Method and device for transmitting and receiving downlink reference signal in wireless communication system

Abstract

The present disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate than a 4G communication system, such as LTE. A method performed by a terminal (user equipment) in a wireless communication system, according to one embodiment, may comprise the steps of: receiving, from a base station, at least one of downlink control information (DCI) or a medium access control (MAC) control element (CE) including demodulation reference signal (DMRS) allocation information and scheduling information; identifying a DMRS port to which a data signal for a physical downlink shared channel (PDSCH) and a DMRS are allocated on the basis of the DMRS allocation information; receiving the data signal and the DMRS on the basis of the identified DMRS port; and demodulating the PDSCH on the basis of the DMRS and the data signal. Various other embodiments identified through the specification are possible.

Description

Method and device for transmitting and receiving a downlink reference signal in a wireless communication system

[0001] The present disclosure relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting and receiving a downlink reference signal in a wireless communication system.

[0002] Looking back at the evolution of wireless communication over successive generations, technologies have primarily been developed for human-facing services such as voice, multimedia, and data. With the commercialization of the 5G (5th Generation) communication system, an explosive increase in connected devices is expected to be connected to communication networks. Examples of networked objects include vehicles, robots, drones, home appliances, displays, smart sensors installed in various infrastructures, construction equipment, and factory equipment. Mobile devices are also expected to evolve into diverse form factors, such as augmented reality glasses, virtual reality headsets, and holographic devices. In the 6G (6th Generation) era, efforts are being made to develop improved 6G communication systems to connect hundreds of billions of devices and objects and provide diverse services. For this reason, 6G communication systems are often referred to as "beyond 5G."

[0003] The 6G communication system, expected to be realized around 2030, will have a maximum transmission speed of terabytes (i.e., 1,000 gigabits) per second (bps) and a wireless latency of 100 microseconds (μsec). In other words, compared to 5G, the transmission speed in a 6G communication system will be 50 times faster and the wireless latency will be reduced to one-tenth.

[0004] To achieve these high data rates and ultra-low latency, 6G communication systems are being considered for implementation in the terahertz (THz) band (e.g., from 95 gigahertz (GHz) to 3 terahertz (THz)). Compared to the millimeter wave (mmWave) band introduced in 5G, the terahertz band is expected to have more severe path loss and atmospheric absorption, making it more important to develop technologies that can guarantee signal reach, or coverage. Key technologies to ensure coverage include Radio Frequency (RF) components, antennas, new waveforms that offer better coverage than Orthogonal Frequency Division Multiplexing (OFDM), beamforming, and multiple antenna transmission technologies such as massive Multiple-Input and Multiple-Output (MIMO), Full Dimensional MIMO (FD-MIMO), array antennas, and large-scale antennas. In addition, new technologies such as metamaterial-based lenses and antennas, high-dimensional spatial multiplexing using Orbital Angular Momentum (OAM), and Reconfigurable Intelligent Surface (RIS) are being discussed to improve the coverage of terahertz band signals.

[0005] In addition, in order to improve frequency efficiency and system network, 6G communication systems are developing full duplex technology that utilizes the same frequency resources at the same time for uplink and downlink; network technology that integrates satellites and HAPS (High-Altitude Platform Stations); network structure innovation technology that supports mobile base stations and enables optimization and automation of network operation; dynamic spectrum sharing technology through collision avoidance based on spectrum usage prediction; AI-based communication technology that utilizes AI (Artificial Intelligence) from the design stage and internalizes end-to-end AI support functions to realize system optimization; and next-generation distributed computing technology that realizes services with complexity that exceeds the limits of terminal computing capabilities by utilizing ultra-high-performance communication and computing resources (Mobile Edge Computing (MEC), cloud, etc.). In addition, efforts are being made to further strengthen connectivity between devices, further optimize networks, promote softwareization of network entities, and increase the openness of wireless communications through the design of new protocols to be used in 6G communication systems, the implementation of hardware-based security environments, the development of mechanisms for the safe use of data, and the development of technologies for maintaining privacy.

[0006] Research and development of these 6G communication systems are expected to enable a new level of hyper-connected experience through the hyper-connectivity of 6G communication systems, which encompass not only connections between things but also connections between people and things. Specifically, 6G communication systems are expected to enable services such as truly immersive eXtended Reality (XR), high-fidelity mobile holograms, and digital replicas. Furthermore, services such as remote surgery, industrial automation, and emergency response, which are provided through 6G communication systems through enhanced security and reliability, will be applied in various fields such as industry, medicine, automobiles, and home appliances.

[0007] Based on the discussion described above, the present disclosure seeks to provide a method and device for transmitting and receiving an effective downlink reference signal in a wireless communication system.

[0008] More specifically, the present disclosure provides a method and apparatus for reducing overhead for downlink reference signal transmission.

[0009] According to one embodiment disclosed in the present document, a method performed by a user equipment in a wireless communication system may include the steps of receiving, from a base station, at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE), identifying a DMRS port to which a data signal and a DMRS for a physical downlink shared channel (PDSCH) are allocated based on the DMRS allocation information, receiving the data signal and the DMRS based on the identified DMRS port, and demodulating the PDSCH based on the DMRS and the data signal.

[0010] According to one embodiment disclosed in the present document, in a wireless communication system, a user equipment includes a transceiver and a controller coupled to the transceiver, and the controller is configured to receive, from a base station, at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE), identify a DMRS port to which a data signal and a DMRS for a physical downlink shared channel (PDSCH) are allocated based on the DMRS allocation information, receive the data signal and the DMRS based on the identified DMRS port, and demodulate the PDSCH based on the DMRS and the data signal.

[0011] According to one embodiment disclosed in the present document, a method performed by a base station in a wireless communication system includes the steps of identifying a DMRS port through which a data signal is transmitted and a demodulation reference signal (DMRS) is not transmitted, and transmitting, to a user equipment (UE), at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE), wherein the DMRS allocation information can be used by the user equipment to identify a DMRS port to which a data signal and DMRS for a physical downlink shared channel (PDSCH) are allocated.

[0012] According to one embodiment disclosed in the present document, in a wireless communication system, a base station includes a transceiver and a controller coupled to the transceiver, and the controller is configured to identify a DMRS port through which a data signal is transmitted but a demodulation reference signal (DMRS) is not transmitted, and to transmit, to a user equipment (UE), at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE), wherein the DMRS allocation information can be used by the user equipment to identify a DMRS port to which a data signal and a DMRS for a physical downlink shared channel (PDSCH) are allocated.

[0013] FIG. 1 illustrates an example of a region of wireless resources in a wireless communication system according to one embodiment of the present disclosure.

