 9]. maxDMRS-Freqeuncy indicates the maximum number of DMRS-frequencyDensityId that can be configured. For example, DMRS-frequencyDensityId can be used to configure a low RS density in frequency in order to control RS overhead.

[0363] The field value item configured in [Table 9] can be replaced with another item. This item is used only for a specific example to easily describe the technology of the present disclosure and to help understand the present disclosure, and does not limit the scope of the present disclosure. That is, it is obvious to those skilled in the art that operations can be performed using another item based on the technical concept of the present disclosure. With this method, the DMRS structure can be semi-statically configured through RRC, and the UE can detect the structure of the currently transmitted DMRS through the value configured in RRC.

[0364] Next, we will describe a method by which a base station dynamically configures a DMRS structure suitable for the transmission environment. If information about the DMRS is configured through a MAC CE using a method similar to the method for configuring DMRS information through RRC, information about the DMRS structure can be configured more dynamically. The simplest method for dynamically configuring the DMRS structure is to transmit DCI containing information about the DMRS structure. In this case, a DCI format can be defined separately for basic operations, in which fields for dynamically operating the DMRS structure are not applied. Using DCI to configure the DMRS structure has the advantage of dynamically changing the DMRS structure. On the other hand, there is the disadvantage of generating DCI overhead for operation.

[0365] Therefore, the configuration of the DMRS structure can be performed in a hierarchical configuration structure corresponding to a combination of semi-static signaling and dynamic signaling. Specifically, in [Table 9], DMRS-timeDensityId and DMRS-frequencyDensityId can be configured through RRC, and DMRS-PatternId can be configured through MAC CE or DCI. This is because it is not necessary to change the DMRS pattern as quickly as required by dynamic signaling in accordance with channel changes in time and frequency, and therefore the DMRS pattern can be configured through RRC. It is necessary to dynamically operate the DMRS pattern for the SU and MU, and therefore, the DMRS pattern information for them can be configured through MAC CE or DCI.

[0366] <Example 2-2>

[0367] <Embodiment 2-2> proposes a method for efficiently operating a DMRS sequence when generating a DMRS sequence according to an increased DMRS sequence length in an NR system. As described above, when a DMRS sequence r(m) is generated based on a PN sequence C(n), the generated sequence length can be determined by the number A of DMRS REs within a PRB and the maximum number of RBs supporting DL or UL of the NR system. is determined as shown in the following [Equation 14].

[0368] [Equation 14]

[0369]

[0370] However, various DMRS structures can be supported in the NR system, and a method for efficiently generating DMRS sequences and mapping DMRS sequences to resources is required, taking into account various DMRS structures. In addition, the NR system supports various parameter sets and also considers supporting channel bandwidths up to 400 MHz. If the supported subcarrier spacing is 15, 30, 60, 120, 240, and 480 kHz and the channel bandwidth is 5, 10, 40, 80, 100, 200, and 400 MHz, the maximum number of subcarriers and the maximum number of RBs are as shown in [Table 10] and [Table 11].

[0371] [Table 10]

[0372]

[0373] [Table 11]

[0374]

[0375]

[0376] The number of subcarriers and the number of RBs presented in [Table 10] and [Table 11] are merely examples, and different values ​​may be used depending on the progress of NR standardization. Referring to [Table 10] and [Table 11], the maximum number of RBs supported by the NR system may have different values ​​depending on the supported subcarrier spacing and channel bandwidth, and if the maximum number of supportable subcarriers is assumed to be 6600, the maximum number of RBs may increase to 550. On the other hand, if the same channel bandwidth is used but the subcarrier spacing is increased, the maximum number of supported RBs decreases. Therefore, a method for efficiently operating the DMRS sequence length according to the various numbers of supported RBs is needed.

[0377] First, a method of determining the number A of DMRS REs within a PRB will be described with reference to [Equation 14]. Specifically, since the NR system supports various DMRS structures, the following alternatives can be considered as a method of efficiently generating a DMRS sequence.

[0378] • Method 1: A is determined as the number of DMRS REs of the DMRS pattern with the highest RE density, including different DMRS patterns in various DMRS structures.

[0379] ● Method 2: A is determined as the number of DMRS REs of the front-loaded DMRS pattern in various DMRS structures.

[0380] Among the alternatives, method 1 is a method of determining A as the number of DMRS REs of a DMRS pattern with the highest RE density (including different DMRS patterns in various DMRS structures), and generating a DMRS sequence, but using only a portion of the sequence in the case of a DMRS pattern with a lower RE density. More specifically, in the case of Figure 25 and Figure 26 In the description of reference numerals 2510, 2610, 2620, and 2630, a DMRS sequence is generated based on a DMRS pattern having the highest RE density in method 1, as indicated by reference numeral 2630. If a DMRS pattern having a lower RE density is used as indicated by reference numerals 2510, 2610, and 2620, only some of the generated patterns may be mapped to resources.

[0381] Different from this, method 2 is a method of determining A as the number of DMRS REs of the front-loaded DMRS pattern in various DMRS structures and generating a DMRS sequence, but reusing and extending the generated sequence in the case where the DMRS pattern has a higher RE density. More specifically, in the case of Figure 25 and Figure 26 In the description of reference numerals 2510, 2610, 2620, and 2630, a DMRS sequence is generated based on the frontloaded DMRS pattern in method 2, as indicated by reference numeral 2510. If a DMRS pattern with a higher RE density is used as indicated by reference numerals 2610, 2620, and 2630, the generated sequence of the frontloaded DMRS pattern may be repeatedly mapped to resources for extended DMRS.

[0382] If Figure 22A As shown, in Method 2, if all of the unit DMRS patterns with different densities in frequency are supported, a sequence can be generated based on the unit DMRS pattern with a higher density. More specifically, if both reference numerals 2210 and 2220 are supported, when a sequence is generated based on reference numeral 2220 and a unit DMRS pattern with a lower density is configured as indicated by reference numeral 2210, a portion of the generated sequence can be punctured and the remaining sequence can be mapped to the resource. Compared to Method 1, Method 2 has the advantage of operating with a shorter DMRS sequence.

[0383] Next, the maximum value of the number of RBs supported for DL ​​or UL in [Equation 14] will be described. As described above, the maximum number of RBs supported by the NR system varies depending on the supported subcarrier spacing and the supported channel bandwidth, and the maximum number of supportable RBs can be significantly increased compared to the LTE system. Therefore, a method for efficiently operating the DMRS sequence length according to the various numbers of supported RBs is needed. At this time, the following alternatives can be considered as a method for determining the DMRS sequence length.

[0384] ● Method 1: Consider the maximum bandwidth supported by the currently configured subcarrier spacing to configure

[0385] ● Method 2: Considering all subcarrier spacings and the maximum supported bandwidth defined in the NR system

[0386] Among the alternatives, method 1 is to configure the maximum bandwidth that can be supported in the currently configured subcarrier spacing. More specifically, in [Table 11], if the currently configured subcarrier spacing is 15 kHz, the number of RBs may be 550 in consideration of the maximum supportable bandwidth of 100 MHz. If the currently configured subcarrier spacing is 15 kHz, the number of RBs may be 220 in consideration of the maximum supportable bandwidth of 40 MHz. On the other hand, Method 2 is to configure the subcarrier spacing in consideration of the maximum supportable bandwidth among all subcarrier spacings defined in the NR system. The method makes it possible to convert [Table 11] The maximum number of RBs is 550.

[0387] In order to minimize the length of the DMRS sequence to be generated, all supported subcarrier spacings can be classified into <6GHz (below 6GHz) and >6GHz (above 6GHz) in Method 2. Specifically, in the case of <6GHz, the supported subcarrier spacing is limited to 15, 30, and 60kHz. In this case, The maximum number of RBs is configured as 550. However, in the case of >6GHz, the supported subcarrier spacing is limited to 120, 240 and 480kHz. In this case, The maximum number of RBs is 275, which is based on Table 11. According to Method 2, the number of RBs can be determined by considering only the subcarrier spacing and channel bandwidth supported by the base station. For example, if the base station supports subcarrier spacing limited to 15, 30, and 60kHz, and the supported channel bandwidth limited to 5, 10, and 40MHz, you can set Configured to 220, this is the maximum number of RBs in a set based on [Table 11].

[0388] However, even with this alternative, the length of the DMRS sequence to be generated can still be significantly longer than in current LTE systems. Therefore, to address this issue, the following approach can be considered. The proposed method uses two-step resource allocation. To prevent the RBG size from increasing due to the increased channel bandwidth, two-step resource allocation can be used.

[0389] Figure 27 An example of a two-step resource allocation method is shown. Specifically, Figure 27 As shown, if a system bandwidth corresponding to a maximum of 500 RBs is allocated, the two-step resource allocation method may configure resource allocation positions of 100 RBs among the 500 RBs through a 5-bit bitmap in the first step, and configure resource allocation positions of 4 RBs among the configured 100 RBs through a 25-bit bitmap in the second step as indicated by reference numeral 2710. Therefore, It is possible to reflect the two-step resource allocation instead of determining based on the maximum bandwidth currently allocated. More specifically, if the system bandwidth corresponding to the maximum 500 RBs is allocated in reference numeral 2710, then Instead of 500, it can be determined as 100 RBs, which is determined in the first step of the two-step resource allocation. The method can be applied to both method 1 and method 2.

[0390] <Example 2-3>

[0391] <Example 2-3> describes a method for TRP-specific generation and initialization of DMRS sequences in an NR system. The generation of TRP-specific DMRS sequences means that each TRP has a different DMRS sequence by generating the DMRS sequence using the TRP ID. Here, the transmit receive point (TRP) can be used to indicate a cell, and the TRP ID can be used to indicate a cell ID. In all embodiments of the present disclosure, the terms "TRP" and "cell" can be used interchangeably. The advantage of TRP-specific generation of DMRS sequences is that the mutual correlation of DMRS sequences between different TRPs is randomized as much as possible. On the other hand, in order to enable the UE to effectively remotely control the interference signal from another TRP, there is a disadvantage in that the UE should receive signaling of the DMRS information of another TRP, such as another TRP ID. The present disclosure proposes a detailed method for TRP-specific generation and initialization of DMRS sequences.

[0392] Specifically, <Embodiment 2-3> proposes a method of initializing a DMRS sequence using a cell ID, a slot number, and a scrambling identifier. The first method can be represented by the following equation.

[0393] [Equation 15]

[0394]

[0395] In the equation, n s Indicates the time slot number within the transmission frame, and n SCID Indicates the scrambling identifier and is assumed to be 0 unless otherwise specified. In the NR system, n SCID Can have two or more values. SCID In the example, the number of values ​​N may be configured to have two values ​​such as 0 and 1, taking into account DMRS sequence scrambling between two TRPs in CoMP operation as in the LTE system; or the number of values ​​N may be configured to have two or more values ​​such as i=0, 1, ..., N, taking into account more various operation environments than the NR system. For example, an extension of N=4 may be considered. In addition, X represents an identifier n SCID The number of bits, and can be determined as X = log2(N). It can be determined as follows.

[0396] ●If senior management does not provide or if the DCI associated with the PDSCH transmission is not supported SCID DCI format, then

[0397] Otherwise,

[0398] By using a method similar to the following [Table 12], you can configure the [Table 12] N_cellID represents the number of cell IDs and can be 504 in the LTE system and can be extended to 1000 in the NR system. [Table 12] shows an example of the following case: SCID The number is 4, and according to the consideration of NR system, 4n SCID Reduced to 2n SCID Or further increase. In [Equation 15], Y may be the number of bits for identifying a cell ID, and if the number of cell IDs is 1000, Y=10.

[0399] [Table 12]

[0400]

[0401]

[0402] Referring to Equation 15 above, the DMRS sequence is initialized in each slot. However, in NR systems, as the subcarrier spacing increases, the slot length becomes significantly shorter. More specifically, the slot length according to the subcarrier spacing (SCS) is shown in Table 13 below.

[0403] [Table 13]

[0404]

[0405] As shown in [Table 13] above, if the slot length becomes significantly shorter as the subcarrier spacing becomes larger, initialization of the DMRS sequence in each slot may be a burden for implementation. Therefore, in order to solve this problem, a modified equation is proposed below.

[0406] [Equation 16]

[0407]

[0408] In this equation, the description of all parameters except M is the same as that of [Equation 15]. In the equation, M is a parameter for controlling the initialization of the DMRS sequence depending on the slot length, and the value of M for DMRS sequence initialization based on a slot length of 1 ms can be as shown in [Table 14] below. The method of varying DMRS sequence initialization depending on the slot length in [Equation 16] can be expressed in another way. For example, based on the use of [Equation 15], the following phrases can be used.

[0409] It is expected that the UE does not update c for less than X msec (milliseconds) init .

[0410] Here, X=1 msec.

[0411] [Table 14]

[0412]

[0413]

[0414] Another method of generating and initializing a DMRS sequence specifically for a TRP can be represented by the following [Equation 17]. Compared with the method of [Equation 15], the following method is a method of further randomizing the cross-correlation of DMRS sequences between different TRPs. Specifically, assuming and is a PN sequence generated based on initialization values ​​of X1=first cell ID and X2=second cell ID, and and It is a PN sequence generated based on the initialization values ​​of X1+Z and X2+Z. Assume that Z is the time slot number. At this time, based on the assumption of time synchronization network, and The mutual correlation between and The cross-correlations between are the same. This means that if and There is a poor cross-correlation between and Therefore, in order to solve this problem, the modified equation is proposed below.

[0415] [Equation 17]

[0416]

[0417] In the above equation, except The description of all parameters except for is the same as that of [Equation 15]. In the above equation, we can use replace In the above equation, for use The reason is to use Can be compared to use The cross-correlation of DMRS sequences between different TRPs is further randomized. More specifically, when assuming that M1 and M2 are different cell IDs, consider the case where M2+1=2(M1+1). For example, the case corresponds to (0,1), (1,3), (2,5), (3,7), ... In this case, if To initialize the sequence, the cross-correlation between the I component corresponding to the cell ID M1 and the Q component corresponding to the cell ID M2 in [Equation 14] does not vary depending on the slot number. In this case, it is possible to use Solve the above problems.

[0418] Referring to Equation 17 above, the DMRS sequence is initialized in each slot. However, in NR systems, as the subcarrier spacing increases, the slot length becomes significantly shorter. As shown in Table 13 above, if the slot length becomes significantly shorter as the subcarrier spacing increases, initializing the DMRS sequence in each slot may be a burden for implementation. Therefore, to address this issue, a modified equation is proposed below.

[0419] [Equation 18]

[0420]

[0421] In this equation, the description of all parameters except M is the same as that of [Equation 17]. In the equation, M is a parameter for controlling the initialization of the DMRS sequence depending on the slot length, and the value of M for DMRS sequence initialization based on a slot length of 1 ms can be as shown in [Table 14] below. The method of varying DMRS sequence initialization depending on the slot length in [Equation 18] can be expressed in another way. For example, based on the use of [Equation 17], the following phrases can be used.

[0422] It is expected that the UE does not update c for less than X msec (milliseconds) init .

[0423] Here, X=1 msec.

[0424] Another method of generating and initializing a DMRS sequence specifically for a TRP can be represented by the following [Equation 19]. The following method is a modified method of [Equation 17] and avoids repeatedly using [Equation 17]. To do this, the following equation can be used.

[0425] [Equation 19]

[0426]

[0427] The description of all parameters in the equation is the same as that described in [Equation 15]. However, in NR systems, as the subcarrier spacing increases, the slot length becomes significantly shorter. As shown in [Table 13] above, if the slot length becomes shorter as the subcarrier spacing increases, initializing the DMRS sequence in each slot may be a burden for implementation. Therefore, to address this issue, a modified equation is proposed below.

[0428] [Equation 20]

[0429]

[0430] In this equation, the description of all parameters except M is the same as that of [Equation 19]. In the equation, M is a parameter for controlling the initialization of the DMRS sequence depending on the slot length, and the value of M for DMRS sequence initialization based on a slot length of 1 ms can be as shown in [Table 14] above. The method of varying DMRS sequence initialization depending on the slot length in [Equation 20] can be expressed in another way. For example, based on the use of [Equation 17], the following phrase can be used.

[0431] It is expected that the UE does not update c for less than X msec (milliseconds) init .

[0432] Here, X=1 msec.

[0433] <Example 2-4>

[0434] <Example 2-4> describes a method for resource-specifically generating and initializing a DMRS sequence in an NR system. If the DMRS sequence is generated resource-specifically, each TRP has the same DMRS sequence because the DMRS sequence is not generated using the TRP ID, which is different from <Example 2-3>. The DMRS sequence has different sequences in the allocated resource area. Therefore, this method has the disadvantage of increasing the cross-correlation of DMRS sequences between different TRPs. However, the advantage of this method is that the UE does not need to receive signaling of DMRS information of another TRP such as another TRP ID, thereby allowing the UE to effectively remotely control interference signals from another TRP.

[0435] This disclosure proposes a detailed method for resource-specifically generating and initializing a DMRS sequence. More specifically, <Example 2-4> proposes a method for initializing a DMRS sequence using a slot number and a scrambling identifier. The first method can be represented by the following [Equation 21].

[0436] [Equation 21]

[0437] c init =2 X (n s +1)+n SCID

[0438] In the equation, n s Indicates the time slot number within the transmission frame, and n SCID Indicates the scrambling identifier and is assumed to be 0 unless otherwise specified. In the NR system, n SCID Can have two or more values. SCID In the example, the number of values ​​N may be configured to have two values ​​such as 0 and 1, taking into account DMRS sequence scrambling between two TRPs in CoMP operation as in the LTE system; or the number of values ​​N may be configured to have two or more values ​​such as i=0, 1, ..., N, taking into account more various operation environments than the NR system. For example, an extension of N=4 may be considered. In addition, X represents an identifier n SCID The number of bits, and can be determined as X = log2(N).

[0439] Referring to Equation 21 above, the DMRS sequence is initialized in each slot. However, in NR systems, as the subcarrier spacing increases, the slot length becomes significantly shorter. As shown in Table 13 above, if the slot length becomes shorter as the subcarrier spacing increases, initializing the DMRS sequence in each slot may be a burden for implementation. Therefore, to address this issue, a modified equation is proposed below.

[0440] [Equation 22]

[0441]

[0442] In the above equation, the description of all parameters except M is the same as that of [Equation 21]. In the equation, M is a parameter for controlling the initialization of the DMRS sequence depending on the slot length, and the value of M for DMRS sequence initialization based on a slot length of 1 ms can be as shown in [Table 14] above. The method of varying the DMRS sequence initialization depending on the slot length in [Equation 22] can be expressed in another way. For example, based on the use of [Equation 21], the following phrases can be used.

[0443] It is expected that the UE does not update c for less than X msec (milliseconds) init .

[0444] Here, X=1 msec.

[0445] Another method of generating and initializing a DMRS sequence in a resource-specific manner can be represented by the following [Equation 23]. Compared with the method of [Equation 2m], the following method is a method of further randomizing the cross-correlation of DMRS sequences between different TRPs. Specifically, assuming and is a PN sequence generated based on initialization values ​​of X1=first cell ID and X2=second cell ID, and and It is a PN sequence generated based on the initialization values ​​of X1+Z and X2+Z. Assume that Z is the time slot number. At this time, based on the assumption of time synchronization network, and The mutual correlation between and The cross-correlations between are the same. This means that if and There is a poor cross-correlation between and Therefore, in order to solve this problem, the modified equation is proposed below.

[0446] [Equation 23]

[0447] cinit =2 X (n s +1)·(2n SCID +1)+n SCID In the above equation, divide 2n SCID The description of all parameters except +1 is the same as that of [Equation 21]. In the above equation, (n SCID +1) replace (2n SCID +1). In the above equation, use (2n SCID +1) because, using (2n SCID +1) can be used more efficiently than (n SCID +1) further randomizes the cross-correlation of DMRS sequences between different TRPs. More specifically, when assuming that M1 and M2 are different scrambling identifiers, consider the case where M2+1=2(M1+1). For example, the cases correspond to (0,1), (1,3), (2,5), (3,7), ... In this case, if (n SCID +1) to initialize the sequence, the cross-correlation between the I component corresponding to the cell ID M1 and the Q component corresponding to the cell ID M2 in [Equation 14] does not vary depending on the slot number. In this case, (2n SCID +1) for solving the above problem.

[0448] If [Equation 23] is applied, the DMRS sequence is initialized in each time slot. However, in NR systems, as the subcarrier spacing increases, the time slot length becomes significantly shorter. As shown in [Table 13] above, if the time slot length becomes significantly shorter as the subcarrier spacing increases, initializing the DMRS sequence in each time slot may be a burden for implementation. Therefore, to address this issue, a modified equation is proposed below.

[0449] [Equation 24]

[0450]

[0451] In the above equation, the description of all parameters except M is the same as that of [Equation 23]. In the equation, M is a parameter for controlling the initialization of the DMRS sequence depending on the slot length, and the value of M for DMRS sequence initialization based on a slot length of 1 ms can be as shown in [Table 14] above. The method of varying the DMRS sequence initialization depending on the slot length in [Equation 24] can be expressed in another way. For example, based on the use of [Equation 23], the following phrase can be used.

[0452] It is expected that the UE does not update c for less than X msec (milliseconds) init .

[0453] Here, X=1 msec.

[0454] <Example 2-5>

[0455] <Example 2-5> A detailed method for antenna port mapping based on a front-loaded DMRS pattern is proposed based on the current negotiation of 3GPP. The front-loaded DMRS pattern agreed by 3GPP can be divided into type 1 and type 2, which can be configured through high-layer signaling. The DMRS density may vary depending on the method of mapping the antenna port, which results in channel estimation performance, and therefore, an optimized mapping method according to each type is very important for DMRS design. If additional DMRS is transmitted in the transmission slot, the same DMRS pattern as the following DMRS pattern can be repeated after the front-loaded DMRS.

[0456] Configuration Type 1

[0457] ■One symbol: comb 2+2CS, up to 4 ports

[0458] ■ Two symbols: comb 2+2CS+TD-OCC ({1 1} and {1 -1}), up to 8 ports

[0459] ◆Note: It should be possible to schedule up to 4 ports without using both {1,1} and {1,-1}.

[0460] Configuration Type 2

[0461] ■One symbol: 2-FD-OCC on adjacent REs in the frequency domain, up to 6 ports

[0462] ■ Two symbols: 2-FD-OCC + TD-OCC on adjacent REs in the frequency domain (both {1,1} and {1,-1}), up to 12 ports)

[0463] ◆Note: It should be possible to schedule up to 6 ports without using both {1,1} and {1,-1}.

[0464] Figure 28 and Figure 29 The following details the pattern of antenna port mapping methods that vary based on negotiation. In the following embodiment, antenna port p is represented as p = P1 to P8 in Type 1 and p = P1 to P12 in Type 2. However, the port numbers can be displayed differently. For example, in Type 1, p = 1000 to 1007, while in Type 2, p = 1000 to 1011.

[0465] First, in the case of Type 1 mode, Comb 2 and 2CS are the basic structures as negotiated, while in the case of two-symbol mode, TD-OCC ({1 1} and {1 -1}) is applied and supports a maximum of 8 orthogonal DMRS ports. As described above, a method for supporting multiple antenna ports is applied, and DMRS can be mapped to the first OFDM symbol and the kth subcarrier in time, as shown in the following equation.

[0466] [Equation 25]

[0467]

[0468] k=k0+2m+Δ

[0469] l=l0+l′

[0470] In [Equation 25], r(m) represents the DMRS sequence generated in [Equation 14] of <Embodiment 2-2>, and w t (l′) denotes the application of TD-OCC to be applied to two symbol modes, and Indicates the phase used to apply 2CS. The following table details the values ​​that vary depending on the antenna port method.

[0471] Figure 28 An example of a pattern available in Type 1 according to the antenna port mapping method is shown. Reference numerals 2800 and 2802 indicate antenna ports that can be mapped to different frequency positions. Reference numerals 2810 and 2820 indicate an example of mapping a DMRS according to Type 1 to one symbol. Reference numeral 2810 corresponds to a mapping method according to a method in which DMRS ports P1 / P3 and P2 / P4 are separated by comb 2, while reference numeral 2820 corresponds to a mapping method according to a method in which DMRS ports P1 / P2 and P3 / P4 are separated by comb 2. In reference numerals 2810 and 2820, a maximum of two ports can be separated using 2CS within the same comb. Specifically, mapping method 2810 can have the following DMRS density.

[0472] ● When using 6 REs <= one layer of transmission

[0473] ●When using 12 REs> one layer of transmission

[0474] Different from the above, the mapping method 2820 may have the following DMRS density.

[0475] ● When using 6 REs <= two-layer transmission

[0476] ● In the case of using 12 REs > two-layer transmission

[0477] Therefore, methods 2810 and 2820 may have different DMRS densities depending on the number of transmitted DMRS ports.

[0478] Subsequently, reference numerals 2830 to 2870 illustrate examples of mapping Type 1 to two symbols. Reference numeral 2830 corresponds to a mapping method in which DMRS ports P1 / P3 / P5 / P7 and P2 / P4 / P6 / P8 are separated by a comb of 2, while reference numeral 2840 corresponds to a mapping method in which DMRS ports P1 / P3 / P5 / P6 and P2 / P4 / P7 / P8 are separated by a comb of 2. Reference numeral 2850 corresponds to a mapping method in which DMRS ports P1 / P2 / P5 / P7 and P3 / P4 / P6 / P8 are separated by a comb of 2, while reference numeral 2860 corresponds to a mapping method in which DMRS ports P1 / P2 / P5 / P6 and P3 / P4 / P7 / P8 are separated by a comb of 2. Finally, reference numeral 2870 corresponds to a mapping method according to a method in which DMRS ports P1 / P2 / P3 / P4 and P5 / P6 / P7 / P8 are separated by comb 2. In reference numerals 2830 to 2870, a maximum of four ports can be separated using 2CS and TD-OCC within the same comb.

[0479] Specifically, mapping methods 2830 and 2840 may have the following DMRS densities.

[0480] ● When using 12 REs <= one layer of transmission

[0481] ●When using 24 REs> one layer of transmission

[0482] Different from the above, mapping methods 2850 and 2860 may have the following DMRS density.

[0483] ● When using 12 REs <= two-layer transmission

[0484] ● In case of using 24 REs > two-layer transmission

[0485] Different from the above, the mapping method 2870 may have the following DMRS density.

[0486] ● When using 12 REs <= 4-layer transmission

[0487] ● When using 24 REs > Layer 4 transmission

[0488] According to the antenna port mapping method of Type 1, it is noted that DMRS density varies depending thereon, and one symbol pattern and two symbol patterns for DMRS may use different mapping patterns depending on the optimized mapping method.

[0489] More specifically, the following detailed method is presented: the configuration of the parameters in [Equation 25] is changed depending on which antenna port mapping method is used by one symbol pattern or two symbol patterns for DMRS. First, according to Figure 28 The antenna port mapping method shown can divide the available configuration methods of one symbol mode and two symbol modes for DMRS into 10 methods, and the configuration of the parameters in [Equation 25] is described by the following table.

[0490] ● Case 1: One symbol 2810 and two symbols 2830

[0491] ● Case 2: One symbol 2810 and two symbols 2840

[0492] ● Case 3: One symbol 2810 and two symbols 2850

[0493] ● Case 4: One symbol 2810 and two symbols 2860

[0494] ● Case 5: One symbol 2810 and two symbols 2870

[0495] ● Case 6: One symbol 2820 and two symbols 2830

[0496] ● Case 7: One symbol 2820 and two symbols 2840

[0497] ● Case 8: One symbol 2820 and two symbols 2850

[0498] ● Case 9: One symbol 2820 and two symbols 2860

[0499] ● Case 10: One symbol 2820 and two symbols 2870

[0500] In the case of two symbol modes, additional cases according to the 2CS and TD-OCC priorities applied to the antenna ports within the comb can be considered.

[0501] ● Method 1: In two symbol modes, first apply 2 CSs and then apply TD-OCC

[0502] ● Method 2: In two symbol modes, first apply TD-OCC and then apply 2CS

[0503] The following [Table 15-1] and [Table 15-2] show the configured values ​​of the parameters in [Equation 25] according to Case 1. [Table 15-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 1-1).

[0504]

Table 15-1

[0505]

[0506]

[0507] Table 15-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (cases 1-2). In Table 15-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of four ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0508]

Table 15-2

[0509]

[0510] The following [Table 16-1] and [Table 16-2] show the configured values ​​of the parameters in [Equation 25] according to Case 2. [Table 16-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 2-1).

[0511]

Table 16-1

[0512]

[0513]

[0514] Table 16-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 2-2). In Table 16-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 4 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0515]

Table 16-2

[0516]

[0517] [Table 17-1] and [Table 17-2] show configured values ​​of parameters in [Equation 25] according to Case 3. [Table 17-1] shows parameters configured by a method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 3-1).

[0518]

Table 17-1

[0519]

[0520]

[0521] Table 17-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 3-2). In Table 17-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of four ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0522]

Table 17-2

[0523]

[0524] The following [Table 18-1] and [Table 18-2] show the configured values ​​of the parameters in [Equation 25] according to Case 4. [Table 18-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 4-1).

[0525]

Table 18-1

[0526]

[0527]

[0528] Table 18-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 4-2). In Table 18-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of four ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0529]

Table 18-2

[0530]

[0531] [Table 19-1] and [Table 19-2] show configured values ​​of parameters in [Equation 25] according to Case 5. [Table 19-1] shows parameters configured by a method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 5-1).

[0532]

Table 19-1

[0533]

[0534]

[0535] Table 19-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 5-2). In Table 19-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of four ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0536]

Table 19-2

[0537]

[0538] The following [Table 20-1] and [Table 20-2] show the configured values ​​of the parameters in [Equation 25] according to Case 6. [Table 20-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 6-1).

[0539]

Table 20-1

[0540]

[0541]

[0542] Table 20-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 6-2). In Table 20-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 4 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0543]

Table 20-2

[0544]

[0545] The following [Table 21-1] and [Table 21-2] show the configured values ​​of the parameters in [Equation 25] according to Case 7. [Table 21-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 7-1).

[0546]

Table 21-1

[0547]

[0548]

[0549] Table 21-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 7-2). In Table 21-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 4 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0550]

Table 21-2

[0551]

[0552] The following [Table 22-1] and [Table 22-2] show the configured values ​​of the parameters in [Equation 25] according to Case 8. [Table 22-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 8-1).

[0553]

Table 22-1

[0554]

[0555]

[0556] Table 22-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 8-2). In Table 22-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 4 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0557]

Table 22-2

[0558]

[0559] The following [Table 23-1] and [Table 23-2] show the configured values ​​of the parameters in [Equation 25] according to Case 9. [Table 23-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 9-1).

[0560]

Table 23-1

[0561]

[0562]

[0563] Table 23-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 9-2). In Table 23-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 4 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0564]

Table 23-2

[0565]

[0566] The following [Table 24-1] and [Table 24-2] show the configured values ​​of the parameters in [Equation 25] according to Case 10. [Table 24-1] shows the parameters configured by the method of first applying 2CS and then applying TD-OCC in two symbol modes (Case 10-1).

[0567]

Table 24-1

[0568]

[0569]

[0570] Table 24-2 shows the parameters configured by first applying TD-OCC and then applying 2CS in two symbol patterns (case 10-2). In Table 24-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of four ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0571]

Table 24-2

[0572]

[0573] The parameters in [Table 15] to [Table 24] correspond to the parameter values ​​in [Equation 25], and note that the equations and some values ​​may be expressed differently if the same effect can be obtained by different expressions.

[0574] Next, in the case of Type 2 mode, FD-OCC in two frequency-adjacent REs is the basic structure as negotiated, while in the case of two-symbol mode, TD-OCC ({11} and {1-1}) is applied and supports a maximum of 12 orthogonal DMRS ports. As described above, a method for supporting multiple antenna ports is applied, and DMRS can be mapped to the first OFDM system and the kth subcarrier in time, as shown in the following equation.

[0575] [Equation 26]

[0576]

[0577] k=k0+6m+k′+Δ

[0578] l=l0+l′

[0579] In [Equation 26], r(m) represents the DMRS sequence generated in [Equation 14] of <Embodiment 2-2>, and w t (l′) denotes the application of TD-OCC to two symbol modes, and w f (k′) indicates that 2-FD-OCC is applied in frequency-adjacent REs. The following table presents in detail the values ​​that vary depending on antenna port mapping.

[0580] Figure 29 An example of a pattern available in Type 2 according to the antenna port mapping method is shown. Reference numerals 2900, 2902, and 2904 indicate antenna ports that can be mapped to different frequency positions. Reference numerals 2910 and 2920 indicate an example of mapping Type 2 to one symbol. Reference numeral 2910 corresponds to a mapping method according to a method in which DMRS ports P1 / P2, P3 / P4, and P5 / P6 are separated by FDM, while reference numeral 2920 corresponds to a mapping method according to a method in which DMRS ports P1 / P4, P2 / P5, and P3 / P6 are separated by FDM. In reference numerals 2910 and 2920, two ports mapped to two adjacent REs in frequency can be separated using FD-OCC. Specifically, mapping method 2910 can have the following DMRS density.

[0581] ● When using 4 REs <= 2-layer transmission

[0582] ● When using 8 REs > two-layer transmission and <= four-layer transmission

[0583] ● When using 12 REs > four-layer transmission

[0584] Different from the above, the mapping method 2920 may have the following DMRS density.

[0585] ●When using 4 REs, one layer of transmission

[0586] ● In the case of using 8 REs, two-layer transmission

[0587] ● In case of using 12 REs > two-layer transmission

[0588] Accordingly, methods 2910 and 2920 may have different DMRS densities depending on the number of transmitted DMRS ports.

[0589] Subsequently, reference numerals 2930 to 2970 illustrate examples of mapping Type 2 to two symbols. Reference numeral 2930 corresponds to a mapping method in which DMRS ports P1 / P3 / P5 / P7 and P2 / P4 / P6 / P8 are separated by FDM, while reference numeral 2940 corresponds to a mapping method in which DMRS ports P1 / P3 / P5 / P6 and P2 / P4 / P7 / P8 are separated by FDM. Reference numeral 2950 corresponds to a mapping method in which DMRS ports P1 / P2 / P5 / P7 and P3 / P4 / P6 / P8 are separated by FDM, while reference numeral 2960 corresponds to a mapping method in which DMRS ports P1 / P2 / P5 / P6 and P3 / P4 / P7 / P8 are separated by FDM. Finally, reference numeral 2970 corresponds to a mapping method according to a method in which DMRS ports P1 / P2 / P3 / P4 and P5 / P6 / P7 / P8 are separated by FDM. In reference numerals 2930 to 2970, the number of ports that can be separated by FD-OCC and TD-OCC and mapped to two adjacent REs in frequency can be a maximum of four. Specifically, mapping methods 2930 and 2940 can have the following DMRS densities.