[0014] FIG. 2 illustrates a resource structure when switching a demodulation reference signal (DMRS) port according to one embodiment of the present disclosure.

[0015] FIG. 3 illustrates an example of switching a DMRS port according to one embodiment of the present disclosure.

[0016] FIG. 4 illustrates an example in which a base station transmits a signal including a DMRS-empty indicator to a terminal when switching a DMRS port according to one embodiment of the present disclosure.

[0017] FIG. 5 illustrates a resource structure when switching DMRS ports according to one embodiment of the present disclosure.

[0018] FIG. 6 illustrates an example of a base station transmitting a signal including an inactive DMRS field value / active DMRS field value to a terminal when switching a DMRS port in a slot according to one embodiment of the present disclosure.

[0019] FIG. 7 illustrates an example of a base station transmitting a signal including an interference reuse field to a terminal when switching a DMRS port in a slot according to one embodiment of the present disclosure.

[0020] FIG. 8 illustrates an example of a base station transmitting a DMRS port switching pattern to a terminal when switching a DMRS port in a super slot according to one embodiment of the present disclosure.

[0021] FIG. 9 illustrates an example of a base station transmitting a DMRS port switching pattern to a terminal when switching a DMRS port in a super-slot according to one embodiment of the present disclosure.

[0022] FIG. 10 illustrates an example of a base station transmitting a signal including a DMRS port switching pattern and an inactive DMRS field to a terminal when switching a DMRS port in a super-slot according to one embodiment of the present disclosure.

[0023] FIG. 11 illustrates the operation of a base station and a terminal when switching a DMRS port according to one embodiment of the present disclosure.

[0024] FIG. 12 illustrates the operation of a terminal according to one embodiment of the present disclosure.

[0025] FIG. 13 illustrates the operation of a base station according to one embodiment of the present disclosure.

[0026] FIG. 14 illustrates the structure of a terminal according to one embodiment of the present disclosure.

[0027] FIG. 15 illustrates the structure of a base station according to one embodiment of the present disclosure.

[0028] In connection with the description of the drawings, the same or similar reference numerals may be used for identical or similar components.

[0029] Various aspects of the claimed subject matter are described with reference to the drawings, wherein like reference numerals are used to designate similar elements. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of one or more embodiments. However, it may be apparent that the embodiments may be practiced without these specific details.

[0030] The terms used in this disclosure are used only to describe specific embodiments and may not be intended to limit the scope of other embodiments. The singular expression may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as commonly understood by those of ordinary skill in the art described in this disclosure. Terms defined in general dictionaries among the terms used in this disclosure may be interpreted as having the same or similar meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined in this disclosure. In some cases, even if a term is defined in this disclosure, it cannot be interpreted to exclude embodiments of the present disclosure.

[0031] In the following description, terms referring to signals (e.g., message, signal, signaling, sequence, stream), terms referring to resources (e.g., symbol, slot, subframe, radio frame, subcarrier, resource element (RE), resource block (RB), bandwidth part (BWP), occasion), terms for operations (e.g., step, method, process, procedure), terms referring to data (e.g., information, parameter, variable, value, bit, symbol, codeword), terms referring to channels, terms referring to control information (e.g., downlink control information (DCI), medium access control code word element (MAC CE), radio resource control (RRC) signaling), terms referring to network entities, terms referring to components of devices, etc. are used in the description. These terms are provided for convenience. Therefore, the present disclosure is not limited to the terms described below, and other terms with equivalent technical meanings may be used.

[0032] Various embodiments of the present disclosure are described herein with respect to a wireless terminal and / or a base station. A wireless terminal may refer to a device that provides voice and / or data connectivity to a user. A wireless terminal may be connected to a computing device, such as a laptop or desktop computer, or may be a self-contained device, such as a personal digital assistant (PDA). A wireless terminal may also be referred to as a system, a subscriber unit, a subscriber station, a mobile station, a mobile, a mobile device, a remote station, a remote terminal, an access terminal, a user terminal, a terminal, a wireless communication device, a user agent, a user device, or user equipment. A wireless terminal may be a subscriber station, a wireless device, a cellular telephone, a PCS telephone, a cordless telephone, a Session Initiation Protocol (SIP) telephone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless access capabilities, or another processing device connected to a wireless modem. A base station (e.g., an access point) may refer to a device within an access network that communicates with wireless terminals over a wireless interface through one or more sectors. The base station can incorporate an Internet Protocol (IP) network by converting received air interface frames into IP packets and can act as a router between the wireless terminals and the rest of the access network. The base station can also coordinate the management of attributes for the air interface.

[0033] The embodiment disclosed in this document considers a MIMO-OFDM system in which a code division multiplexing (CDM) scheme is applied as a signal multiplexing scheme. In addition, the present disclosure estimates the channel of each CDM group by estimating the resource elements within the resource block. It is assumed that demodulation reference signals (DM-RSs) that are already known to the receiver are transmitted through the resource elements.

[0034] The embodiments disclosed in this document relate to a wireless communication system, and more specifically, assume a multi-user multiple-input multiple-output (MU-MIMO) system. MIMO communication systems are a technology that can dramatically increase the transmission speed and stability of wireless communications, and are utilized as a core element technology in various wireless communication systems.

[0035] The existing DMRS transmitting and receiving operation can transmit information for scheduling slots N to N+1 from the base station to the terminal along with DCI. At this time, antenna port field information is included in the DCI field, and the terminal can recognize information about the number of CDM groups transmitted in the resource scheduled by the DCI, the DMRS port index allocated to the terminal, the number of layers, and the number of front-load symbols to which the DMRS is mapped through the received antenna port field. For example, when terminal 1 receives information about antenna port 45 from the base station, the terminal can recognize information according to antenna port 45.

[0036] The embodiment proposed in this document proposes a method for reducing the overhead of demodulation reference signal (DMRS) associated with multi-layer transmission in an MU-MIMO system.

[0037] When transmitting DMRS of multiple layers in an MU-MIMO system, a large number of DMRS ports may be required. At this time, since DMRS is transmitted in each slot, overhead due to DMRS transmission may occur when transmitting a large number of layers. At this time, as the number of DMRS ports increases, the resource elements (REs) occupied by DMRS increase, which may cause a problem in that the number of REs for transmitting data signals decreases, resulting in a rapid decrease in transmission performance of the terminal. For example, in the case of Type 2 DMRS, an overhead due to DMRS transmission of approximately 14.3% occurs for 12 multi-layer transmissions, and an overhead of 57.1% may occur for 48 multi-layer transmissions.