[0590] ● When using 8 REs <= two-layer transmission

[0591] ● When using 8 REs > two-layer transmission and <= four-layer transmission

[0592] ● When using 24 REs > Layer 4 transmission

[0593] Different from the above, mapping methods 2950 and 2960 may have the following DMRS density.

[0594] ●When using 8 REs, one layer of transmission

[0595] ● In the case of using 12 REs, two-layer transmission

[0596] ● In case of using 24 REs > two-layer transmission

[0597] Different from the above, the mapping method 2970 may have the following DMRS density.

[0598] ● When using 8 REs <= Layer 4 transmission

[0599] ● When using 12 REs > four-layer transmission and <= eight-layer transmission

[0600] ● When using 24 REs > 8 layers of transmission

[0601] According to the antenna port mapping method of Type 2, it is noted that DMRS density varies depending thereon, and depending on the optimized mapping method, one symbol pattern and two symbol patterns for DMRS may use different mapping patterns.

[0602] More specifically, the following detailed method is presented: the configuration of the parameters in [Equation 26] is changed depending on which antenna port mapping method is used by one symbol pattern or two symbol patterns for DMRS. First, according to Figure 29 The antenna port mapping method shown can divide the available configuration methods of one symbol mode and two symbol modes for DMRS into 10 methods, and the configuration of the parameters in [Equation 26] is described by the following table.

[0603] ● Case 1: One symbol 2910 and two symbols 2930

[0604] ● Case 2: One symbol 2910 and two symbols 2940

[0605] ● Case 3: One symbol 2910 and two symbols 2950

[0606] ● Case 4: One symbol 2910 and two symbols 2960

[0607] ● Case 5: One symbol 2910 and two symbols 2970

[0608] ● Case 6: One symbol 2920 and two symbols 2930

[0609] ● Case 7: One symbol 2920 and two symbols 2940

[0610] ● Case 8: One symbol 2920 and two symbols 2950

[0611] ● Case 9: One symbol 2920 and two symbols 2960

[0612] ● Case 10: One symbol 2920 and two symbols 2970

[0613] Furthermore, two symbol patterns may consider additional cases according to the priorities of FD-OCC and TD-OCC applied to antenna ports within two adjacent REs in frequency.

[0614] ● Method 1: In two symbol modes, first apply FD-OCC and then apply TD-OCC

[0615] ● Method 2: In two symbol modes, first apply TD-OCC and then apply FD-OCC

[0616] The following [Table 25-1] and [Table 25-2] show the configured values ​​of the parameters in [Equation 26] according to Case 1. [Table 25-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 1-1).

[0617]

Table 25-1

[0618]

[0619] Table 25-2 shows the parameters configured by first applying TD-OCC to two symbol patterns and then applying TD-OCC (cases 1-2). In Table 25-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 6 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0620]

Table 25-2

[0621]

[0622]

[0623] The following [Table 26-1] and [Table 26-2] show the configured values ​​of the parameters in [Equation 26] according to Case 2. [Table 26-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 2-1).

[0624]

Table 26-1

[0625]

[0626] Table 26-2 shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 2-2). In Table 26-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 6 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0627]

Table 26-2

[0628]

[0629] The following [Table 27-1] and [Table 27-2] show configured values ​​of parameters in [Equation 26] according to Case 3. [Table 27-1] shows parameters configured by a method of first applying FD-OCC and then applying TD-OCC in two symbol modes.

[0630]

Table 27-1

[0631]

[0632]

[0633] [Table 27-2] shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 3-2). In [Table 27-2], two symbols (*) consider the case of repeating one symbol pattern and scheduling a maximum of 6 ports in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0634]

Table 27-2

[0635]

[0636]

[0637] The following [Table 28-1] and [Table 28-2] show the configured values ​​of the parameters in [Equation 26] according to Case 4. [Table 28-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 4-1).

[0638]

Table 28-1

[0639]

[0640] [Table 28-2] shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 4-2). In [Table 28-2], two symbols (*) consider the case of repeating one symbol pattern and scheduling a maximum of 6 ports in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0641]

Table 28-2

[0642]

[0643]

[0644] (*) Schedule up to 6 ports in two symbols

[0645] The following [Table 29-1] and [Table 29-2] show the configured values ​​of the parameters in [Equation 26] according to Case 5. [Table 29-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 5-1).

[0646]

Table 29-1

[0647]

[0648] [Table 29-2] shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 5-2). In [Table 29-2], two symbols (*) consider the case of repeating one symbol pattern and scheduling a maximum of 6 ports in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0649]

Table 29-2

[0650]

[0651] The following [Table 30-1] and [Table 30-2] show the configured values ​​of the parameters in [Equation 26] according to Case 6. [Table 30-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 6-1).

[0652]

Table 30-1

[0653]

[0654]

[0655] Table 30-2 shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 6-2). In Table 30-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 6 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0656]

Table 30-2

[0657]

[0658] The following [Table 31-1] and [Table 31-2] show the configured values ​​of the parameters in [Equation 26] according to Case 7. [Table 31-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 7-1).

[0659]

Table 31-1

[0660]

[0661] Table 31-2 shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 7-2). In Table 31-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 6 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0662]

Table 31-2

[0663]

[0664]

[0665] The following [Table 32-1] and [Table 32-2] show the configured values ​​of the parameters in [Equation 26] according to Case 8. [Table 32-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 8-1).

[0666]

Table 32-1

[0667]

[0668] Table 32-2 shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 8-2). In Table 32-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 6 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high-frequency bands.

[0669]

Table 32-2

[0670]

[0671] The following [Table 33-1] and [Table 33-2] show the configured values ​​of the parameters in [Equation 26] according to Case 9. [Table 33-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 9-1).

[0672]

Table 33-1

[0673]

[0674] Table 33-2 shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 9-2). In Table 33-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 6 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0675]

Table 33-2

[0676]

[0677] The following [Table 34-1] and [Table 34-2] show the configured values ​​of the parameters in [Equation 26] according to Case 10. [Table 34-1] shows the parameters configured by the method of first applying FD-OCC and then applying TD-OCC in two symbol modes (Case 10-1).

[0678]

Table 34-1

[0679]

[0680]

[0681] Table 34-2 shows the parameters configured by first applying TD-OCC and then applying FD-OCC in two symbol patterns (case 10-2). In Table 34-2, two symbols (*) consider a case where a symbol pattern is repeated and a maximum of 6 ports are scheduled in two symbols. This is a method that takes into account the difficulty of applying TD-OCC to high frequency bands.

[0682]

Table 34-2

[0683]

[0684] The parameters in [Table 25] to [Table 34] above correspond to the parameter values ​​in [Equation 26], and note that the equations and some values ​​may be expressed differently if the same effect can be obtained by different expressions.

[0685] <Example 2-6>

[0686] <Example 2-6> proposes a DMRS power boosting method based on the DMRS pattern described in <Example 2-5>. Note that the DMRS power boosting method may vary depending on the DMRS pattern. Figure 28 As shown, in the case of a type 1 DMRS pattern, comb 2 and 2 CSs may be used, and if the number of data transmission layers is greater than 2, transmission may be performed with DMRS power increased twice as much as that of data.

[0687] Figure 30 An example of DMRS transmission for Type 1 DMRS pattern is shown.

[0688] Specifically, as indicated by reference numeral 3010, if the number of data transmission layers is 4, in the case of reference numeral 2810, DMRS is transmitted only through two ports in the RE in which DMRS is transmitted, so that transmission can be performed with twice the power. This applies to Figure 28 As mentioned above, in case of Type 1 DMRS pattern, DMRS power boost can be expressed as the ratio of energy per resource element (EPRE) of PDSCH (data) to UE-specific RS (DMRS), as described below.

[0689] • For DMRS configuration type 1, if there is a UE-specific RS in the PRB on which the corresponding PDSCH is mapped, the UE may assume a ratio of PDSCH EPRE to UE-specific RS EPRE within each OFDM symbol containing the UE-specific RS.

[0690] ■For the number of transmission layers less than or equal to 2, 0dB,

[0691] ■ and -3dB otherwise.

[0692] Different from the above, Figure 29 As shown, in the case of the type 2 DMRS pattern, OCC is applied to two adjacent REs in frequency, and if the number of transmission layers is greater than 2, transmission can be performed with DMRS power increased twice as much as that of data. If the number of data transmission layers is greater than 4, transmission can be performed with DMRS power increased three times as much as that of data. Specifically, as shown in reference numeral 3020, if the number of data transmission layers is 6, in the case of reference numeral 2910, DMRS is transmitted only through two ports in the RE in which DMRS is transmitted, so that transmission can be performed with power increased three times. This applies to Figure 29 As mentioned above, in case of Type 2 DMRS pattern, DMRS power boost can be expressed as the ratio of EPRE of PDSCH (data) to UE-specific RS (DMRS), as described below.

[0693] • For DMRS configuration type 1, if there is a UE-specific RS in the PRB on which the corresponding PDSCH is mapped, the UE may assume a ratio of PDSCH EPRE to UE-specific RS EPRE within each OFDM symbol containing the UE-specific RS.

[0694] ■For the number of transmission layers less than or equal to 2, 0dB,

[0695] ■For the number of transmission layers less than or equal to 2, -3dB,

[0696] ■ and otherwise, -4.77dB.

[0697] <Example 2-7>

[0698] <Example 2-7> proposes a DMRS information signaling method based on the DMRS pattern described in <Example 2-5>. The DMRS signaling method may vary depending on the DMRS pattern. The DMRS signaling information may include the following.

[0699] ●Number of layers and port numbers

[0700] SCID (Scrambled ID)

[0701] ●One symbol and two symbol indicators.

[0702] The number of layers and the port number are information required for SU / MU dynamic switching and MU operation. As described in <Example 2-5>, the type 1 DMRS mode is a method of supporting a maximum of four ports in one symbol and a maximum of eight ports in two symbols, while the type 2 DMRS mode is a method of supporting a maximum of six ports in one symbol and a maximum of twelve ports in two symbols. Therefore, the DMRS patterns of type 1 and type 2 have different total numbers of orthogonal DMRS layers and different port numbers. In addition, the SCID is a parameter that can be used for coordinated multi-point (CoMP) operation, and can be used as a virtual cell ID and identify DMRS from adjacent cells. Although one bit of SCID is used in the LTE system, the number of SCID bits may increase in the NR system. Finally, one symbol and two symbol indicators have a DMRS pattern consisting of one symbol or two symbols. Since two symbols can be configured even in low-layer transmission, the base station should signal information about it to the UE using one bit.

[0703] Among the information, the number of layers, port numbers, and SCIDs are information that needs to be dynamically switched and, therefore, should be dynamically signaled via DCI. However, the one-symbol and two-symbol indicators can be configured by a higher layer or dynamically signaled via DCI. If the one-symbol and two-symbol indicators are configured by a higher layer, the operation of the DMRS using one or two symbols may be limited.

[0704] Hereinafter, the difference between Type 1 and Type 2 will be described based on the signaling method according to the number of layers and port numbers among the DMRS information. More specifically, in the following embodiments, the number of bits described below is used to signal information about the number of layers and port numbers for Type 1 and Type 2.

[0705] ● Type 1: The number of layers and port number à 4 bits.

[0706] ● Type 2: The number of layers and port numbers à 5 bits.

[0707] At this time, the amount of information per bit is different depending on the configuration of Type 1 and Type 2, so that the total number of DCI bits may vary depending on whether the DMRS pattern is configured by a higher layer as Type 1 or Type 2. Alternatively, by zero padding, the number of required DCI bits can be configured to fit on the larger side in the case of Type 1 or Type 2.

[0708] As described above, the Type 1 DMRS mode is a method of supporting a maximum of four ports in one symbol and a maximum of eight ports in two symbols, and [Table 35] shows a DMRS table design method when the maximum number of MU-MIMO layers supported per UE is 2, in the case of supporting MU-MIMO using eight orthogonal ports for the Type 1 DMRS mode.

[0709] [Table 35]

[0710]

[0711] Unlike the above, [Table 36] shows a DMRS table design method when the maximum number of MU-MIMO layers supported per UE is 4, in the case of supporting MU-MIMO using eight orthogonal ports for Type 1 DMRS pattern.

[0712] [Table 36]

[0713]

[0714] As described above, the Type 2 DMRS pattern is a method of supporting a maximum of six ports in one symbol and a maximum of eight ports in two symbols, and [Table 37] shows a DMRS table design method when the maximum number of MU-MIMO layers supported per UE is 2, in the case of supporting MU-MIMO using twelve orthogonal ports for the Type 2 DMRS pattern. In this case, the number of cases where the number of MU-MIMO layers supported per UE is 1 is represented as 12, and the number of cases where the number of MU-MIMO layers supported per UE is 2 is represented as 6.

[0715] [Table 37]

[0716]

[0717] Unlike the above, [Table 38] shows a DMRS table design method when the maximum number of MU-MIMO layers supported per UE is 4, in the case of supporting MU-MIMO using twelve orthogonal ports for the type 2 DMRS pattern. In this case, the number of cases where the number of MU-MIMO layers supported per UE is 1 is represented as 12, the number of cases where the number of MU-MIMO layers supported per UE is 2 is represented as 6, the number of cases where the number of MU-MIMO layers supported per UE is 3 is represented as 4, and the number of cases where the number of MU-MIMO layers supported per UE is 2 is represented as 3.

[0718] [Table 38]

[0719]

[0720]

[0721] Tables 37 and 38 above use two columns to show one codeword (CW) transmission and two CW transmissions, respectively. However, information about the number of antenna ports and transmission layers can be signaled using only one column as shown in Tables 39 and 40. In Tables 39 and 40, it is assumed that 2 CW transmission is marked, but 1 CW transmission is not marked separately.

[0722] Specifically, [Table 39] is a modified form from [Table 30] and shows a DMRS table design method based on one column when the maximum number of MU-MIMO layers supported per UE is 2 in a case where MU-MIMO is supported using twelve orthogonal ports; and [Table 40] is a modified form from [Table 31] and shows a DMRS table design method based on one column when the maximum number of MU-MIMO layers supported per UE is 4 in a case where MU-MIMO is supported using twelve orthogonal ports. The signaling methods proposed in [Table 39] and [Table 40] can be considered as a method for preventing many reserved indexes that are not used for 2CW in [Table 30] and [Table 31].

[0723] [Table 39]

[0724]

[0725]

[0726] [Table 40]

[0727]

[0728]

[0729] <Example 2-8>

[0730] <Example 2-8> Based on the methods proposed in <Example 2-5>, <Example 2-6> and <Example 2-7> above, the operations of the UE and the base station for DMRS pattern type 1 and type 2 are comprehensively described.

[0731] Figure 31 The operation of the base station and UE according to this embodiment is shown. In the first step, the base station configures DMRS pattern Type 1 and Type 2 information via a higher layer in step 3100. Next, if DMRS pattern Type 1 is configured in step 3110, the process moves to step 3105 and the base station can signal information regarding the number of layers and port numbers used for Type 1, as described in <Example 2-7>. Furthermore, as described in <Example 2-6>, DMRS power boosting can be configured differently depending on the number of configured layers.

[0732] Next, in step 3120, it is determined whether the DMRS is configured as a one-symbol pattern or a two-symbol pattern. If the DMRS is configured as a one-symbol pattern, then in step 3125, DMRS parameters for one symbol are configured, as described in <Example 2-5>. If the DMRS is configured as a two-symbol pattern, then in step 3130, the base station configures DMRS parameters for two symbols, as described in <Example 2-5>. Thereafter, in step 3135, the UE identifies the information configured for the DMRS, and in step 3160, performs channel estimation.

[0733] If the DMRS pattern is configured as Type 2 in step 3110, the same operations as those in the case of configuring the DMRS pattern as Type 1 can be performed. As proposed in <Example 2-5>, the DMRS density can vary depending on the DMRS port mapping, and depending on the DMRS type, different antenna port mapping methods can be used depending on whether the DMRS includes one or two symbols. Specifically, in the case of Type 1, the parameter configurations in steps 3125 and 3130 can be different. In the case of Type 2, the parameter configurations in steps 3145 and 3150 can be different.

[0734] More specifically, if the Type 1 mode is applied in consideration of DMRS overhead and channel estimation performance, then when the DMRS includes one symbol, mode 2810 may be preferred. Furthermore, in the case of the Type 1 mode, if the DMRS includes two symbols, modes 2850 or 2860 may be preferred. In the case of Type 1, as described in <Embodiment 2-5>, the parameter configurations in steps 3125 and 3130 may be different.

[0735] Unlike the above, if the Type 2 mode is applied in consideration of DMRS overhead and channel estimation performance, then when the DMRS includes one symbol, mode 2910 may be preferred. Furthermore, in the case of the Type 2 mode, if the DMRS includes two symbols, mode 2930 or 294 may be preferred. In the case of Type 2, the parameter configuration in steps 3145 and 3150 may be the same as described in <Embodiment 2-5>.

[0736] In order to implement the above-mentioned embodiments of the present disclosure, Figure 32 and Figure 33 The transmitter, receiver, and processor of each of the UE and the base station are shown in [2-1]. The method of configuring the DMRS structure, the method of generating the DMRS sequence by the base station, and the transmission / reception method of the base station and the UE are described in [2-8]. Each of the receiver, processor, and transmitter of the base station should operate according to each embodiment to perform the method.