[0038] Accordingly, the present disclosure proposes a DMRS operation method capable of reducing overhead associated with DMRS transmission when transmitting DMRS through a large number of layers in a 6G communication system.

[0039] The embodiment of the present disclosure assumes that, in a MU-MIMO system, when transmitting DMRS through multiple layers, the DMRS is not transmitted at every slot, but rather intermittently (or in segments) depending on the transmission environment of the terminal (e.g., modulation and coding scheme (MCS), signal-to-noise ratio (SNR), mobility, etc.). For example, the embodiment of the present disclosure assumes that, as illustrated in FIGS. 2, 4, and 10, not all DMRSs are transmitted in a specific slot, or some DMRS ports of a specific slot are not transmitted.

[0040] FIG. 1 illustrates an example of a region of wireless resources in a wireless communication system according to one embodiment of the present disclosure.

[0041] In various embodiments of the present disclosure, the wireless resource domain may include a structure in the time-frequency domain. In one embodiment, the wireless communication system may include an NR communication system.

[0042] Referring to Fig. 1, in the wireless resource domain, the horizontal axis represents the time domain, and the vertical axis represents the frequency domain. The length of a radio frame (104) is 10 ms. The radio frame (104) may be a time domain section composed of 10 subframes. The length of a subframe (203) is 1 ms. The unit of configuration in the time domain may be an OFDM (orthogonal frequency division multiplexing) and / or a DFT-s-OFDM (DFT (discrete Fourier transform)-spread-OFDM) symbol, and N symb OFDM and / or DFT-s-OFDM symbols (101) may be grouped to form one slot (102). In various embodiments, an OFDM symbol may include a symbol for transmitting and receiving a signal using an OFDM multiplexing scheme, and a DFT-s-OFDM symbol may include a symbol for transmitting and receiving a signal using a DFT-s-OFDM or SC-FDMA (single carrier frequency division multiple access) multiplexing scheme. The minimum transmission unit in the frequency domain is a subcarrier, and the carrier bandwidth constituting the resource grid is a total of N SC It can be composed of BW sub-carriers (105). In addition, in the present disclosure, an embodiment regarding downlink signal transmission and reception is described for convenience of explanation, but this can also be applied to an embodiment regarding uplink signal transmission and reception.

[0043] In some embodiments, the number of slots (102) constituting one subframe (103) and the length of the slots (102) may vary depending on the subcarrier spacing. This subcarrier spacing is defined by numerology ( ) can be referred to as. That is, the subcarrier spacing, the number of slots included in a subframe, the length of the slot, and the length of the subframe can be configured variably. For example, in an NR communication system, when the subcarrier spacing (SCS) is 15 kHz, one slot (102) constitutes one subframe (103), and the lengths of the slot (102) and the subframe (103) can each be 1 ms. In addition, for example, when the subcarrier spacing is 30 kHz, two slots can constitute one subframe (103). In this case, the length of the slot is 0.5 ms and the length of the subframe is 1 ms.

[0044] In some embodiments, the subcarrier spacing, the number of slots included in a subframe, the length of the slot, and the length of the subframe may be applied variably depending on the communication system. For example, in the case of an LTE system, the subcarrier spacing is 15 kHz, two slots constitute one subframe, and in this case, the length of the slot may be 0.5 ms and the length of the subframe may be 1 ms. For another example, in the case of an NR system, the subcarrier spacing ( ) can be one of 15kHz, 30kHz, 60kHz, 120kHz, 240kHz, and the subcarrier spacing ( ) the number of slots included in one subframe can be 1, 2, 4, 8, or 16.

[0045] The basic unit of resources in the time-frequency domain may be a resource element (RE) (106), and the resource element (106) may be expressed by an OFDM symbol index and a subcarrier index. A resource block may include a plurality of resource elements. In an NR system, a resource block (RB) (or physical resource block (PRB)) (107) may be N in the frequency domain. SC RB can be defined as a series of consecutive subcarriers. The number of subcarriers is N. SC RB=12. The frequency domain may include common resource blocks (CRBs). Physical resource blocks (PRBs) may be defined in the bandwidth part (BWP) of the frequency domain. The CRB and PRB numbers may be determined differently depending on the subcarrier spacing. In the LTE system, RBs are N in the time domain. symb N consecutive OFDM symbols in the frequency domain SC RB can be defined as a series of consecutive sub-carriers.

[0046] In NR and / or LTE systems, scheduling information for downlink data or uplink data may be transmitted from a base station to a terminal via downlink control information (DCI). In various embodiments, DCI may be defined according to various formats, and each format may indicate whether the DCI includes scheduling information for uplink data (e.g., UL grant), scheduling information for downlink data (DL resource allocation), whether it is compact DCI with small control information size, whether it is fall-back DCI, whether spatial multiplexing using multiple antennas is applied, and / or whether it is DCI for power control. For example, NR DCI format 1_0 or NR DCI format 1_1 may include scheduling for downlink data. Additionally, for example, NR DCI format 0_0 or NR DCI format 0_1 ​​may include scheduling for uplink data.

[0047] As described above, FIG. 1 illustrates an example of a downlink and uplink slot structure in a wireless communication system. In particular, FIG. 1 illustrates the structure of a resource grid of a 3GPP NR system. Referring to FIG. 1, a slot may include a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and a plurality of resource blocks (RBs) in the frequency domain. A signal may be composed of part or all of the resource grid. In addition, the number of OFDM symbols included in a single slot may generally vary depending on the length of a cyclic prefix (CP). In FIG. 1, for convenience of explanation, a case in which a single slot consists of 14 OFDM symbols is illustrated, but the signal referred to in the present disclosure does not specify the configuration of symbols. In addition, the modulation method of the generated signal is not limited to a specific value of QAM (Quadrature Amplitude Modulation), and can follow the modulation methods of various communication standards, such as BPSK (Binary phase-shift keying) and QPSK (Quadrature Phase Shift Keying).

[0048] While various embodiments of the present disclosure are described based on an LTE communication system or an NR communication system, the contents of the present disclosure are not limited thereto and can be applied to various wireless communication systems for transmitting downlink or uplink control information. Furthermore, the contents of the present disclosure can be applied to unlicensed bands as needed in addition to licensed bands.

[0049] Hereinafter, in the present disclosure, higher layer signaling or higher signal may be a signal transmission method in which a base station transmits a signal to a user terminal using a downlink data channel of a physical layer, or from a user terminal to a base station using an uplink data channel of a physical layer. According to an embodiment, the higher layer signaling may include at least one of radio resource control (RRC) signaling, signaling according to an F1 interface between a centralized unit (CU) and a distributed unit (DU), or a signal transmission method transmitted through a media access control (MAC) control element (MAC CE). In addition, according to an embodiment, the higher layer signaling or higher signal may include system information commonly transmitted to a plurality of user terminals, for example, a system information block (SIB).