[0737] Figure 32 1 is a block diagram showing the internal structure of a UE according to an embodiment of the present disclosure. Figure 32 As shown, the UE of the present disclosure may include a UE receiver 3200, a UE transmitter 3204, and a UE processor 3202. In embodiments of the present disclosure, the UE receiver 3200 and the UE transmitter 3204 are generally referred to as a transceiver. The transceiver can transmit and receive signals to and from a base station. The signals may include control information and data. To this end, the transceiver includes: an RF transmitter that up-converts and amplifies the frequency of the transmitted signal; an RF receiver that performs low-noise amplification and down-converts the frequency of the received signal. In addition, the transceiver can receive signals via a radio channel, output the signals to the UE processor 3202, and transmit the signals output from the UE processor 3202 via the radio channel. The UE processor 3202 can control a series of processes to enable the UE to operate according to the above-described embodiments of the present disclosure. For example, the UE receiver 3200 can receive a reference signal from the base station, and the UE processor 3202 can perform control to analyze a reference signal application method. In addition, the UE transmitter 3204 can transmit the reference signal.

[0738] Figure 331 is a block diagram showing the internal structure of a base station according to an embodiment of the present disclosure. Figure 33 As shown, a base station according to the present disclosure may include a base station receiver 3301, a base station transmitter 3305, and a base station processor 3303. In the embodiments of the present disclosure, the base station receiver 3301 and the base station transmitter 3305 are generally referred to as a transceiver. The transceiver can transmit and receive signals to and from a UE. The signals may include control information and data. To this end, the transceiver includes: an RF transmitter that up-converts and amplifies the frequency of the transmitted signal; an RF receiver that performs low-noise amplification and down-converts the frequency of the received signal. Furthermore, the transceiver can receive signals via a radio channel, output the signals to the base station processor 3303, and transmit signals output from the base station processor 3303 via the radio channel. The base station processor 3303 can control a series of processes to enable the base station to operate according to the above-described embodiments of the present disclosure. For example, the base station processor 3303 can determine the structure of a reference signal and perform control to generate configuration information for the reference signal to be transmitted to the UE. Furthermore, the base station can generate a DMRS sequence based on the information. Thereafter, the base station transmitter 3305 may send the reference signal and configuration information to the UE, and the base station receiver 3301 may receive the reference signal.

[0739] <Third embodiment>

[0740] The transmission of an aperiodic channel state information reference signal (CSI-RS) can be used to reduce the increased CSI-RS transmission overhead in order to support the transmission of UE-specific beamforming CSI-RS, multiple transmit and receive points (TRPs), or multiple panels. Meanwhile, in LTE systems, aperiodic CSI-RS is supported only for broadband transmission. However, in NR systems, it is necessary to support narrowband (subband) aperiodic CSI-RS to support various UE bandwidths and use resources efficiently. To this end, the present disclosure provides a method and apparatus for determining the bandwidth used for transmission and the measurement of aperiodic CSI-RS in a wireless communication system.

[0741] <Example 3-1>

[0742] Hereinafter, the present disclosure relates to a method for transmitting / receiving channel state information in a wireless mobile communication system using a multi-carrier application multiple access scheme (such as Orthogonal Frequency Division Multiple Access (OFDMA)), by which a UE measures a radio channel state (channel quality) and informs a base station of the measurement result.

[0743] In the detailed description of the embodiments of the present disclosure, an OFDM-based wireless communication system (especially the 3GPP EUTRA standard) will be mainly described, but in other communication systems with similar technical backgrounds and channel forms, the main subject matter of the present disclosure may be slightly modified without departing from the scope of the present disclosure.

[0744] Figure 34 The FD-MIMO system to which the embodiment of the present disclosure is applied is shown. The FD-MIMO system introduced in LTE-A Pro is evolved from the conventional LTE and LTE-A MIMO technologies and can use multiple transmit antennas greater than or equal to 8 antennas. Figure 34 In the example, eNB transmitting device 3400 transmits wireless signals to eight or more transmitting antennas. As indicated by reference numeral 3410, multiple transmitting antennas can be arranged to maintain a minimum distance between them. For example, the minimum distance can be half the wavelength of the wireless signal. Generally, if a distance corresponding to half the wavelength of the wireless signal is maintained between transmitting antennas, the signal transmitted from each transmitting antenna is affected by a wireless channel with low correlation. If the bandwidth of the transmitted wireless signal is 2 GHz, the distance can be 7.5 cm. As the frequency band increases above 2 GHz, the distance decreases.

[0745] exist Figure 34 In the example, eight or more transmit antennas deployed in the eNB transmit device 3400 can be used to transmit signals to one or more UEs, as indicated by reference numeral 3420. Appropriate precoding is applied to the multiple transmit antennas, and the signals are simultaneously transmitted to multiple UEs. In this case, a single UE can receive one or more of the information streams. Generally, the number of information streams a UE can receive is determined by the number of receive antennas occupied by the UE and the channel conditions.

[0746] Figure 35 Radio resources corresponding to one subframe and one resource block (RB), which are minimum units that can be scheduled to downlink, in LTE and LTE-A systems are shown. Figure 35 The radio resource shown consists of one subframe on the time axis and one RB on the frequency axis. The radio resource includes 12 subcarriers in the frequency region and 14 OFDM symbols in the time region, and therefore has a total of 168 natural frequency and time positions. In LTE and LTE-A, Figure 35 Each of the natural frequency and time positions in may be referred to as a resource element (RE).

[0747] exist Figure 35 In the radio resources shown, the following multiple different types of signals can be sent.

[0748] 1. Cell-specific RS (CRS) 3500: refers to a reference signal that is periodically transmitted to all UEs belonging to a cell and can be commonly used by multiple UEs.

[0749] 2. Demodulation Reference Signal (DMRS) 3510: This is a reference signal sent for a specific UE and is only sent when data is sent to the corresponding UE. DMRS may include a total of 8 DMRS ports. In LTE-A, ports 7 to 14 correspond to DMRS ports, and each port maintains orthogonality to prevent interference through code division multiplexing (CDM) or frequency division multiplexing (FDM).

[0750] 3. Physical Downlink Shared Channel (PDSCH) 3520 : refers to a data channel transmitted to a downlink, and is used when a base station transmits traffic to a UE and is transmitted using REs through which a reference signal is not transmitted in a data region 3560 .

[0751] 4. Channel State Information Reference Signal (CSI-RS) 3540: refers to a reference signal sent to a UE belonging to a cell and is used to measure the channel state. Multiple CSI-RSs can be sent in a cell. In the LTE-A system, one CSI-RS can correspond to one, two, four, or eight antenna ports (APs) (or used interchangeably with ports). In the LTE-A Pro system, one CSI-RS can correspond to one, two, four, eight, twelve, or sixteen antenna ports, and can be expanded to a maximum of thirty antenna ports in the future.

[0752] 5. Other channels (Physical Hybrid ARQ Indicator Channel (PHICH), Physical Control Format Indicator Channel (PCFICH), and Physical Downlink Control Channel (PDCCH)) 3530: These channels are used to provide control information required by the UE to receive the PDSCH or to transmit ACK / NACK for HARQ operations for uplink data transmission. Control channels are transmitted in the control region 3550.

[0753] In addition to the above signals, in order to allow the UE to receive the CSI-RS sent by another base station in the corresponding cell, muting can be set in the LTE-A and LTE-A Pro systems. Muting can be applied to the location where the CSI-RS can be sent, and generally, the UE can skip the corresponding radio resources and receive the service signal. In the LTE-A and LTE-A Pro systems, muting can be referred to as zero-power CSI-RS as a different term. This is because muting is applied equally to the location of the CSI-RS, and no transmission power is sent due to the muting characteristics.

[0754] exist Figure 35In FIG, CSI-RS may be transmitted using some positions marked with A, B, C, D, E, F, G, H, I, and J according to the number of antennas used to transmit CSI-RS. In addition, muting may also be applied to some positions marked with A, B, C, D, E, F, G, H, I, and J. Specifically, CSI-RS may be transmitted using two, four, or eight REs according to the number of transmit antenna ports. Figure 35 In the IEEE 802.11ac standard, if the number of antenna ports is 2, the CSI-RS is transmitted to half of a specific pattern; if the number of antenna ports is 4, the CSI-RS is transmitted to the entire specific pattern; and if the number of antenna ports is 8, the RS is transmitted using two patterns. In contrast, muting is always performed in units of one pattern. That is, when the position does not overlap with the CSI-RS, muting can be applied to multiple patterns, not to only some of a single pattern. However, muting can be applied to only part of a pattern only when the CSI-RS position and muting overlap.

[0755] As described above, in LTE-A, two, four, or eight antenna ports can be configured in one CSI-RS resource. If CSI-RS for two antenna ports is transmitted, the signal for each antenna port is transmitted in two consecutive REs on the time axis, and the signals for the antenna ports can be distinguished by orthogonal codes. Furthermore, if CSI-RS for four antenna ports is transmitted, in addition to the CSI-RS for two antenna ports, the signals for the remaining two antenna ports are transmitted in the same manner as described above using two additional REs. In the same manner, CSI-RS for eight antenna ports can be transmitted.

[0756] The base station can increase the CSI-RS transmission power to improve channel estimation accuracy. If four or eight antenna port CSI-RS are transmitted, a specific CSI-RS port can only be transmitted in the CSI-RS RE at a predetermined position and cannot be transmitted in another OFDM symbol in the same OFDM symbol. Figure 36 FIG. 4 shows an example of CSI-RS RE mapping for the nth and n+1th PRBs when the base station transmits CSI-RS for eight antenna ports. Figure 36 As shown in FIG. 1 , if the CSI-RS RE position for the 15th or 16th AP is as indicated by reference numeral 3600 (second subcarrier), no transmission power is used in the CSI-RS REs 3610 (third, eighth, and ninth subcarriers) for the remaining 17th to 22nd APs, as in the 15th or 16th AP. Therefore, in the second subcarrier, the 15th or 16th AP can use the transmission power to be used in the third, eighth, and ninth subcarriers.

[0757] Natural power boosting can be configured so that the power of the 15th CSI-RS port transmitted over the second subcarrier is a maximum of 6 dB higher than the transmission power used in the data RE 3620. The current 2nd / 4th / 8th / port CSI-RS pattern can perform natural power boosting of 0 / 2 / 6 dB, and each AP can transmit CSI-RS with full power utilization.

[0758] In addition, the UE can receive the allocation of CSI-IM (or interference measurement resources (IMR)) together with the CSI-RS, and the CSI-IM resource has the same structure and position as the CSI-RS supporting 4 ports. The CSI-IM corresponds to a resource for accurately measuring interference from a neighboring base station by receiving data from one or more base stations by the UE. If the base station expects to measure the amount of interference when the neighboring base station transmits data and the amount of interference when the neighboring base station does not transmit data, the base station can configure the CSI-RS and two CSI-IM resources to effectively measure the amount of interference from the neighboring base station by allowing the neighboring base station to always transmit a signal in one CSI-IM and allowing the neighboring base station not to always transmit a signal in the other CSI-IM.

[0759] In LTE-A and LTE-A Pro systems, the base station can notify the UE of CSI-RS resource configuration information (or CSI-RS resource configuration) through high-layer signaling. The CSI-RS resource configuration information includes the index of the CSI-RS configuration information, the number of ports included in the CSI-RS, the transmission period of the CSI-RS, the transmission offset, the CSI0RS configuration information (CSI-RS configuration), the CSI-RS scrambling ID, and the quasi-co-location (QCL) information. Specifically, the UE can determine the RE in which the CSI-RS is transmitted by combining the CSI-RS configuration information and the information about the number of ports included in the CSI-RS.

[0760] In LTE-A and LTE-A Pro systems, a base station transmits a reference signal to a UE to measure the downlink channel state, and the UE measures the channel state between the base station and the UE using the CRS or CSI-RS transmitted by the base station. Several factors must be considered in conjunction with the channel state, and the amount of downlink interference may be one of these factors. The amount of downlink interference may include interference signals generated by antennas belonging to neighboring base stations, thermal noise, and the like, which is important when the UE determines the downlink channel state.

[0761] For example, if a base station with one transmit antenna transmits a signal to a UE with one receive antenna, the UE can determine the energy per symbol (receivable via the downlink) based on the reference signal received from the base station and the amount of interference received simultaneously in the interval in which the corresponding symbol is received, and can determine Es / Io (ratio of energy per symbol to interference). The determined Es / Io is converted into a data transmission rate or a value corresponding thereto and transmitted to the base station in the form of a channel quality indicator (CQI), so that the base station can determine the data transmission rate at which the base station performs downlink transmission to the UE.

[0762] In LTE-A and LTE-A Pro systems, the UE sends feedback to the base station regarding downlink channel status information, allowing the base station to use the received information for scheduling. Specifically, the UE measures the reference signal transmitted by the base station via the downlink and sends feedback of the extracted information to the base station in a format defined by the LTE / LTE-A standards. In LTE and LTE-A systems, the information fed back by the UE primarily includes the following three types of information:

[0763] Rank Indicator (RI): The number of spatial layers that the UE can receive under the current channel state

[0764] ● Precoder Matrix Indicator (PMI): An indicator of the precoding matrix preferred by the UE under the current channel state

[0765] ● Channel Quality Indicator (CQI): The maximum data rate that the UE can perform reception under the current channel state. The CQI can be replaced by SINR, maximum error correction code rate, modulation scheme, data efficiency per frequency, etc., which can be used similarly to the maximum data rate.

[0766] RI, PMI and CQI are interrelated. For example, the precoding matrices supported by LTE and LTE-A systems are defined differently for each rank. Therefore, even if the PMI value when RI is 1 and the PMI value when RI is 2 are the same as each other, they are interpreted differently. In addition, when the UE determines the CQI, the UE assumes that the rank value and PMI value provided by the UE to the base station are applied to the base station. That is, if the UE provides RI_X, PMI_Y and CQI_Z to the base station, it means that when the rank is RI_X and the precoding is PMI_Y, the UE can perform reception at a data transmission rate corresponding to CQI_Z. As described above, when the UE calculates the CQI, the UE considers which transmission scheme is used for the base station, and therefore, obtains optimal performance when the corresponding transmission scheme is used to perform actual transmission.

[0767] RI, PMI, and CQI can be fed back periodically or aperiodically. If the base station expects to obtain aperiodic feedback information for a specific UE, the base station may configure an aperiodic feedback indicator included in the downlink control information (DCI) for uplink data scheduling of the corresponding UE to perform specific aperiodic feedback and perform uplink data scheduling of the corresponding UE. If the UE receives an indicator configured to perform aperiodic feedback in the nth subframe, the UE performs uplink transmission by inserting the aperiodic feedback information into the data transmission in the n+kth subframe. Here, k is 4 in frequency division duplex (FDD) and is defined as shown in [Table 41] in time division duplex (TDD).

[0768] [Table 41]

[0769]

[0770] In order to generate and report channel information, a base station with a large number of antennas is required to configure reference signal resources for measuring channels of 8 or more antennas and send these reference signal resources to the UE. To this end, in the LTE-A Pro system, two, four, eight, twelve, or sixteen antenna ports can be configured in one CSI-RS resource, and the function of configuring 20, 22, 28, and 32 antenna ports may be added in the future. Specifically, in LTE-A Pro Release 13, two types of CSI-RS configuration methods are provided.

[0771] In the first method, the base station configures one or more 4-port or 8-port CSI-RS patterns in the UE through non-precoded (NP) CSI-RS (CSI-RS for reporting Class A channel state information (CSI)), and combines the combinations of the configured CSI-RS patterns to allow the UE to receive CSI-RS according to 8 or more CSI-RS ports. Specifically, {1, 2, 4, 8} port CSI-RS follows the traditional mapping rule. In the case of 12-port CSI-RS, an aggregation of three 4-port CSI-RS patterns will be configured, while in the case of 16-port CSI-RS, an aggregation of two 8-port CSI-RS patterns can be configured. In addition, in LTE-A version 13, for 12 / 16-port CSI-RS, an orthogonal cover code (OCC) with a length of 2 or 4 is used to support code division multiplexing (CDM)-2 or CDM-4.

[0772] Figure 36The description is about CDM-2-based CSI-RS power boosting, and according to the description, a maximum power boost of 9dB is required compared to PDSCH for full power utilization of CDM-2-based 12 / 16-port CSI-RS. This means that for full power utilization in CDM-2-based 12 / 16-port CSI-RS operation, higher-performance hardware is required. In LTE-A Pro Release 13, CDM-4-based 12 / 16-port CSI-RS was introduced to take this into account. In this case, full power utilization can be achieved with the same 6dB power boost as the traditional power boost.

[0773] In the second method, the base station can apply a specific beam to multiple transceiver units (TXRUs) through beamformed (BF) CSI-RS (CSI-RS for reporting Class B CSI) to allow the UE to identify multiple TXRUs as one CSI-RS port. If the base station knows the UE channel information in advance, the base station can configure only some of the CSI-RSs for which it applies a beam suitable for the channel information in its own TXRU. In another example, the base station can configure multiple CSI-RS resources including 8 or fewer CSI-RS ports in the UE. At this time, the base station can apply different beam directions for each CSI-RS resource configuration to beamform the CSI-RS port.

[0774] Figure 37 An example of BF CSI-RS operation is shown. Figure 37 , the base station 3710 can configure three CSI-RSs 3720, 3730, and 3740 beamformed in different directions in the UEs 3750 and 3760. Each of the CSI-RS resources 3720, 3730, and 3740 may include one or more CSI-RS ports. The UE 3750 may generate channel state information for the configured CSI-RS resources 3720, 3730, and 3740, and report the index of the UE's preferred CSI-RS resource among the CSI-RS resources to the base station through a CSI-RS resource indicator (CRI). Figure 37 In the example of , if UE 3750 prefers CSI-RS resource 3730, the UE may report the index corresponding to CSI-RS resource 3730 to the base station. If UE 3760 prefers CSI-RS resource 3720, the UE may report the index corresponding to CSI-RS resource 3720 to the base station.

[0775] Based on LTE-A Pro Release 13, CRI supports reporting on one CSI-RS index that is most preferred by the UE, but in the future it can be extended to a combination of CSI-RS indices preferred by the UE. For example, if the two CSI-RS resources most preferred by UE 3750 are CSI-RS resources 3730 and 3740, UE 3750 can directly report the two indices of the corresponding CSI-RS resources or report an index indicating a set of corresponding CSI-RS resources. This allows various applications by supporting UEs with wide channel angle extension or high mobility with beams in various directions, or supporting the selection of multiple CSI-RSs sent in different transmit and receive points (TRPs).

[0776] <Example 3-2>

[0777] <Example 3-2> proposes a method for configuring aperiodic CSI-RS. Up to LTE-A Pro Release 13, as described in <Example 3-1>, the detailed configuration values ​​of the CSI-RS are semi-statically determined via higher-layer signaling (or RRC signaling). CSI-RS resource configuration information up to LTE-A Pro Release 13 includes the following information.

[0778] - Number of CSI-RS ports: indicates the number of CSI-RS ports included in one CSI-RS resource.

[0779] - CSI-RS configuration: indicates the configuration value indicating the location of CSI-RS REs along with the number of CSI-RS ports.

[0780] -CSI-RS subframe configuration, I CSI-RS : Indicates the configuration value, which indicates the CSI-RS transmission period, T CSI-RS , CSI-RS subframe offset and Δ CSI-RS .

[0781] -CSI-RS power boost factor, P C : The ratio of the assumed UE's CSI-RS transmission power to PDSCH.

[0782] -Scrambled ID, n ID .

[0783] - Quasi-co-localization (QCL) information

[0784] The conventional CSI-RS is periodically transmitted, including the number of ports determined according to a specific configuration value. Therefore, if UE-specific beamforming is applied to the beamformed CSI-RS, CSI-RS resource configurations corresponding to the number of UEs are required, which may be a significant burden. Alternatively, if cell-specific beamforming is applied to the beamformed CSI-RS, the number of antennas of the base station also increases, and therefore, if the beamwidth becomes narrower, many CSI-RS resource configurations are also required.

[0785] To address this issue and enable efficient CSI-RS resource allocation, aperiodic CSI-RS (Ap-CSI-RS) transmission can be introduced. From a UE's perspective, aperiodic CSI-RS is not always transmitted in all configured resources, but only in resources that meet specific conditions.

[0786] Figure 38 An example of CSI-RS transmission / reception and CSI reporting based thereon is shown. Figure 38 As indicated by reference numeral 3800, the base station can configure CSI-RS resources for aperiodic CSI-RS transmission in each UE. In this case, considering that information indicating aperiodic CSI-RS is not always transmitted, the base station can configure the same aperiodic CSI-RS resources in multiple UEs. This improves the efficiency of CSI-RS resource usage by operating an aperiodic CSI-RS resource pool shared among a predetermined number of UEs.

[0787] As indicated by reference numeral 3810, the base station may trigger aperiodic CSI reporting to the UE based on CSI-RS configuration information through L1 signaling such as UL grant. The UE may perform the following operations based on aperiodic CSI triggering and according to the aperiodic CSI-RS configuration method.

[0788] 1. A method of receiving an aperiodic CSI-RS transmitted in the same subframe as a subframe in which an aperiodic CSI trigger is transmitted.

[0789] 2. A method of receiving an aperiodic CSI-RS transmitted in a subframe closest to a subframe in which an aperiodic CSI trigger is signaled.

[0790] 3. A method of receiving an aperiodic CSI-RS transmitted in a subframe closest to a subframe after a subframe in which an aperiodic CSI trigger is signaled.

[0791] 4. Method for receiving the aperiodic CSI-RS transmitted after a predetermined time from the subframe in which the in-use signal transmits the aperiodic CSI trigger (e.g., after the l-th subframe, where l can be configured to be less than the above k). In addition, l can be a predetermined value or a value specified by higher layer signaling or L1 signaling.

[0792] After that, the UE can generate CSI based on the received aperiodic CSI-RS, and as described above, report the CSI to the base station in the n + k-th subframe as indicated by reference numerals 3820 and 3830. Here, the n-th subframe is the subframe including the aperiodic CSI trigger. If the UE follows the method of "4. Method for receiving the aperiodic CSI-RS transmitted after a predetermined time from the subframe in which the in-use signal transmits the aperiodic CSI trigger (e.g., after the l-th subframe, where l can be configured to be less than the above k)", the CSI generated by the UE can be reported to the base station in the n + k + 1-th subframe. This is to ensure the UE processing time for CSI generation.

[0793] The detailed method for operating the aperiodic CSI-RS resource pool is described below.

[0794] 1. Method using RRC signaling + L1 signaling

[0795] 2. Method using RRC signaling + MAC CE signaling + L1 signaling

[0796] 3. Method using RRC signaling + MAC CE signaling

[0797] In terms of reliability, RRC signaling, MAC CE signaling, and L1 signaling have higher reliability in the order of RRC > MAC CE > L1; and in terms of latency, they require latency time in the order of L1 < MAC CE < RRC. For example, when the UE receives the information, the information configured by RRC signaling has high reliability but a long reception time, while the information configured by L1 signaling has a very short latency time required for reception but low reliability. In addition, due to the transmission of restricted DCI, L1 signaling has the disadvantage of high signaling cost.

[0798] As described in the first example, if the method of 1. RRC signaling + L1 signaling is used, the base station can configure N CSI-RS resources in the UE through RRC signaling, and then select L (< N) resources from the N configured CSI-RS resources through L1 signaling. At this time, since the L1 signaling overhead is determined by N and L (N combination L, NCL), if N = 8 CSI-RS resources are configured through RRC and L ≤ 2 resources are selected through L1 signaling, a very large DCI payload corresponding to a total of bits may be required.

[0799] At the same time, as described in the second example, if the method of 2.RRC signaling+MAC CE signaling+L1 signaling is used, a specific CSI-RS resource specified by MAC CE signaling among the CSI-RS resources of RRC signaling can be activated or deactivated, and L1 signaling can be performed for it. Therefore, the base station can obtain an appropriate trade-off between the CSI-RS resource configuration delay time and the DCI signaling overhead. For example, if N=8 CSI-RS resources are configured through RRC, K=4 resources among the N=8 CSI-RS resources are activated through MAC CE, and then L≤2 resources are selected through L1 signaling. It should be noted that the required DCI payload can be reduced to a total of 100 Mbps compared to the first example. Bit.

[0800] As described in the third example, if the 3.RRC signaling + MAC CE signaling method is used, the K CSI-RS resources specified by MAC CE signaling among the N CSI-RS resources in the RRC signaling can be activated or deactivated. In this case, unlike the first and second examples, the UE ultimately determines whether to transmit the CSI-RS via MAC CE without L1 signaling. In this case, it is not possible to indicate aperiodic CSI-RS transmission for each subframe, but there is an advantage of significantly reducing DCI overhead.

[0801] In this embodiment, the aperiodic CSI-RS can be configured through high-layer signaling. The CSI-RS resource configuration information for the aperiodic CSI-RS may include detailed configuration information, such as the number of CSI-RS ports, CSI-RS configuration, CSI-RS subframe configuration, CSI-RS power boost index, scrambling ID, and quasi-co-location (QCL) information as described above. If the CSI-RS resource configuration information for the aperiodic CSI-RS is included in the CSI-RS subframe in the detailed configuration information, the "2. Method of receiving the aperiodic CSI-RS sent in the subframe closest to the subframe triggering the aperiodic CSI with a signal" or "3. Method of receiving the aperiodic CSI-RS sent in the subframe closest to the subframe after the subframe triggering the aperiodic CSI with a signal" of the aforementioned aperiodic CSI-RS reception method can be used. This is because the CSI-RS subframe configuration includes information about candidate subframes in which the aperiodic CSI-RS can be sent.

[0802] Meanwhile, if the CSI-RS resource configuration information for the aperiodic CSI-RS does not include the CSI-RS subframe configuration among the detailed configuration information, or if the CSI-RS resource configuration information includes the CSI-RS subframe configuration but specifies (or is instructed by the base station) to ignore it, then the CSI-RS resource configuration information may not include information about candidate subframes in which the aperiodic CSI-RS can be transmitted. Therefore, among the aforementioned aperiodic CSI-RS reception methods, "1. A method of receiving an aperiodic CSI-RS transmitted in the same subframe as the subframe in which the aperiodic CSI trigger is transmitted." or "4. A method of receiving an aperiodic CSI-RS transmitted after a predetermined time (e.g., after the first subframe) from the subframe in which the aperiodic CSI trigger is signaled" can be used.

[0803] In L1 signaling (UL, DCI or UL grant), there may be an aperiodic CSI-RS trigger including 1 or more bits. If 1-bit aperiodic CSI-RS triggering is supported by L1 signaling, the method of analyzing the CSI request field of DCI format 0 or DCI format 4 may vary depending on whether the triggering is performed. The DCI format is only an example, and a DCI format for uplink grant such as DCI format 0 or 4 may correspond thereto. For example, if the aperiodic CSI-RS is not triggered, the CSI request field can be used to indicate a set of service cells configured by higher layer signaling to report CSI, a set of CSI processes, or a set of CSI subframes, as in the prior art. On the other hand, if the aperiodic CSI-RS is triggered, the CSI request field can be used to indicate a CSI-RS resource for transmitting the aperiodic CSI-RS among multiple CSI-RS resource candidates, as shown in [Table 42]. At this time, since aperiodic CSI-RS transmission is triggered by an additional 1-bit L1 signaling, all code points in the CSI request field may have other meanings other than "not triggering aperiodic CSI-RS and aperiodic CSI".

[0804] In another example, if 1-bit aperiodic CSI-RS triggering is supported, a method for analyzing the CSI request field of DCI format 1 or DCI format 4 can be indicated through higher-layer signaling (RRC signaling). In this case, the CSI request field can be used to indicate a set of serving cells, a set of CSI processes, or a set of CSI subframes for reporting CSI, configured through higher-layer signaling, as in the prior art, or to indicate a CSI-RS resource for transmitting aperiodic CSI-RS among multiple CSI-RS resource candidates, as described in the example of [Table 43]. In this case, since the CSI request field should include a function for triggering aperiodic CSI-RS, at least one codepoint may have a meaning indicating "not triggering aperiodic CSI-RS and aperiodic CSI."

[0805] [Table 42]

[0806]

[0807] [Table 43]

[0808]

[0809]

[0810] On the other hand, the aperiodic CSI-RS trigger including multiple bits may include a function of indicating which CSI-RS resources are used to transmit the aperiodic CSI-RS. [Table 44] shows an example of an aperiodic CSI-RS trigger field including two bits. According to the example of [Table 44], at least one code point in the aperiodic CSI-RS trigger field may have a meaning indicating "not triggering aperiodic CSI-RS and aperiodic CSI". The other three code points mean aperiodic CSI-RS triggering (01) in serving cell c, and aperiodic CSI-RS triggering (10, 11) for the first and second CSI-RS sets for multiple serving cells (cross-serving cells) high layer signaling. At this time, the CSI-RS is associated with different aperiodic CSI-RS and aperiodic CSI reports. Even if the aperiodic CSI trigger field includes three or more bits, it can be extended based on a principle similar to [Table 44]. A new table such as Table

[44] can be specified by a new transmission mode (TM), for example, TM 11.

[0811] [Table 44]

[0812]

[0813] <Example 3-3>

[0814] This embodiment describes an example of dynamic port numbering configuration in a method for configuring aperiodic CSI-RS. Dynamic port numbering means that when transmitting aperiodic CSI-RS, the number of CSI-RS ports included in an aperiodic CSI-RS resource can vary. For example, this means that aperiodic CSI-RS resources can be configured through dynamic CSI-RS resource aggregation.

[0815] Figure 39 An example of a dynamic port numbering operation scenario for aperiodic CSI-RS is shown. Figure 39 , it is assumed that each of base stations 3900 and 3905 operates eight CSI-RS ports.

[0816] For example, if UE 3910 receives data from base station 3900, base station 3900 may transmit an aperiodic CSI-RS in subframe 3915 and trigger aperiodic CSI through L1 signaling. UE 3910 may receive the aperiodic CSI-RS transmitted in aperiodic CSI-RS resource 3925 using a method similar to that described in Example 3-2, generate CSI for channel 3920 including an 8-port CSI-RS, and report the CSI to the base station.

[0817] In another example, if UE 3910 receives data from base stations 3900 and 3905 simultaneously (for example, as in CoMPJT), the base station may transmit an aperiodic CSI-RS in subframe 3930 through L1 signaling and trigger aperiodic CSI. In this case, aperiodic CSI-RS triggering may mean simultaneously transmitting an aperiodic CSI-RS resource 3940 for measuring a channel 3935 and an aperiodic CSI-RS resource 3950 for measuring a channel 3945. Although for ease of description, Figure 29 The case where CSI-RS resources 3940 and 3950 are configured in different subframes is shown, but the present disclosure is not limited thereto, and CSI-RS resources may be transmitted in the same subframe according to the aperiodic CSI-RS triggering method in <Example 3-2>.

[0818] The UE can receive aperiodic CSI-RS 3940 and 3950, and generate and report CSI based on an 8-port CSI-RS for each CSI-RS resource (using an 8Tx codebook), but can identify CSI-RS 3940 and 3950 as one CSI-RS resource (aggregation between aperiodic CSI-RS resources), and generate and report CSI based on a 16-port CSI-RS (using a 16Tx codebook). This allows the UE to generate PMI using a codebook greater than the number of antennas, and the generated PMI includes not only the phase between base station antennas, but also implicitly includes the phase difference between TRP 3900 and TRP 3905, making it possible to resolve the CQI mismatch problem in coordinated multi-point (CoMP) joint transmission (JT).

[0819] Figure 40 Another example of a dynamic port numbering operation scenario for aperiodic CSI-RS is shown. In the future, CSI may be extended to include functionality for indicating multiple preferred CSI-RS sources or a subset of multiple CSI-RS resources. If the total number of CSI-RS ports of the CSI-RS resources included in a subset is different, different precoding schemes may need to be applied depending on the selected CSI-RS resource subset.

[0820] For example, assuming that Figure 40 The "one cell" operation scenario shown. At this time, the macro base station 4000 sends coverage RS (CRS, coverage CSI-RS or cell-specific CSI-RS), but can send UE-specific RS 4030, 4040, 4050 or 4060 (CSI-RS, UE-specific CSI-RS or dedicated CSI-RS) in different TRPs. That is, the corresponding TRPs can be distinguished by the UE-specific RS. When it is assumed that each TRP has multiple UE-specific RS resources to which different beams are applied, the UE can report the preferred UE-specific RS resource information for each TRP to the base station through the CRI. For example, when it is assumed that the UE receives data in multiple TRPs, if data is received in TRPs 4010 and 4020, the UE can report a preferred CSI-RS among CSI-RS 4030 and 4040 for TRP 4010 and a preferred CSI-RS among CSI-RS 4050 and 4060 for TRP 4020. In this case, the base station can selectively transmit aperiodic CSI-RS in multiple CSI-RS resources with reference to the UE preference. As described above, if aperiodic CSI-RS is transmitted in multiple CSI-RS resources, the detailed configuration and transmission method can be similar to Figure 39 .

[0821] Specifically, for aperiodic CSI-RS configuration based on dynamic port configuration or dynamic resource aggregation, the following methods may be considered.

[0822] ●Aperiodic CSI-RS configuration method 1

[0823] The first method is to configure the aperiodic CSI-RS through high-layer signaling and 1-bit L1 signaling. In this example, the CSI-RS resource configuration information of the high-layer signaling for the aperiodic CSI-RS is as follows: Figure 41 shown.

[0824] Figure 41 An example of CSI-RS resource configuration information is shown. Figure 41 , three types of high-layer signaling can be performed considering CSI-RS types such as non-precoded CSI-RS, beamformed CSI-RS, and hybrid CSI-RS. At this time, as described in <Example 3-2>, the high-layer signaling can include RRC signaling and MAC CE signaling. This means Figure 41 K in A , K B , K CA or K CB The indicated CSI-RS resources or configuration may only depend on the RRC configuration, but can be activated or deactivated by MAC CE configuration. Figure 41 The RRC configuration is mainly shown, but similar to the description of <Embodiment 3-2>, it can be extended to the aggregation of RRC and MAC CE, so its detailed description will be omitted.

[0825] In the case of non-precoded CSI-RS, the higher layer signaling may include signaling information 4120. Specifically, the signaling information 4120 includes a number of CSI-RS ports for configuring more than or equal to 8 CSI-RS ports. KA CSI-RS configuration 4130, and another detailed configuration information 4140. At this time, if the aperiodic CSI-RS is triggered by 1-bit L1 signaling, this may mean that the aperiodic CSI-RS is transmitted in all CSI-RS REs designated by reference numeral 4130.