[0050] In a 5G wireless communication system, a synchronization signal block (SSB) (also referred to as an SS block, SS / PBCH block, etc.) may be transmitted for initial access, and the synchronization signal block may be composed of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a physical broadcast channel (PBCH). In the initial access phase when a user equipment (UE) first accesses the system, the user equipment may acquire downlink time and frequency domain synchronization and a cell ID (cell ID) from a synchronization signal through a cell search procedure. The synchronization signal may include a PSS and an SSS. The user equipment may receive a PBCH including a master information block (MIB) from a base station to acquire system information and basic parameter values ​​related to transmission and reception, such as system bandwidth or related control information. Based on the received PBCH, the user terminal can decode the physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH) to obtain a system information block (SIB). The user terminal then exchanges its identity with the base station through a random access phase and undergoes registration, authentication, and other steps to gain initial access to the network.

[0051] FIG. 2 illustrates a resource structure when switching a demodulation reference signal (DMRS) port according to one embodiment of the present disclosure.

[0052] Fig. 2 assumes an embodiment in which 24 layers (L = 24) and 24 DMRS ports are divided into two subsets (G = 2), and DMRS ports are switched when the number of simultaneously scheduled terminals is 6. The resource structure of Fig. 2 may include CDM groups 1 to 6 for DMRS. In this case, CDM groups 1 to 6 may refer to signals transmitted and received by terminals 1 to 6, respectively.

[0053] Referring to FIG. 2, for pattern ID 1 of DMRS port switching, all DMRS ports may be transmitted in slot 0, and not all DMRS ports may be transmitted in slot 1. Additionally, all DMRS ports may be transmitted in slot 2, and not all DMRS ports may be transmitted in slot 3.

[0054] For pattern ID 2 of DMRS port switching, all DMRS ports may transmit in slot 0, and not all DMRS ports may transmit in slot 1. In slot 2, only DMRS ports corresponding to CDM group 0, CDM group 1, and CDM group 2 may transmit, and in slot 3, only DMRS ports corresponding to CDM group 3, CDM group 4, and CDM group 5 may transmit.

[0055] In this way, there may be slots where not all DMRS ports transmit.

[0056] FIG. 3 illustrates an example of switching a DMRS port according to one embodiment of the present disclosure. FIG. 3 illustrates an operation of switching a DMRS port corresponding to the resource structure illustrated in FIG. 2.

[0057] Referring to FIG. 3, in the case of DMRS port switching pattern ID 2 of FIG. 2, only DMRS ports corresponding to CDM group 0, CDM group 1, and CDM group 2 may be transmitted in slot 2, and DMRS ports corresponding to CDM group 3, CDM group 4, and CDM group 5 may not be transmitted.

[0058] Accordingly, in slot 2, terminals 1 to 3 corresponding to CDM group 0, CDM group 1, and CDM group 2 can receive DMRS, respectively. Terminals 4 to 6 corresponding to CDM group 3, CDM group 4, and CDM group 5 can receive data signals, since DMRS is not transmitted.

[0059] FIG. 4 illustrates an example in which a base station transmits a signal including a DMRS-empty indicator to a terminal when switching a DMRS port according to one embodiment of the present disclosure.

[0060] Figure 4 assumes an embodiment of 12-layer (L = 12) DMRS ports transmitting and receiving, and switching DMRS ports when the number of simultaneously scheduled terminals is three. Furthermore, it is assumed that four layers are allocated to each terminal.

[0061] According to one embodiment of the present disclosure, a data signal may be transmitted in a resource where a base station does not send a DMRS to a terminal, but a DMRS for the data signal may not be transmitted. Accordingly, the base station may inform the terminal, through a DMRS-empty indicator, that no DMRS is transmitted on the DMRS port associated with the terminal and thus an instruction to reuse the last acquired DMRS. That is, the DMRS allocation information that the terminal receives from the base station may include the DMRS-empty indicator. The DMRS-empty indicator may mean an indicator indicating that no DMRS is transmitted on the DMRS port associated with the terminal and thus the terminal should reuse the last received DMRS port. Meanwhile, the DMRS-empty indicator may be transmitted from the base station to the terminal via DCI or MAC CE.

[0062] According to one embodiment of the present disclosure, when the DMRS-empty indicator is 1, a DMRS is not transmitted on the resource allocated to the terminal, but a data signal is transmitted, so it may be indicated to reuse the last acquired DMRS port. When the DMRS-empty indicator received from the base station is 1, the terminal may demodulate a data signal for a physical downlink shared channel (PDSCH) scheduled by DCI or a data signal for a PDSCH indicated by MAC CE using the last acquired DMRS port. For example, referring to FIG. 4, in slot 5, terminals 1 to 3 may be allocated to CDM group 0, CDM group 1, and CDM group 2, respectively, and DMRS ports corresponding to CDM group 0, CDM group 1, and CDM group 2 may be transmitted. When a base station transmits DCI for scheduling slots 5 through 6 to terminal 1, the DCI may include information about antenna ports (e.g., information that the antenna port is 45) as well as information that a DMRS-empty indicator is 1 to indicate that there are no DMRS-allocated resources in slot 6. Based on the information that the DMRS-empty indicator is 1 for slot 6 from the base station, terminal 1 can decode a data signal for a PDSCH using the DMRS port that terminal 1 acquired last.

[0063] According to one embodiment of the present disclosure, when the DMRS-empty indicator is 0, it can indicate that the DMRS is transmitted on the resource allocated to the terminal, and thus, the last acquired DMRS port does not need to be reused. For example, in FIG. 4, when the base station transmits DCI to schedule slot 7 to terminal 1 in slot 6, the DCI can be transmitted including information about the antenna port as well as information that the DMRS-empty indicator is 0 to indicate that the DMRS is transmitted on the DMRS port corresponding to CDM group 0 associated with terminal 1 in slot 7. Terminal 1 can receive the DMRS based on the information that the DMRS-empty indicator for slot 7 is 0 from the base station.

[0064] FIG. 5 illustrates a resource structure when switching DMRS ports according to one embodiment of the present disclosure.

[0065] A situation may arise where a UE incorrectly perceives that DMRS is being transmitted on a resource associated with a CDM group based on the antenna port value, when in fact its own data signal is being transmitted on the resource associated with the CDM group where DMRS is not being transmitted. In this case, a problem may arise where the UE cannot receive the data signal. [Table 1] shows information about antenna port values ​​according to 3GPP TS 38.212. Specifically, [Table 1] shows the number of CDM groups, DMRS ports, and front-load symbols according to the antenna port value. In one example, a UE can recognize the number of CDM groups, DMRS ports, and front-load symbols according to the antenna port value based on [Table 1].

[0066]

[0067] For example, in FIG. 5, terminal 1 associated with CDM group 0 resources may recognize that DMRS is being transmitted from CDM group 1 and CDM group 2 via antenna port 45 in slot 6 according to [Table 1], but in reality, data signals may be transmitted from resources associated with CDM group 2. For another example, in FIG. 5, terminal 1 associated with CDM group 0 resources may recognize that DMRS is being transmitted from CDM group 1 and CDM group 2 via antenna port 45 in slot 7, but in reality, data signals may be transmitted from resources associated with CDM group 1.

[0068] In resources where data signals for other terminals are transmitted but DMRS is not, interference signals for terminals not transmitting DMRS may not be correctly recognized, and it may be difficult to mitigate interference between terminals using a MIMO receiver. For example, a terminal may perceive that DMRS is being transmitted through the value of its antenna port, but may not recognize the interference signal due to another terminal (e.g., a hidden UE) actually transmitting a data signal.

[0069] For example, in FIG. 5, terminal 1 associated with CDM group 0 can receive an interference signal for terminal 2 through DMRS transmitted in CDM group 1 in slot 6, but cannot correctly receive an interference signal for terminal 3 in CDM group 2 where no DMRS is transmitted. For another example, in FIG. 5, terminal 1 associated with CDM group 0 can receive an interference signal for terminal 3 through DMRS transmitted in CDM group 2 in slot 7, but cannot correctly receive an interference signal for terminal 2 in CDM group 1 where no DMRS is transmitted.

[0070] FIG. 6 illustrates an example in which a base station transmits a signal including an inactive DMRS field value or an active DMRS field value to a terminal when switching a DMRS port in a slot according to one embodiment of the present disclosure. Specifically, FIG. 6 illustrates an example in which a base station transmits a signal to a terminal when DMRS ports corresponding to some CDM groups among CDM groups to which DMRSs known to the terminal are assigned through existing DMRS port fields are not transmitted due to DMRS port switching.

[0071] According to one embodiment of the present disclosure, a base station may signal information to a terminal about resources where data signals are transmitted instead of DMRSs among CDM groups to which DMRSs are allocated, which the terminal is aware of, through an existing DMRS port field due to DMRS port switching. At this time, signaling of information about resources where data signals are transmitted instead of DMRSs may be performed in the form of DCI or MAC CE. In one example, the base station may signal information about CDM groups where DMRSs are not transmitted among CDM groups to which no terminals are assigned. At this time, information about CDM groups where DMRSs are not transmitted may be signaled as an inactive DMRS field. In one example, the base station may signal information about CDM groups where DMRSs are transmitted, among CDM groups to which no terminals are assigned. At this time, information about CDM groups where DMRSs are transmitted may be signaled as an active DMRS field.

[0072] Referring to FIG. 6, slot 5 is allocated to CDM group 1, CDM group 2, and CDM group 3 for terminals 1 to 3, respectively, and DMRS ports corresponding to CDM group 1, CDM group 2, and CDM group 3 can be transmitted. For example, when a base station transmits DCI to schedule terminal 1 for slot 6 from slot 5, the DCI may include information about the antenna port (e.g., information that the antenna port is 45) as well as an inactive DMRS field indicating that DMRS is not transmitted on resources corresponding to CDM group 2 (e.g., inactive DMRS = {CDM group 2}). In addition, the base station may transmit the DCI by including an active DMRS field indicating that DMRS is transmitted on resources corresponding to CDM group 1 due to antenna port switching (e.g., active DMRS = {CDM group 1}). Additionally, for example, DCI may also include information where the DMRS-empty indicator described in FIG. 4 is 0.

[0073] A terminal can identify a resource that transmits a data signal without transmitting a DMRS, based on information about an inactive DMRS field or an active DMRS field received from a base station. The terminal can calculate a covariance matrix based on the received data signal. In addition, the terminal can estimate a channel based on the received DMRS signal. Based on the covariance matrix and the estimated channel, the terminal can receive a data signal by calculating an MMSE (minimum mean square error)-IRC (interference rejection combining) receiver. The matrix of the MMSE-IRC receiver can mean a covariance matrix according to the MMSE channel estimation. The matrix of the MMSE-IRC receiver can be calculated according to the formula in [Table 2].

[0074]

[0075] W as described in [Table 2] RX,1 (k,l) represents the weight matrix of the MMSE-IRC receiver, represents the channel estimation matrix, and R -1 represents the covariance matrix.

[0076] In one example, if terminal 1 in FIG. 6 receives information from the base station that the inactive DMRS field is CDM group 2 or the active DMRS field is CDM group 1 in relation to slot 6, terminal 1 can recognize that DMRS is not transmitted in CDM group 2 in slot 6. Accordingly, terminal 1 can receive the data signal by calculating a covariance matrix based on the data signal received in CDM group 2 and calculating an MMSE-IRC receiver according to [Table 2] based on the channel estimated in slot 6.

[0077] In one example, when scheduling from slot 6 to slot 7 in FIG. 6 is performed for terminal 1, DMRS ports corresponding to CDM group 1 in slot 7 may not actually be transmitted due to DMRS port switching when antenna port 45 is allocated. In this case, the base station may inform the terminal of information about the CDM group in which DMRS is not transmitted through an inactive DMRS field (inactive DMRS = {CDM group 1}) or an active DMRS field (active DMRS = {CDM group 2}) in the DCI or MAC CE transmitted. Since terminal 1 can recognize that DMRS is not transmitted in CDM group 1 in slot 7, it can calculate a covariance matrix based on the data signal received in CDM group 1, and calculate an MMSE-IRC receiver based on the channel estimated in slot 7 to receive the data signal.

[0078] FIG. 7 illustrates an example of a base station transmitting a signal including an interference reuse field to a terminal when switching a DMRS port in a slot according to one embodiment of the present disclosure. Specifically, FIG. 7 illustrates an example of a base station signaling to a terminal that the terminal's last measured interference information is also valid on a specific resource, in a resource where DMRS is not transmitted.

[0079] According to one embodiment of the present disclosure, a base station may signal information to a terminal regarding the ID of a CDM group for which the last measured interference information is valid. In this case, the information regarding the ID of the CDM group for which the interference information is valid may be provided as an interference reuse field. Signaling regarding the ID of the CDM group for which the interference information is valid may be performed in the form of DCI or MAC CE.