[0826] In the case of beamformed CSI-RS, the higher layer signaling may include signaling information 4150. Specifically, the signaling information 4150 may include K B CSI-RS resource configuration information may be provided, and the CSI-RS resource configuration information 4160 may include CSI-RS detailed configuration information. At this time, if aperiodic CSI-RS is triggered by 1-bit L1 signaling, the following two methods may be considered.

[0827] The first method is to send aperiodic CSI-RS in all CSI-RS REs specified by reference numeral 4160. In this case, CRI can be reported through aperiodic CSI-RS, but the effect of reducing CSI-RS overhead may be weakened due to the aperiodic CSI-RS. The second method is to send aperiodic CSI-RS only in the CSI-RS resources specified by the CRI reported by the UE in information 4160. In this case, the effect of reducing CSI-RS overhead can be maximized, but it is difficult to perform CRI reporting through aperiodic CSI-RS. In the second method, if the CRI specifies multiple CSI-RS resources, the specified CSI-RS resource can be identified as a single CSI-RS resource. For example, if the CRI specifies two 8-port CSI-RS resources as aperiodic CSI-RS resources, the number of aperiodic CSI-RS ports assumed by the UE is the sum of the number of CSI-RS ports included in the two CSI-RS resources, that is, 16.

[0828] In the case of hybrid CSI-RS, the high-layer signaling may include signaling information 4170. Specifically, the signaling information 4170 may include two parts, such as a K portion including a K portion for configuring multiple CSI-RS ports. CA The portion 4180 of the CSI-RS configuration includes different beams K to which different CB For example, part 4180 may be similar to reference numeral 4120, and part 4190 may be similar to reference numeral 4150. At this time, if aperiodic CSI-RS is triggered by 1-bit L1 signaling, the following two methods may be considered.

[0829] The first method is to transmit aperiodic CSI-RS in all CSI-RS REs designated by reference numeral 4180. In this case, the CSI-RS port designated by reference numeral 4190 is transmitted as a periodic CSI-RS resource. The second method is to transmit aperiodic CSI-RS only in all CSI-RS REs designated by reference numeral 4190 or in a portion designated by CRI among all CSI-RS resources designated by reference numeral 4190. In the case of mixed CSI-RS, aperiodic CSI-RS triggering by 2-bit L1 signaling can be supported. For example, the corresponding bit can be used to indicate whether to transmit aperiodic CSI-RS in the CSI-RS resource designated by reference numeral 4180, and to indicate whether to transmit aperiodic CSI-RS in the CSI-RS resource designated by reference numeral 4190.

[0830] In this example, if L1 signaling for aperiodic CSI-RS triggering is applied to "all CSI-RS resources," L1 signaling can be supported individually for each CSI process. Alternatively, if L1 signaling for aperiodic CSI-RS triggering is applied to "CSI-RS resources specified by CRI," L1 signaling can be applied to the corresponding CSI-RS resources regardless of the CSI process.

[0831] ●Aperiodic CSI-RS configuration method 2

[0832] The second method corresponds to the aperiodic CSI-RS configuration by high-layer signaling and L1 signaling including multiple bits. In this example, the CSI-RS resource configuration information for the aperiodic CSI-RS high-layer signaling is as follows: Figure 42 shown.

[0833] Figure 42 Another example of CSI-RS resource configuration information is shown. In addition to configuration 4220, Figure 42 Configuration and Figure 41 The configuration is the same or similar, so Figure 42 Can be cited Figure 41 At this time, the high-level signaling may include RRC signaling and MAC CE signaling, as described in <Example 3-2>. This means Figure 42 K in A , K B , K CA or K CB The indicated CSI-RS resources or configuration may only depend on the RRC configuration, but can be activated or deactivated by MAC configuration. Figure 42 In the embodiment 3-2, the RRC configuration is mainly described, but it can be extended to the aggregation of RRC and MAC CE as in <Embodiment 3-2>, so its detailed description will be omitted.

[0834] refer to Figure 42, three types of high-layer signaling may be performed considering non-precoded CSI-RS, beamformed CSI-RS, and hybrid CSI-RS. In this example, a CSI-RS resource subset may be specified to transmit aperiodic CSI-RS through L1 signaling, and the CSI-RS resource subset may be notified to the UE through high-layer signaling, as shown in reference numeral 4220. In reference numeral 4220, one or more CSI-RS resources may be allocated to set A to set X, and if two or more CSI-RS resources are allocated to one set, the allocated CSI-RS resources may be identified as a single CSI-RS resource. For example, if set A is designated as an aperiodic CSI-RS resource through L1 signaling, the number of aperiodic CSI-RS ports assumed by the UE is the sum of the number of CSI-RS ports included in all CSI-RS resources belonging to set A. In <Example 3-2>, activation and deactivation through MAC CE signaling is one of the detailed examples for configuring a CSI-RS resource subset. If only RRC and MAC CE configurations are provided and L1 signaling is not supported as in the third example of <Embodiment 3-2>, the UE may assume that all CSI-RSs belonging to set A to set X of the CSI-RS resource subset are transmitted.

[0835] In the case of non-precoded CSI-RS, as in aperiodic CSI-RS configuration method 1, the higher layer signaling may include signaling information 4120. Specifically, the signaling information 4120 includes a number of CSI-RS ports for configuring more than or equal to 8 CSI-RS ports. KA CSI-RS configuration configuration 4130, and another detailed configuration information 4140. At this time, if the aperiodic CSI-RS is triggered by L1 signaling containing multiple bits, it may mean that some configuration information of information 4120 is ignored, the ignored information is replaced by the CSI-RS resource configuration information specified by reference numeral 4220, and the aperiodic CSI-RS is sent in the corresponding RE. For example, if the aperiodic CSI-RS is triggered by 2-bit L1 signaling, the aperiodic CSI-RS can be sent with reference to the above [Table 42], [Table 43] or [Table 44] or the following [Table 45]. The purpose of [Table 42] to [Table 44] is as described above. In the case of [Table 45], if the base station is configured as "00", the UE can use CRI to perform reporting without aggregating the CSI-RS resources for sending the aperiodic CSI-RS. In another method, it can be achieved by including K A Whether to send aperiodic CSI-RS for CSI-RS configuration 4130 is signaled by L1 signaling of the bit.

[0836] [Table 45]

[0837]

[0838] In the case of beamformed CSI-RS, as in the aperiodic CSI-RS configuration method 1, the higher layer signaling may include signaling information 4150. Specifically, the signaling information 4150 may include K to which different beams may be applied. B CSI-RS resource configuration information may be provided, and the CSI-RS resource configuration information 4160 may include CSI-RS detailed configuration information. At this time, if the aperiodic CSI-RS is triggered by 1-bit L1 signaling including multiple bits, the following two methods may be considered.

[0839] The first method is to include K B In the embodiment of the present invention, the L1 signaling of the bit is used to signal whether to transmit aperiodic CSI-RS for each CSI-RS resource configuration information 4160. This is the most flexible method, but requires a higher L1 signaling overhead. The second method is to receive aperiodic CSI-RS configuration information through L1 signaling reference configuration information 4220 including a smaller number of bits in order to reduce L1 signaling overhead. For example, the aperiodic CSI request field can be used as aperiodic CSI-RS configuration information based on [Table 42], [Table 43], or [Table 44], or a new table such as [Table 45] can be introduced. Since its detailed description is similar to the above example, it will be omitted.

[0840] In the case of hybrid CSI-RS, as in aperiodic CSI-RS configuration method 1, the higher layer signaling may include signaling information 4170. Specifically, the signaling information 4170 may include two parts, such as a K including a K for configuring multiple CSI-RS ports. CA The portion 4180 of the CSI-RS configuration includes different beams K to which different CB For example, part 4180 may be similar to reference numeral 4120, and part 4190 may be similar to reference numeral 4150. At this time, if aperiodic CSI-RS is triggered by 1-bit L1 signaling including multiple bits, the following two methods may be considered.

[0841] The first method is to include K CA +K CB or 1+K CB The L1 signaling of the 1+K bit is used to signal whether to transmit aperiodic CSI-RS for each CSI-RS resource configuration information 4170. If the L1 signaling includes 1+K CBbits, the CSI-RS configuration included in part 4180 can determine whether to send the aperiodic CSI-RS as a group. This is the most flexible method, but requires a higher L1 signaling overhead. The second method is to receive aperiodic CSI-RS configuration information through L1 signaling reference configuration information 4220 including a smaller number of bits in order to reduce L1 signaling overhead. For example, the aperiodic CSI request field can be used as aperiodic CSI-RS configuration information based on [Table 42], [Table 43], or [Table 44], or a new table such as [Table 45] can be introduced. Since its detailed description is similar to the above example, it will be omitted.

[0842] ●Aperiodic CSI-RS configuration method 3

[0843] The third method corresponds to the aperiodic CSI-RS configuration by the high-layer signaling and L1 signaling including a plurality of bits. In this example, the CSI-RS resource configuration information of the high-layer signaling for the aperiodic CSI-RS is as follows: Figure 41 At this time, the high-level signaling may include RRC signaling and MAC CE signaling as described in <Example 3-2>. This means Figure 41 K in A , K B , K CA or K CB The indicated CSI-RS resources or configuration may only depend on the RRC configuration, but can be activated or deactivated by MAC configuration. Figure 41 The RRC configuration is mainly described, but as in <Embodiment 3-2>, it can be extended to the aggregation of RRC and MACCE, so its detailed description will be omitted.

[0844] refer to Figure 41 , three types of high-layer signaling can be performed considering CSI-RS types such as non-precoded CSI-RS, beamformed CSI-RS, and hybrid CSI-RS. In this example, similar to the aperiodic CSI-RS configuration method 1, 1-bit or 2-bit L1 signaling can be used to trigger the aperiodic CSI-RS. The difference between the example and the aperiodic CSI-RS configuration method 1 will be described. In this example, it is possible to reconfigure the "number of CSI-RS ports" in the detailed configuration information of the aperiodic CSI-RS, and therefore, conventional L1 signaling such as the CSI request field can be reused as shown in the following [Table 46] or [Table 47], or new L1 signaling can be introduced as shown in the following [Table 48] or [Table 49].

[0845] [Table 46] is a table indicating the method by which the UE analyzes the CSI request field when the aperiodic CSI-RS is triggered by 1-bit L1 signaling. Similar to the aperiodic CSI-RS configuration method 1, the UE can assume that the aperiodic CSI-RS is transmitted in the CSI-RS resource for non-precoded CSI-RS, the aperiodic CSI-RS is transmitted in the CSI-RS resource corresponding to the most recently reported CSI among the CSI-RS resources for beamforming CSI-RS, or the aperiodic CSI-RS is transmitted in the CSI-RS resource for UE-specific beamforming CSI-RS (in this case, one resource is configured in the UE). The UE can identify the CSI-RS configuration in each CSI-RS resource configuration information according to the condition.

[0846] The UE can then determine how many CSI-RS ports are transmitted in the corresponding CSI-RS resource based on the 1-bit CSI request field value used to trigger the aperiodic CSI-RS trigger configured by the base station. For example, if the CSI request field is 00, the number of CSI-RS ports can be 1; if the CSI request field is 01, the number of CSI-RS ports can be 2; if the CSI request field is 10, the number of CSI-RS ports can be 4; and if the CSI request field is 11, the number of CSI-RS ports can be 8. The UE can then analyze the RE positions on which the aperiodic CSI-RS is transmitted by combining the CSI-RS configuration and the number of CSI-RS ports. This method of analyzing the CSI request field is an example, and various other numbers can be signaled by RRC. For example, if the CSI request field is 00, the number of CSI-RS ports signaled by RRC when inserted into the traditional CSI-RS resource configuration is reused. Otherwise, if the CSI request field is 01, the number of CSI-RS ports may be analyzed as 1; if the CSI request field is 10, the number of CSI-RS ports may be analyzed as 2; and if the CSI request field is 11, the number of CSI-RS ports may be analyzed as 4.

[0847] [Table 46]

[0848]

[0849] [Table 47] is a table indicating the method by which the UE analyzes the CSI request field when the CSI request field is configured to trigger aperiodic CSI-RS through 1-bit RRC signaling. Similar to aperiodic CSI-RS configuration method 1, the CSI request field can be configured to trigger aperiodic CSI-RS through 1-bit RRC signaling, and the UE can assume that the aperiodic CSI-RS is transmitted in the CSI-RS resource for non-precoded CSI-RS, the aperiodic CSI-RS is transmitted in the CSI-RS resource corresponding to the most recently reported CSI among the CSI-RS resources for beamforming CSI-RS, or the aperiodic CSI-RS is transmitted in the CSI-RS resource for UE-specific beamforming CSI-RS (in this case, one resource is configured in the UE).

[0850] The UE can identify the CSI-RS configuration in each CSI-RS resource configuration information according to the conditions. Thereafter, the UE can know whether the non-periodic CSI-RS is sent in the corresponding CSI-RS resource through the CSI request field value configured by the base station, and if the non-periodic CSI-RS is sent, it knows how many CSI-RS ports are sent. For example, if the CSI request field is 00, it means that no non-periodic CSI-RS is sent. If the CSI request field is 01, the number of CSI-RS ports can be analyzed as 1; if the CSI request field is 10, the number of CSI-RS ports can be analyzed as 2; and if the CSI request field is 11, the number of CSI-RS ports can be analyzed as 4. Thereafter, by combining the CSI-RS configuration and the number of CSI-RS ports, the UE can analyze the RE position on which the non-periodic CSI-RS is sent.

[0851] The method of analyzing the CSI request field is an example, and specific values ​​may be defined in the table, but various numbers may be RRC signaled. For example, if the CSI request field is 00, it means that no aperiodic CSI-RS is transmitted. If the CSI request field is 01, the number of CSI-RS ports signaled by RRC when inserted into the legacy CSI-RS resource configuration information is reused. If the CSI request field is 10, the number of CSI-RS ports may be analyzed as 1; and if the CSI request field is 11, the number of CSI-RS ports may be analyzed as 2.

[0852] [Table 47]

[0853]

[0854] In another method, the number of CSI-RS ports included in the aperiodic CSI-RS resource may be notified through additional L1 signaling. [Table 48] and [Table 49] are tables indicating examples of configuring the number of aperiodic CSI-RS ports through L1 signaling. Similar to aperiodic CSI-RS configuration method 1, the UE may assume that the aperiodic CSI-RS is transmitted in the CSI-RS resource for non-precoded CSI-RS, the aperiodic CSI-RS is transmitted in the CSI-RS resource corresponding to the most recently reported CSI among the CSI-RS resources for beamforming CSI-RS, or the aperiodic CSI-RS is transmitted in the CSI-RS resource for UE-specific beamforming CSI-RS (in this case, one resource is configured in the UE). At this time, the UE may identify the CSI-RS configuration in each CSI-RS resource configuration information according to the condition.

[0855] Afterwards, when aperiodic CSI-RS is triggered, the UE can know how many CSI-RS ports are transmitted in the corresponding aperiodic CSI-RS resource based on the aperiodic CSI-RS field value shown in [Table 48] or [Table 49]. In the example of [Table 48], the number of CSI-RS ports based on the aperiodic CSI-RS field value can be pre-determined by the aperiodic CSI-RS field table. For example, if the CSI request field is 00, the number of CSI-RS ports is analyzed as 1; if the CSI request field is 01, the number of CSI-RS ports is analyzed as 2; if the CSI request field is 10, the number of CSI-RS ports is analyzed as 4; and if the CSI request field is 11, the number of CSI-RS ports is analyzed as 8. Thereafter, the UE can analyze the RE position on which the aperiodic CSI-RS is transmitted by combining the CSI-RS configuration and the number of CSI-RS ports.

[0856] The method of analyzing the non-periodic CSI-RS field is an example, and a specific number may be defined as shown in [Table 48], but various numbers may be signaled by RRC as shown in [Table 49]. For example, if the CSI request field is 00, the number of CSI-RS ports signaled by RRC when inserted into the legacy CSI-RS resource configuration information is reused. If the CSI request field is 01, the number of CSI-RS ports may be analyzed as 1; if the CSI request field is 10, the number of CSI-RS ports may be analyzed as 2; and if the CSI request field is 11, the number of CSI-RS ports may be analyzed as 4.

[0857] Similar to the examples in Tables 48 and 49, considering the coexistence of periodic CSI-RS and aperiodic CSI-RS, the following Table 50 can be used. Table 50 enables or disables periodic CSI-RS-based aperiodic CSI reporting and aperiodic CSI-RS-based aperiodic CSI reporting, respectively.

[0858] [Table 48]

[0859]

[0860] [Table 49]

[0861]

[0862]

[0863] [Table 50]

[0864]

[0865] <Example 3-4>

[0866] <Example 3-4> describes a rate mapping method based on non-periodic CSI-RS transmission. In LTE-A and LTE-APro systems, the UE can identify non-zero power (NZP) CSI-RS configuration information and zero power (ZP) CSI-RS configuration information to identify PDSCH RE mapping and perform rate matching. In traditional CSI-RS transmission, CSI-RS transmission information is semi-statically configured, so no additional signaling is required for rate matching. However, if the non-periodic CSI-RS transmission proposed in the present disclosure is introduced, whether to perform CSI-RS transmission and some CSI-RS configuration information can be dynamically changed, and therefore a method for effective rate matching is required. This embodiment provides the following three methods as rate matching methods considering non-periodic CSI-RS.