[0080] In one example, referring to FIG. 7, terminal 1 can receive information from the base station that interference information for CDM group 2 in slot 6 is valid (e.g., interference reuse = {CDM group 2}) through DCI or MAC CE. Terminal 1 can reuse interference information for CDM group 2 measured in slot 5 in slot 6 based on the information received from the base station. Additionally, terminal 1 can measure interference information for CDM group 1 based on DMRS measured in slot 6. Terminal 1 can calculate MMSE-IRC receiver based on the reused interference information for CDM group 2 and the measured interference information for CDM group 1.

[0081] In one example, referring to FIG. 7, terminal 1 can receive information from a base station that interference information of CDM group 1 in slot 7 is valid (e.g., interference reuse = {CDM group 1}) through DCI or MAC CE. Terminal 1 can reuse interference information for CDM group 1 measured in slot 6 in slot 7 based on the information received from the base station. Additionally, terminal 1 can measure interference information for CDM group 2 based on DMRS measured in slot 7. Terminal 1 can calculate MMSE-IRC receiver based on the reused interference information for CDM group 1 and the measured interference information for CDM group 2.

[0082] FIG. 8 illustrates an example of a base station transmitting a DMRS port switching pattern to a terminal when switching DMRS ports in a super slot according to one embodiment of the present disclosure. Specifically, an example of switching DMRS ports based on RRC signaling is illustrated when the base station transmits 12 DMRS ports in a super slot structure.

[0083] FIGS. 2 to 7 illustrate the operations of a base station and a terminal based on a general slot structure, and FIG. 8 illustrates the operations of a base station and a terminal based on a super-slot structure that combines multiple slots. The super-slot structure may represent a structure that combines multiple slots as the slot length becomes shorter in the cmWave band in the general slot structure. In the super-slot structure, a terminal may receive scheduling information for multiple slots, i.e., a super-slot, with a single DCI, rather than receiving scheduling information for one slot from the base station with a single DCI. Meanwhile, a super-slot may represent multiple slots.

[0084] The length of a super-slot can be configured via RRC signaling. The length of a super-slot can refer to the number of slots associated with the super-slot. For example, the length of a super-slot can be configured using PDSCH Configuration.

[0085] According to one embodiment of the present disclosure, a base station can provide information about the switching patterns of DMRS ports transmitted across multiple slots via RRC signaling. Furthermore, the base station can indicate one of the DMRS port switching patterns via DCI or MAC CE. This allows a terminal to know the switching pattern of DMRS ports across multiple slots.

[0086] Information on DMRS port switching patterns may include information that defines possible DMRS port switching patterns according to the DMRS port switching cycle, and maps a pattern ID to each DMRS port switching pattern so that it can be signaled via DCI or MAC CE. In this case, the DMRS port switching cycle may indicate the cycle of a slot in which all DMRS ports are transmitted. The DMRS port switching cycle may be shorter than the length of a super-slot.

[0087] For example, [Table 3] can represent information about DMRS port switching patterns.

[0088]

[0089] [Table 3] shows the ID (Pattern ID) for the pattern for switching DMRS ports, and shows information about the DMRS assigned to each slot according to the cycle for switching the DMRS ports. [Table 3] shows information about the DMRS assigned to the first to fourth slots when the cycle for switching the DMRS ports is 4 (i.e., this may mean that the number of combined multiple slots is 4).

[0090] The terminal can receive signals by recognizing resources to which DMRS or data signals are allocated for each slot based on information about the DMRS port switching pattern received from the base station.

[0091] According to one embodiment of the present disclosure, in FIG. 8, terminal 1 may receive information about a DMRS port switching pattern from a base station via RRC signaling. In addition, terminal 1 may receive scheduling information for super-slot 5 (i.e., slots 6 to 9) in slot 5 from the base station via DCI. In one example, the scheduling information may include information that the DMRS port switching pattern ID is 0 (i.e., DMRS port switching pattern ID = 0) and the antenna port is 45 (i.e., antenna port = 45).

[0092] Terminal 1 can recognize that the DMRS port switching pattern indicated by DMRS port switching pattern ID 0 is applied to super-slot 5 based on the information about the DMRS port switching pattern in [Table 3]. For example, according to [Table 3], Terminal 1 can recognize that all DMRS ports transmit in the first slot of super-slot 5 (slot 6 in FIG. 8) and no DMRS is transmitted in the second slot of super-slot 5 (slot 7 in FIG. 8). In addition, terminal 1 can recognize that in the third slot of super-slot 5 (slot 8 in FIG. 8) according to [Table 3], only DMRS ports corresponding to CDM group 0 and CDM group 1 are transmitted, and DMRS ports corresponding to CDM group 2 are not transmitted, and in the fourth slot of super-slot 5 (slot 9 in FIG. 8) only DMRS ports corresponding to CDM group 2 are transmitted, and DMRS ports corresponding to CDM group 0 and CDM group 1 are not transmitted. Thereafter, terminal 1 can receive data signals and DMRS of each slot corresponding to the super-slot based on the DMRS pattern switching pattern.

[0093] FIG. 9 illustrates an example of a base station transmitting a DMRS port switching pattern to a terminal when switching DMRS ports in a super-slot according to one embodiment of the present disclosure. Specifically, an example of switching DMRS ports based on RRC signaling is illustrated when the base station transmits 24 DMRS ports in a super-slot structure.

[0094] According to one embodiment of the present disclosure, in FIG. 9, terminal 1 may receive information about a DMRS port switching pattern from a base station via RRC signaling. At this time, the information about the DMRS port switching pattern may represent information of [Table 3]. terminal 1 may receive scheduling information for super-slot 5 (i.e., slots 6 to 9) in slot 5 from the base station via DCI. In one example, the scheduling information may include information that the DMRS port switching pattern ID is 2 (i.e., DMRS port switching pattern ID = 2) and the antenna port is 45 (i.e., antenna port = 45).

[0095] Terminal 1 can recognize that the DMRS port switching pattern indicated by DMRS port switching pattern ID 2 is applied to super-slot 5 based on the information about the DMRS port switching pattern in [Table 4]. [Table 4] shows only the case of DMRS port switching pattern ID 2 in [Table 3].

[0096]

[0097] In one example, terminal 1 can recognize that when the DMRS port switching pattern ID is 2 according to [Table 4], all DMRS ports are transmitted in the first slot of super-slot 5 (slot 6 in FIG. 9) and that not all DMRS ports are transmitted in the second slot of super-slot 5 (slot 7 in FIG. 9). In addition, terminal 1 can recognize that when the DMRS port switching pattern ID is 2 according to [Table 4], only DMRS ports corresponding to CDM group 0, CDM group 1, and CDM group 2 are transmitted in the third slot of super-slot 5 (slot 8 in FIG. 9), and that DMRS ports corresponding to CDM group 3, CDM group 4, and CDM group 5 are not transmitted. Terminal 1 can recognize that only DMRS ports corresponding to CDM group 3, CDM group 4, and CDM group 5 are transmitted in the fourth slot of super-slot 5 (slot 9 in FIG. 9), and DMRS ports corresponding to CDM group 0, CDM group 1, and CDM group 2 are not transmitted.

[0098] Thereafter, terminal 1 can receive data signals and DMRS of each slot in which data signals are transmitted or DMRS is not transmitted through the recognized DMRS ports.

[0099] FIG. 10 illustrates an example of a base station transmitting a signal including a DMRS port switching pattern and an inactive DMRS field to a terminal when switching a DMRS port in a super-slot according to one embodiment of the present disclosure.

[0100] As shown in FIGS. 8 and 9, if a base station informs a terminal of all possible DMRS switching patterns solely through RRC signaling, signaling overhead may occur. FIG. 10 describes an operation for transmitting some of the DMRS switching pattern information not only through RRC signaling but also through DCI or MAC CE to reduce the possibility of signaling overhead.

[0101] According to one embodiment of the present disclosure, in FIG. 10, terminal 1 may receive scheduling information for super-slot 5 (i.e., slots 6 to 9) in slot 5 included in DCI received from a base station. The scheduling information may include information that a DMRS port switching pattern ID is 2 (i.e., DMRS port switching pattern ID = 2) and an antenna port is 30 (i.e., antenna port = 30). At this time, terminal 1 may recognize that 4 DMRS ports are allocated to it through DMRS port switching pattern ID 2 and antenna port 30, and that 6 CDM groups exist in the scheduled PDSCH resource. Terminal 1 may recognize that the DMRS port switching pattern indicated by DMRS port switching pattern ID 2 is applied to super-slot 5. Specifically, terminal 1 may recognize information on DMRS allocation for each slot when the DMS port switching pattern ID of [Table 4] is 2. In one example, terminal 1 can recognize that all DMRS ports are transmitted in the first slot of super-slot 5 (slot 6 in FIG. 10) when the DMRS port switching pattern ID is 2 according to [Table 4], and that none of the DMRS ports are transmitted in the second slot of super-slot 5 (slot 7 in FIG. 10).

[0102] In one example, terminal 1 can recognize that only DMRS ports corresponding to CDM group 0, CDM group 1, and CDM group 2 are transmitted in the third slot of super-slot 5 (slot 8 in FIG. 10) when the DMRS port switching pattern ID in [Table 4] is 2, and DMRS ports corresponding to CDM group 3, CDM group 4, and CDM group 5 are not transmitted. However, if terminal 3 is not scheduled in slot 8 for reasons such as fairness, DMRS may not be transmitted to CDM group 2 corresponding to terminal 3. In this case, terminal 1 can update that no DMRS port is transmitted to CDM group 2 based on the inactive DMRS field value (inactive DMRS = {CDM group 2}) received through DCI or MAC CE. That is, a flexible DMRS port switching configuration is possible in which information about an inactive DMRS field included in DCI or MAC CE overrides some of the information through RRC signaling referenced by the DMRS port switching pattern ID. In this case, the operation of transmitting and receiving some of the information about the DMS port switching pattern using DCI or MAC CE in addition to RRC signaling may be referred to as hybrid signaling. The operation of receiving and applying information about DMRS through hybrid signaling can effectively reduce the overhead occurrence rate compared to the case in which only RRC signaling is used and only DMRS port switching pattern information is based.

[0103] In one example, information about DMRS that can be transmitted from a base station to a terminal via DCI or MAC CE, as well as information about DMRS switching patterns via RRC signaling, may be information about an active DMRS field. Alternatively, information about both an inactive DMRS field and an active DMRS field may be simultaneously announced from the base station to the terminal via DCI or MAC CE.

[0104] Terminal 1 can recognize that only DMRS ports corresponding to CDM group 3, CDM group 4, and CDM group 5 are transmitted in the fourth slot of super-slot 5 (slot 9 in FIG. 9), and DMRS ports corresponding to CDM group 0, CDM group 1, and CDM group 2 are not transmitted.

[0105] Thereafter, terminal 1 can receive data signals and DMRS of each slot in which data signals are transmitted or DMRS is not transmitted through the recognized DMRS ports.

[0106] FIG. 11 illustrates the operation of a base station and a terminal when switching a DMRS port according to one embodiment of the present disclosure.

[0107] Referring to FIG. 11, at step 1110, the base station can identify a DMRS port on which a data signal is transmitted and not a DMRS. In one example, the base station of FIG. 4 can identify a DMRS port on which a data signal is transmitted and not a DMRS in slot 6, in order to transmit scheduling information for slots 5 through 6 to the terminal.

[0108] At step 1120, the base station can transmit DMRS allocation information and scheduling information to the terminal.

[0109] According to one embodiment of the present disclosure, DMRS allocation information may include information regarding a DMRS-empty indicator. The base station may transmit the DMRS-empty indicator and scheduling information to the UE via DCI or MAC CE. The DMRS-empty indicator may be an indicator indicating that no DMRS is transmitted on the DMRS port associated with the UE, and thus, the UE should reuse the DMRS it last received.

[0110] For example, in FIG. 4, when the DMRS-empty indicator is 1, a data signal is transmitted instead of a DMRS transmitted on the resources allocated to the terminal, so it can be instructed to reuse the last acquired DMRS ports. When the DMRS-empty indicator received from the base station is 1, the terminal can demodulate a data signal for a PDSCH scheduled by DCI or a data signal for a PDSCH indicated by MAC CE using the last acquired DMRS port. Referring to FIG. 4, slot 5 is allocated to CDM group 1, CDM group 2, and CDM group 3 for terminals 1 to 3, respectively, and DMRS ports corresponding to CDM group 1, CDM group 2, and CDM group 3 can be transmitted. For example, when a base station transmits DCI to terminal 1 to schedule slots 5 through 6, the DCI may include information about antenna ports (e.g., information that the antenna port is 45) as well as information that the DMRS-empty indicator is 1 to indicate that there are no DMRS-allocated resources in slot 6. Based on the information that the DMRS-empty indicator is 1 for slot 6 from the base station, the terminal can decode a data signal for the PDSCH using the DMRS port it acquired last.