[0867] ●Aperiodic CSI-RS rate matching method 1

[0868] The first method is a method of performing rate matching based on the CSI-RS resource configuration information and ZP CSI-RS configuration of RRC signaling. As described in the embodiment, as a method of non-periodic CSI-RS transmission, the traditional CSI-RS subframe specified by the CSI-RS resource configuration information is considered to be a non-periodic CSI-RS resource pool, and the subframe in which the actual non-periodic CSI-RS is transmitted is notified to the UE through L1 signaling such as UL authorization. The first method is a method of performing rate matching under the assumption that the UE believes that CSI-RS subframes other than the CSI-RS subframes allocated to the UE itself are allocated to other UEs. If the first method is used, the rate matching mechanism is simple, but if the number of UEs is small, the data transmission efficiency may be reduced more than necessary.

[0869] ●Aperiodic CSI-RS rate matching method 2

[0870] The second method is a method of performing rate matching based on CSI-RS resource configuration information of RRC signaling, ZP CSI-RS configuration, aperiodic CSI-RS triggering of L1 signaling, and CSI request field. If aperiodic CSI-RS is triggered under the assumption that whether to perform aperiodic CSI-RS triggering is determined by 1-bit L1 signaling, the UE can interpret the aperiodic CSI-RS configuration information according to [Table 42] to [Table 50] as described above.

[0871] At the same time, even if aperiodic CSI-RS is not triggered, the UE can interpret the aperiodic CSI-RS configuration information according to [Table 42] to [Table 50] and identify the corresponding CSI-RS resource as an aperiodic ZP CSI-RS or an aperiodic interference measurement resource (IMR). This will perform rate matching aperiodically depending on whether aperiodic CSI-RS transmission is performed. If there is currently no aperiodic CSI-RS for the corresponding UE, it is possible to provide information on whether there is an aperiodic CSI-RS for another UE, and if there is an aperiodic CSI-RS, the RE in which the aperiodic CSI-RS exists is provided by this method.

[0872] According to this example, the method for analyzing the CSI request field or the aperiodic CSI field does not need to be the same when the aperiodic CSI-RS is triggered and when it is not triggered. For example, if the aperiodic CSI-RS is triggered, the method follows [Table 42]; and if the aperiodic CSI-RS is not triggered, the method follows [Table 50]. This is because if the aperiodic CSI-RS is triggered, there is no need to notify the UE that the aperiodic CSI-RS does not exist; however, if the aperiodic CSI-RS is not triggered, it is necessary to notify the other UE and the corresponding UE that the aperiodic CSI-RS does not exist.

[0873] ●Aperiodic CSI-RS rate matching method 3

[0874] The third method is a method of performing rate matching based on the CSI-RS resource configuration information, ZP CSI-RS configuration, aperiodic CSI-RS triggering, and CSI request field of RRC signaling. It is assumed that whether to use the CSI request field for aperiodic CSI-RS triggering or the aperiodic CSI-RS field is determined by 1-bit RRC signaling, and for convenience of description, it is also assumed that both the CSI request field and the aperiodic CSI-RS field are signaled to the UE. At this time, if the aperiodic CSI-RS field is as shown in [Table 50], when the CSI request field has a value other than 00, that is, when aperiodic CSI is triggered, the aperiodic CSI-RS field can be interpreted as aperiodic NZP CSI-RS resource information. On the other hand, when the CSI request field is 00, that is, when aperiodic CSI is not triggered, the aperiodic CSI RS field can be interpreted as aperiodic ZP CSI-RS resource or aperiodic IMR information. In other words, by comprehensively interpreting the CSI request field and the aperiodic CSI-RS field, it is possible to support dynamic rate matching not only for the NZP CSI-RS but also for the ZP CSI-RS.

[0875] <Examples 3-5>

[0876] <Example 3-5> proposes a method for configuring aperiodic CSI-RS transmission bandwidth. In the above embodiments, a method for configuring resources for aperiodic CSI-RS transmission in one or more CSI-RS resources and a method for determining transmission timing have been described. At the same time, in order to maximize the efficiency of aperiodic CSI-RS transmission efficiency, it is very important to manage the aperiodic CSI-RS transmission bandwidth. For example, in the LTE system, the UE determines the channel bandwidth that the corresponding UE should support based on the E-UTRA band supported by the UE. Referring to [Table 51] below, if the UE supports E-UTRA band 2, the UE should support a channel bandwidth of {1.4, 3, 5, 10, 15, 20} MHz; and if the UE supports E-UTRA band 6, the UE should support a channel bandwidth of {5, 10} MHz. That is, the LTE system does not separately support a UE-specific maximum bandwidth, and the channel bandwidth may vary depending on the service of MTC, eMTC or NB-IoT.

[0877] [Table 51]

[0878]

[0879] On the other hand, due to various factors, such as the coexistence of various vertical technologies such as eMBB, URLLC, and mMTC within the same frequency band, as well as low-cost eMBB UEs, the NR system can support different UE bandwidths for each UE. Therefore, UEs with different maximum UE bandwidths can coexist within a wide system bandwidth, and supporting all of these UEs with wideband aperiodic CSI-RS may waste resources. To address this issue, this embodiment provides a method for managing the aperiodic CSI-RS transmission bandwidth.

[0880] In the NR system, the RRC configuration for CSI-RS may include timing information such as the CSI-RS transmission period and time offset. The time offset may include one or more values ​​of the slot offset for periodic CSI-RS or semi-persistent CSI-RS and the trigger offset for aperiodic CSI-RS. The trigger offset includes information about the time difference between the triggering of aperiodic CSI-RS transmission by DCI and the actual transmission. In aperiodic CSI-RS transmission, timing information may be ignored. For example, in the case of aperiodic CSI-RS, the UE may ignore the transmission period and offset value, and may identify whether aperiodic CSI-RS transmission is performed by the DCI reception timing including the aperiodic CSI-RS transmission information.

[0881] In addition, in the NR system, the RRC configuration for CSI-RS may include transmission band information such as CSI-RS transmission bandwidth, frequency offset, and RB or subband position. The frequency offset may be an offset in units of PRBs based on a PRB including a downlink or uplink DC subcarrier or based on a scheduled PDSCH, or may be an offset in units of subbands including multiple PRBs. As described above, the CSI-RS transmission band information configured by RRC is suitable for semi-static management of the CSI-RS transmission band, but dynamic changes in the CSI-RS transmission band are not possible. For dynamic CSI-RS transmission band configuration and change, the following methods may be considered.

[0882] The first method is to dynamically change the CSI-RS transmission band through CSI-RS frequency hopping. The base station and the UE can share a predetermined frequency hopping pattern and determine the position of the frequency resource of the CSI-RS transmitted in the narrow frequency band (subband) according to specific rules, LI (DCI) or L2 (MAC CE or RRC) signaling. The hopping timing can be defined as an absolute value by the time slot or subframe position, or as a relative value by the DCI including the aperiodic CSI-RS trigger. For example, if the hopping timing is defined as an absolute value, the subband position for CSI-RS transmission can depend on the time slot or subframe index change, regardless of the aperiodic CSI-RS trigger. On the other hand, if the hopping timing is defined as a relative value, the subband position for CSI-RS transmission depends on the aperiodic CSI-RS trigger and changes. In the present disclosure, the subband for CSI-RS transmission can be determined by controlling the hopping pattern type and the transmission timing, but once the hopping pattern is determined, it takes a lot of time to change the hopping pattern, and therefore, the freedom of subband configuration is limited.

[0883] The second method is subband / wideband transmission indication via L1 (DCI) or MAC CE signaling or subband / wideband switching signaling. The method disclosed herein supports dynamic signaling (L1 or MACECE) for changing CSI-RS transmission band information configured via RRC.

[0884] Figure 43 An example of the second method for configuring and changing the CSI-RS transmission band is shown. Figure 43In the UE, DCI is transmitted in the common search space (CSS), or the UE-specific search space (USS) defined in the control resource sets (CORESETs) 4305, 4320, 4330, and 4340 configured in the UE can indicate whether to transmit aperiodic CSI-RS 4315, 4325, 4335, and 4345, as well as the frequency and / or time resource index. In addition, the DCI also includes transmission band change signaling, which indicates whether the corresponding aperiodic CSI-RS is transmitted in subband 4315 or 4325 or wideband 4335 or 4345. These two types of information can be jointly encoded, but for the convenience of description, it is assumed that the two types of information are encoded independently.

[0885] If the transmission band change signaling means subband transmission, the corresponding aperiodic CSI-RS transmission band is the same as the bandwidth of the CORESET indicated by reference numeral 4315, or the corresponding aperiodic CSI-RS transmission band is the same as the configured PDSCH transmission band 4310 as indicated by reference numeral 4325. If the transmission band change signaling means wideband transmission, the corresponding aperiodic CSI-RS transmission band is the same as the CSI-RS transmission band configured by the RRC indicated by reference numeral 4335, or the corresponding aperiodic CSI-RS transmission band is the same as the system bandwidth, or if the system bandwidth is divided into a plurality of bandwidth parts, the aperiodic CSI-RS transmission band is the same as the band corresponding to the bandwidth part indicated by reference numeral 4345.

[0886] Similarly, transmission band change signaling can be used as an indicator to indicate whether to use the CSI-RS transmission band configured through RRC or to perform wideband CSI-RS transmission corresponding to the system bandwidth, bandwidth part, or UE bandwidth.

[0887] Figure 44 The figure shows a process of performing bandwidth adaptation of the UE through transmission band change signaling. The base station can schedule PDSCH 4410 within the UE bandwidth 4412 through the DI sent in the CORESET 4405 and trigger aperiodic CSI-RS 4415. At this time, the base station can instruct the UE to use the CSI-RS transmission band configured by RRC via transmission band change signaling (configured to 0). In the reference numeral 4415, it is assumed that the CSI-RS transmission band configured by RRC is the same as the CORESET band.

[0888] Meanwhile, if the base station desires to allocate the PDSCH of the UE to a wider frequency band indicated by reference numeral 4440, the base station may require CSI for a frequency band wider than the frequency band 4415. Therefore, the base station configures and transmits a frequency band change signal (1) so that the UE receives a wideband aperiodic CSI-RS 4425 through the DCI transmitted in the CORESET 4420. The UE can receive the CSI-RS 4425, generate CSI, and then report the generated CSI to the base station, and the base station can perform scheduling based on the CSI. Based on the scheduling result, the base station can allocate and transmit a wideband PDSCH 4440 to the UE through the DCI transmitted to the UE in the CORESET 4430.

[0889] Similarly, the transmission band change signaling can be used as an indicator that indicates whether to use the CSI-RS transmission band configured by RRC or whether to match the most recently configured downlink bandwidth with the CSI-RS transmission band. Figure 43 and Figure 44 Similar, so it is omitted.

[0890] Although the specification and drawings illustrate and describe a UE having a single CORESET, this is for convenience of description only, and the description can be expanded and applied to a case where the UE has multiple CORESETs. In the above description, the CORESET can be replaced with a UE bandwidth or bandwidth portion configured separately from the control channel, and the same method can be applied thereto. Since its detailed description is similar to the example, it will be omitted.

[0891] This description and the accompanying drawings are examples of a case where aperiodic CSI-RS is transmitted in a single resource, and correspond to a method of supporting aperiodic CSI-RS transmission band change by signaling with a small payload (1 bit is used in the simplest example). At the same time, if aperiodic CSI-RS is transmitted in multiple resources, the example can be extended by the following two methods. The first method is to apply the same transmission band change signaling to multiple CSI-RS resources. In this case, there is no additional DCI payload increase, but the freedom of CSI-RS transmission band configuration is reduced. The second method will support CSI-RS resource-specific or resource group-specific transmission band change signaling. In this case, the DCI payload increases according to the number of aperiodic CSI-RS resources transmitted simultaneously, but the freedom of CSI-RS transmission band configuration increases. If the second method is applied, the number of aperiodic CSI-RS resources transmitted simultaneously will be limited to 2 or 3.

[0892] Although the description and drawings describe and illustrate that DCI including aperiodic CSI-RS triggering and transmission band change signaling and the corresponding aperiodic CSI-RS are transmitted in the same time slot, this is only for convenience of description, and it is obvious that they can be transmitted in one or more time slots according to the CSI-RS transmission timing information.

[0893] <Examples 3-6>

[0894] <Embodiment 3-6> provides a method for configuring an aperiodic CSI-RS transmission band to obtain CSI of a control channel. In this case, the transmission band change signaling can be understood as control channel CSI triggering signaling.

[0895] Figure 45 The process of controlling the non-periodic CSI-RS transmission and reception bands through control channel CSI trigger signaling is shown. The base station can schedule PDSCH 4505 in the UE bandwidth 4515 through the DCI sent in CORESET 4510 and trigger the non-periodic CSI-RS 4520. At this time, the base station can instruct the UE to use the CSI-RS transmission band configured by RRC via the control channel CSI trigger signaling (configured as 0). This is to generate CSI for PDSCH by the UE, and the UE generates the required CSI, such as CQI, PMI, RI and CRI, taking into account the transmission environment of PDSCH (channel coding using low-density parity check code (LDPC), {4-1024} modulation order and PDSCH transport block size (TBS)). In the reference numeral 4520, it is assumed that the CSI-RS transmission band configured by RRC is the same as the band for scheduling PDSCH.

[0896] Meanwhile, if the base station requires CSI for the control channel, the base station configures control channel CSI trigger signaling (to 1) so that the UE receives CSI-RSs 4530 and 4540 to generate control channel CSI using the DCI transmitted in CORESET 4525. Configuring control channel CSI trigger signaling so that the UE receives CSI-RSs 4530 and 4540 for generating control channel CSI may mean changing the actual CSI-RS transmission band, as indicated by reference numeral 4530, but only changing the UE's reception window (as indicated by reference numeral 4545) without changing the actual CSI-RS transmission band (as indicated by reference numeral 4540). The UE then receives CSI-RSs 4530 or 4545, generates CSI for the PDCCH, and generates the required CSI, such as CQI, PMI, RI, and CRI, taking into account the transmission environment for the PDCCH (channel coding using polarization codes, 4-QAM modulation order, and PDCCH payload size). The base station can perform scheduling on the PDSCH and PDCCH through it.

[0897] Although the specification and drawings illustrate and describe a UE having a single CORESET, this is for convenience of description only, and the description can be expanded and applied to a case where the UE has multiple CORESETs. In the above description, the CORESET can be replaced with a UE bandwidth or bandwidth portion configured separately from the control channel, and the same method can be applied thereto. Since its detailed description is similar to the example, it will be omitted.

[0898] This description and the accompanying drawings are examples of a case where aperiodic CSI-RS is transmitted in a single resource, and correspond to a method of supporting aperiodic CSI-RS transmission band change by signaling with a small payload (1 bit is used in the simplest example). At the same time, if aperiodic CSI-RS is transmitted in multiple resources, the example can be extended by the following two methods. The first method is to apply the same transmission band change signaling to multiple CSI-RS resources. In this case, there is no additional DCI payload increase, but the freedom of CSI-RS transmission band configuration is reduced. The second method will support CSI-RS resource-specific or resource group-specific transmission band change signaling. In this case, the DCI payload increases according to the number of aperiodic CSI-RS resources transmitted simultaneously, but the freedom of CSI-RS transmission band configuration increases. If the second method is applied, the number of aperiodic CSI-RS resources transmitted simultaneously will be limited to 2 or 3.

[0899] Although the description and drawings describe and illustrate that DCI including non-periodic CSI-RS triggering and transmission band change signaling and the corresponding non-periodic CSI-RS are sent in the same time slot, this is only for convenience of description, and it is obvious that they can be sent in one or more time slots according to the CSI-RS timing information.

[0900] <Examples 3-7>

[0901] <Example 3-5> and <Example 3-6> mainly describe the control of the transmission band for NZP CSI-RS. Meanwhile, ZP CSI-RS plays various roles, such as clearing the CSI-RS resource portion from another cell (or beam or TRP) to perform PDSCH rate matching, measuring interference from another cell (or beam or TRP), or performing NZP CSI-RS power boosting, and therefore, handling the control of the ZP CSI-RS transmission band can be important. <Example 3-7> proposes a method for controlling the ZP CSI-RS transmission band.

[0902] Figure 46 The process of controlling the transmission and reception bands of the aperiodic ZP CSI-RS is shown. The base station can schedule the PDSCH 4605 within the UE bandwidth 4615 through the DCI transmitted in the CORESET 4610 and trigger the aperiodic CSI-RS 4620. It is assumed that the aperiodic CSI-RS transmission band is configured to be the same as the CORESET transmission band of the corresponding UE. At the same time, the UE's PDSCH 4640 may overlap with other sub-band period CSI-RS resources 4625 that the UE does not receive (not transmitted from the serving cell or TRP). In this case, the CORESET of the UE that receives the aperiodic CSI-RS 4525 may be transmitted in a frequency band different from the frequency band in which the CORESET 4605 is transmitted, and therefore, the transmission frequency band 4625 may also be different from the frequency band 4660.

[0903] Considering this situation, the following two methods can be used to configure the ZP CSI-RS to correspond to reference numeral 4625. The first method is to manage the ZP CSI-RS transmission band by separately supporting transmission band change signaling for the NZP CSI-RS and transmission band change signaling for the ZP CSI-RS. For example, if the ZP CSI-RS transmission band configured by RRC is insufficient to cover reference numeral 4625, the base station can configure a wideband region represented as the system bandwidth, bandwidth part, or bandwidth for scheduling PDSCH, as indicated by reference numeral 4630, instead of the ZP CSI-RS transmission band configured by RRC via ZP CSI-RS transmission band change signaling. This increases the overhead of the ZP CSI-RS to some extent, but has the advantage of preventing a significant increase in the transmission band change signaling overhead. In another example of the first method, if the ZP CSI-RS transmission band configured by RRC is insufficient to cover reference numeral 4625, the base station may directly insert the ZP CSI-RS transmission band information into the ZP CSI-RS transmission band change signaling. In this case, the ZP CSI-RS transmission band configuration 4635 may be the same as or similar to the NP CSI-RS transmission band configuration 4625, and thus, the ZP CSI-RS configuration overhead may be optimized, but the transmission band change signaling overhead may be greatly increased.

[0904] The second method uses the same transmission band change signaling for both NZP CSI-RS and ZP CSI-RS. In this case, the transmission band change signaling can be jointly encoded with one or all of the aperiodic NZP CSI-RS triggering signaling, the aperiodic ZP CSI-RS triggering signaling, and the resource selection signaling, or encoded independently from the aperiodic NZP CSI-RS triggering signaling, the aperiodic ZP CSI-RS triggering signaling, and the resource selection signaling. If the aperiodic NZP CSI-RS triggering signaling, the resource selection signaling, and the transmission band change signaling are jointly encoded, the aperiodic ZP CSI-RS bandwidth can be determined based on the most recently configured aperiodic NZP CSI-RS transmission bandwidth signaling. If the aperiodic NZP CSI-RS triggering signaling, the ZP CSI-RS triggering signaling, the resource selection signaling, and the transmission band change signaling are jointly encoded, the aperiodic ZP CSI-RS bandwidth is determined based on the joint encoding method. If aperiodic NZP CSI-RS triggering signaling, ZP CSI-RS triggering signaling, resource selection signaling, and transmission band change signaling are independently encoded, the aperiodic ZP and NZP CSI-RS bandwidths can be independently determined according to the encoded transmission band change signaling.

[0905] Although the specification and drawings illustrate and describe a UE having a single CORESET, this is for convenience of description only, and the description can be expanded and applied to a case where the UE has multiple CORESETs. In the above description, the CORESET can be replaced with a UE bandwidth or bandwidth portion configured separately from the control channel, and the same method can be applied thereto. Since its detailed description is similar to the example, it will be omitted.

[0906] This description and the accompanying drawings are examples of a case where aperiodic CSI-RS is transmitted in a single resource, and correspond to a method of supporting aperiodic CSI-RS transmission band change by signaling with a small payload (1 bit is used in the simplest example). At the same time, if aperiodic CSI-RS is transmitted in multiple resources, the example can be extended by the following two methods. The first method is to apply the same transmission band change signaling to multiple CSI-RS resources. In this case, there is no additional DCI payload increase, but the freedom of CSI-RS transmission band configuration is reduced. The second method will support CSI-RS resource-specific or resource group-specific transmission band change signaling. In this case, the DCI payload increases according to the number of aperiodic CSI-RS resources transmitted simultaneously, but the freedom of CSI-RS transmission band configuration increases. If the second method is applied, the number of aperiodic CSI-RS resources transmitted simultaneously will be limited to 2 or 3.

[0907] Although the description and drawings describe and illustrate that DCI including non-periodic CSI-RS triggering and transmission band change signaling and the corresponding non-periodic CSI-RS are sent in the same time slot, this is only for convenience of description, and it is obvious that they can be sent in one or more time slots according to the CSI-RS timing information.

[0908] The examples in [Table 45] to [Table 50] may have different meanings depending on the definition of "higher layer". For example, if the higher layer only means RRC signaling, the table may mean a list of CSI-RSs for RRC signaling. If the higher layer also means MACCE signaling, the table may mean CSI-RS resources activated by MAC CE. Similarly, it is obvious that the meaning of CSI-RS resources indicated by L1 signaling can be changed. For example, if the higher layer only means RRC signaling, the CSI-RS resources indicated by L1 signaling may mean a list of CSI-RSs for RRC signaling. If the higher layer also means MAC CE signaling, the CSI-RS resources indicated by L1 signaling may mean CSI-RS resources activated by MAC CE.

[0909] If an aperiodic CSI-RS is transmitted according to an embodiment of the present disclosure, reference will be made to Figure 47 To describe the operation of the base station. Figure 47 FIG illustrates the operation of a base station for transmitting an aperiodic CSI-RS. Figure 47 In step 4700, the base station configures at least one aperiodic CSI-RS through RRC signaling. At this time, the RRC signaling may include the transmission band information of the aperiodic CSI-RS. Thereafter, if necessary, in step 4710, according to the embodiment proposed in the present disclosure, the base station may configure the resources to be activated or deactivated among the CSI-RS configured by RRC through the higher layer (including MAC CE). In addition, the base station may trigger the aperiodic CSI-RS through L1 signaling in step 4720, and may indicate the change in the transmission band configured by RRC. Thereafter, in step 4730, the base station sends the aperiodic CSI-RS with the aperiodic CSI-RS resources notified in steps 4700, 4710 and 4720.

[0910] According to the embodiments of the present disclosure, reference will be made to Figure 48 The operation of a UE based on aperiodic CSI-RS is described. Figure 48 FIG2 shows the operation of the UE for receiving the aperiodic CSI-RS. Figure 48 In step 4800, the UE receives semi-static configuration information related to the aperiodic CSI-RS through higher layer (RRC) signaling. Thereafter, if necessary, according to the embodiment proposed by the present invention, in step 4810, the UE receives configuration information of resources to be activated or deactivated among the CSI-RS configured by RRC through higher layer (including MAC CE) signaling. In addition, in step 4820, the UE receives dynamic configuration information including transmission band change signaling related to the aperiodic CSI-RS through L1 signaling. Thereafter, based on the aperiodic CSI-RS configuration information received in steps 4800, 4810 and 4820, the UE receives the aperiodic CSI-RS in the corresponding CSI-RS resource. Subsequently, the UE generates CSI information based on the aperiodic CSI-RS received in step 4830, and reports the CSI information to the base station at a predetermined timing.

[0911] Figure 49 is a block diagram illustrating an internal structure of a UE according to an embodiment of the present disclosure.

[0912] refer to Figure 49 , the UE includes a communication unit 4901 and a controller 4902. The communication unit 4901 performs the function of sending data to the outside (e.g., a base station) or receiving data from the outside. Here, the communication unit 4901 can send feedback information to the base station under the control of the controller 4902.

[0913] Controller 4902 controls the status and operation of all elements in the UE. Specifically, controller 4902 generates feedback information based on information assigned by the base station. In addition, controller 4902 can control communication unit 4901 to feed back generated channel information to the base station based on timing information assigned by the base station. To this end, controller 4902 may include channel estimator 4903.

[0914] The channel estimator 4903 may determine required feedback information through the CSI-RS and feedback allocation information received from the base station, and estimate the channel using the received CSI-RS based on the feedback information.

[0915] although Figure 49 The example in which the UE includes the transceiver 4901 and the controller 4902 has been described, but the UE is not limited thereto and may further include various elements based on the functions performed in the UE. For example, the UE may further include: a display for displaying the current state of the UE; an input unit for receiving a user input signal to execute a function; and a storage unit for storing generated data in the UE.

[0916] In addition, the channel estimator 4903 is shown to be included in the controller 4902, but is not limited thereto. The controller 4902 may control the transceiver 4901 to receive configuration information associated with each of at least one reference signal resource from the base station. In addition, the controller 4902 may measure at least one reference signal and control the transceiver 4901 to receive feedback configuration information from the base station for generating feedback information based on the measurement result.

[0917] The controller 4902 may measure at least one reference signal received by the transceiver 4901 and may generate feedback information based on the feedback configuration information. The controller 4902 may control the transceiver 4901 to transmit the generated feedback information to the base station at the feedback timing defined in the feedback configuration information.

[0918] Controller 4902 may receive CSI-RS periodically or aperiodically transmitted from a base station, generate feedback information based on the received CSI-RS, and transmit the generated feedback information to the base station. At this time, controller 4902 may select a precoding matrix based on the relationship between antenna port groups of the base station.

[0919] Controller 4902 may receive a CSI-RS periodically or aperiodically transmitted from a base station, generate feedback information based on the received CSI-RS, and transmit the generated feedback information to the base station. In this case, controller 4902 may select a precoding matrix with reference to all antenna port groups of the base station. Furthermore, controller 4902 may receive feedback configuration information from the base station, receive a CSI-RS periodically or aperiodically transmitted from the base station, generate feedback information based on the received feedback configuration information and the received CSI-RS, and transmit the generated feedback information to the base station.

[0920] Figure 50 is a block diagram illustrating an internal structure of a base station according to an embodiment of the present disclosure.

[0921] refer to Figure 50 , the base station includes a controller 5002 and a transceiver 5001.

[0922] Controller 5002 controls the status and operation of all elements in the base station. Specifically, controller 5002 can allocate CSI-RS resources to the UE for estimating the UE's channel, and allocate feedback resources and feedback timing to the UE. To this end, controller 5002 can further include resource allocator 5003. In addition, controller 2210 can allocate feedback configuration and feedback timing to prevent conflicts between feedback from multiple UEs, and receive and analyze the configured feedback information at corresponding timings.

[0923] The transceiver 5001 may transmit and receive reference signals and feedback information to and from the UE. Here, under the control of the controller 5002, the transceiver 5001 may transmit CSI-RSE to the UE via allocated resources and may receive feedback of channel information from the UE.

[0924] Although it is shown that the resource allocator 5003 is included in the controller 5001, it is not limited thereto.

[0925] The controller 5002 may control the transceiver 5001 to transmit configuration information associated with each of the at least one reference signal to the UE, or may generate at least one reference signal. In addition, the controller 5002 may control the transceiver 5001 to transmit feedback configuration information for generating feedback information based on the measurement result to the UE.

[0926] The controller 5002 may control the transceiver 5001 to send at least one reference signal to the UE, and receive feedback information sent from the UE at the feedback timing defined in the feedback configuration information.

[0927] The controller 5002 may send feedback configuration information to the UE, periodically or aperiodically send CSI-RS to the UE, and receive feedback information generated based on the feedback configuration information and the CSI-RS from the UE. In this case, the controller 5002 may send feedback configuration information corresponding to each antenna port group of the base station, as well as additional feedback configuration information based on the relationship between antenna port groups. The controller 5002 may periodically or aperiodically send CSI-RS beamformed based on the feedback information to the UE, and receive feedback information generated based on the CSI-RS from the UE.

Claims

1. A method performed by a user equipment (UE) in a communication system, the method comprising: receiving one or more configurations from a base station via higher layer signaling, wherein the configurations are associated with aperiodic channel state information (CSI) reporting and include information of CSI-reference signal (RS) resources; receiving, from a base station, downlink control information (DCI) including an information field for triggering an aperiodic CSI report, wherein the information field is defined as one of a first interpretation and a second interpretation based on the number of the one or more configurations and a size of the information field, wherein the first interpretation is that the information field directly indicates a configuration among the one or more configurations received via higher layer signaling, and wherein the second interpretation is that the information field indicates a configuration among at least one configuration selected via a medium access control (MAC) control element (CE) among the one or more configurations received via higher layer signaling; receiving an aperiodic CSI-RS from a base station based on an offset of the aperiodic CSI-RS; Sending an aperiodic CSI report including CSI generated based on the aperiodic CSI-RS to the base station, The information of the CSI-RS resource includes information of the bandwidth of the CSI-RS resource, and the bandwidth of the CSI-RS resource is defined in a bandwidth part, and The information of the CSI-RS resource includes information of a frequency offset of the CSI-RS resource, and the frequency offset of the CSI-RS resource is defined in units of N resource blocks (RBs), where N is greater than 1.

2. The method according to claim 1, wherein The offset of the aperiodic CSI-RS corresponds to a CSI-RS resource associated with the aperiodic CSI report indicated based on the information field in the DCI.

3. The method according to claim 1, wherein The configuration includes information about a CSI-RS resource set and a CSI interference measurement CSI-IM resource set.

4. The method according to claim 1, wherein In case all bits of the information field are equal to 0, the information field indicates that aperiodic CSI reporting is not triggered.

5. A method performed by a base station in a communication system, the method comprising: Sending one or more configurations to a user equipment (UE) via higher layer signaling, wherein the configuration is associated with an aperiodic channel state information (CSI) report and includes information of a CSI-reference signal (RS) resource; transmitting downlink control information (DCI) including an information field for triggering an aperiodic CSI report to a UE, wherein the information field is defined as one of a first interpretation and a second interpretation based on the number of the one or more configurations and a size of the information field, wherein the first interpretation is that the information field directly indicates a configuration among the one or more configurations transmitted via higher layer signaling, and wherein the second interpretation is that the information field indicates at least one configuration selected via a medium access control (MAC) control element (CE) among the one or more configurations transmitted via higher layer signaling; Sending an aperiodic CSI-RS to the UE based on the offset of the aperiodic CSI-RS; receiving an aperiodic CSI report from the UE including CSI generated based on the aperiodic CSI-RS, The information of the CSI-RS resource includes information of the bandwidth of the CSI-RS resource, and the bandwidth of the CSI-RS resource is defined in a bandwidth part, and The information of the CSI-RS resource includes information of a frequency offset of the CSI-RS resource, and the frequency offset of the CSI-RS resource is defined in units of N resource blocks (RBs), where N is greater than 1.

6. The method according to claim 5, wherein: The offset of the aperiodic CSI-RS corresponds to a CSI-RS resource associated with the aperiodic CSI report indicated based on the information field in the DCI.

7. The method according to claim 5, wherein: The configuration includes information about a CSI-RS resource set and a CSI interference measurement CSI-IM resource set.

8. The method according to claim 5, wherein In case all bits of the information field are equal to 0, the information field indicates that aperiodic CSI reporting is not triggered.

9. A user equipment (UE) in a communication system, the UE comprising: transceivers, and; The controller is configured as: receiving one or more configurations from a base station via higher layer signaling, wherein the configurations are associated with aperiodic channel state information (CSI) reporting and include information of CSI-reference signal (RS) resources; receiving, from a base station, downlink control information (DCI) including an information field for triggering an aperiodic CSI report, wherein the information field is defined as one of a first interpretation and a second interpretation based on the number of the one or more configurations and a size of the information field, wherein the first interpretation is that the information field directly indicates a configuration among the one or more configurations received via higher layer signaling, and wherein the second interpretation is that the information field indicates a configuration among at least one configuration selected via a medium access control (MAC) control element (CE) among the one or more configurations received via higher layer signaling; receiving an aperiodic CSI-RS from a base station based on an offset of the aperiodic CSI-RS; and Sending an aperiodic CSI report including CSI generated based on the aperiodic CSI-RS to the base station, The information of the CSI-RS resource includes information of the bandwidth of the CSI-RS resource, and the bandwidth of the CSI-RS resource is defined in a bandwidth part, and The information of the CSI-RS resource includes information of a frequency offset of the CSI-RS resource, and the frequency offset of the CSI-RS resource is defined in units of N resource blocks (RBs), where N is greater than 1.

10. The UE according to claim 9, wherein: The offset of the aperiodic CSI-RS corresponds to a CSI-RS resource associated with the aperiodic CSI report indicated based on the information field in the DCI.

11. The UE according to claim 9, wherein: The configuration includes information about a CSI-RS resource set and a CSI interference measurement CSI-IM resource set.

12. The UE according to claim 9, wherein: In case all bits of the information field are equal to 0, the information field indicates that aperiodic CSI reporting is not triggered.

13. A base station in a communication system, the base station comprising: transceiver; as well as The controller is configured as: Sending one or more configurations to a user equipment (UE) via higher layer signaling, wherein the configuration is associated with an aperiodic channel state information (CSI) report and includes information of a CSI-reference signal (RS) resource; transmitting downlink control information (DCI) including an information field for triggering an aperiodic CSI report to a UE, wherein the information field is defined as one of a first interpretation and a second interpretation based on the number of the one or more configurations and a size of the information field, wherein the first interpretation is that the information field directly indicates a configuration among the one or more configurations transmitted via higher layer signaling, and wherein the second interpretation is that the information field indicates at least one configuration selected via a medium access control (MAC) control element (CE) among the one or more configurations transmitted via higher layer signaling; Sending an aperiodic CSI-RS to the UE based on the offset of the aperiodic CSI-RS; and receiving an aperiodic CSI report from the UE including CSI generated based on the aperiodic CSI-RS, The information of the CSI-RS resource includes information of the bandwidth of the CSI-RS resource, and the bandwidth of the CSI-RS resource is defined in a bandwidth part, and The information of the CSI-RS resource includes information of a frequency offset of the CSI-RS resource, and the frequency offset of the CSI-RS resource is defined in units of N resource blocks (RBs), where N is greater than 1.

14. The base station according to claim 13, wherein: The offset of the aperiodic CSI-RS corresponds to a CSI-RS resource associated with the aperiodic CSI report indicated based on the information field in the DCI.

15. The base station according to claim 13, wherein: The configuration includes information about a CSI-RS resource set and a CSI interference measurement CSI-IM resource set.

16. The base station according to claim 13, wherein: In case all bits of the information field are equal to 0, the information field indicates that aperiodic CSI reporting is not triggered.

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