[0111] According to one embodiment of the present disclosure, DMRS allocation information may include information on an inactive DMRS field value or an active DMRS field value. The base station may transmit the inactive DMRS field value or the active DMRS field value to the terminal via DCI or MAC CE. The inactive DMRS field value may indicate information on a CDM group to which no DMRS is transmitted among CDM groups to which no terminal is assigned. The active DMRS field value may indicate information on a CDM group to which a DMRS is transmitted among CDM groups to which no terminal is assigned.

[0112] In one example, when a base station transmits DCI to terminal 1 to schedule slot 6 from slot 5 in FIG. 6, the DCI may include information about the antenna port (e.g., information that the antenna port is 45) as well as an inactive DMRS field indicating that DMRS is not transmitted on resources corresponding to CDM group 2 (e.g., inactive DMRS = {CDM group 2}). In this case, the base station may also transmit the DCI by including an active DMRS field indicating that DMRS is transmitted on resources corresponding to CDM group 1 due to antenna port switching (e.g., active DMRS = {CDM group 1}).

[0113] According to one embodiment of the present disclosure, DMRS allocation information may include information about an interference reuse field value. The base station may transmit the interference reuse field value to the terminal via DCI or MAC CE. The interference reuse field value may indicate information about the ID of the CDM group for which the interference information last measured by the base station is valid.

[0114] In one example, terminal 1 in FIG. 7 can receive information from the base station that interference information of CDM group 2 in slot 6 is valid (e.g., interference reuse = {CDM group 2}) through DCI or MAC CE.

[0115] According to one embodiment of the present disclosure, a base station may transmit information about multiple DMRS port switching patterns to a terminal via RRC signaling. The information about the DMRS port switching patterns may indicate the pattern in which DMRS ports are switched for multiple slots within a super-slot structure.

[0116] In one example, in FIG. 8, terminal 1 may receive information about a DMRS port switching pattern from a base station via RRC signaling. Additionally, terminal 1 may receive scheduling information for super-slot 5 (i.e., slots 6 to 9) in slot 5 from the base station via DCI. For example, the scheduling information may include information that the DMRS port switching pattern ID is 0 (i.e., DMRS port switching pattern ID = 0) and the antenna port is 45 (i.e., antenna port = 45).

[0117] According to one embodiment of the present disclosure, a base station may transmit information about a DMRS switching pattern via RRC signaling and DCI or MAC CE. For example, in FIG. 10, the base station may transmit DMRS port switching pattern information to terminal 1 via RRC signaling, and additionally transmit an inactive DMRS field value via DCI or MAC CE. In addition to the inactive DMRS field value, an active DMRS field value may also be transmitted.

[0118] At step 1130, the terminal can identify a data signal for a physical downlink shared channel (PDSCH) and a DMRS port to which the DMRS is allocated based on DMRS allocation information received from the base station.

[0119] The DMRS allocation information that the terminal receives from the base station through DCI or MAC CE may be one of the DMS-empty indicator transmitted by the base station in step 1120, the inactive DMRS field value / active DMRS field value, the interference reuse feed value, or information indicating a DMRS port switching pattern.

[0120] According to one embodiment of the present disclosure, when a terminal receives information from a base station that a DMRS-empty indicator is 1, the terminal may demodulate a data signal for a physical downlink shared channel (PDSCH) scheduled by a DCI or a data signal for a PDSCH indicated by a MAC CE using the last acquired DMRS port. For example, referring to FIG. 4, in slot 5, terminals 1 to 3 may be assigned to CDM group 1, CDM group 2, and CDM group 3, respectively, and DMRS ports corresponding to CDM group 1, CDM group 2, and CDM group 3 may be transmitted. When the base station transmits DCI for scheduling from slot 5 to slot 6 to terminal 1, the DCI may include information that a DMRS-empty indicator is 1 to indicate that there is no resource allocated to a DMRS in slot 6, in addition to information about an antenna port (e.g., information that the antenna port is 45). Terminal 1 can decode a data signal for the PDSCH using the DMRS port that it last acquired based on the information that the DMRS-empty indicator for slot 6 from the base station is 1.

[0121] According to one embodiment of the present disclosure, when a terminal receives information from a base station that a DMRS-empty indicator is 0, the terminal may indicate that a DMRS is transmitted on a DMRS port corresponding to a CDM group to which the terminal is assigned, and thus, the last acquired DMRS port does not need to be reused. For example, in FIG. 4, when the base station transmits DCI for scheduling slot 7 to terminal 1 in slot 6, the DCI may include information about an antenna port as well as information about a DMRS-empty indicator of 0 to indicate that a DMRS is transmitted on a DMRS port corresponding to CDM group 0 associated with terminal 1 in slot 7. Terminal 1 may receive a DMRS based on the information from the base station that the DMRS-empty indicator for slot 7 is 0.

[0122] According to one embodiment of the present disclosure, when a terminal receives information about an inactive DMRS field or an active DMRS field from a base station, the terminal can identify a resource on which a data signal is transmitted without transmitting a DMRS.

[0123] According to one embodiment of the present disclosure, when a terminal receives information about an interference reuse field value from a base station, the terminal can reuse interference information for CDM group 2 indicated by the interference reuse field value.

[0124] According to one embodiment of the present disclosure, when a terminal receives information on a DMRS port switching pattern from a base station via RRC signaling, the terminal can identify a DMRS port switching pattern that is mapped to information indicating a DMRS port switching pattern received via DCI or MAC CE.

[0125] At step 1140, the base station can transmit DMRS and data signals to the terminal. The terminal can receive data signals and DMRS for the PDSCH based on the identified DMRS port.

[0126] At step 1150, the terminal can demodulate the PDSCH based on the received DMRS and data signals. The terminal can calculate a covariance matrix based on the received data signal. Furthermore, the terminal can estimate the channel based on the received DMRS signal. The terminal can receive the data signal by calculating a minimum mean square error (MMSE)-interference rejection combining (IRC) receiver based on the covariance matrix and the estimated channel. The matrix of the MMSE-IRC receiver can mean a covariance matrix according to the MMSE channel estimation. The matrix of the MMSE-IRC receiver can be calculated according to the formula of [Table 2] described above.

[0127] FIG. 12 illustrates the operation of a terminal according to one embodiment of the present disclosure.

[0128] In step 1210 of FIG. 12, the terminal may receive at least one of DCI or MAC CE including DMRS allocation information and scheduling information from the base station.

[0129] According to one embodiment of the present disclosure, DMRS allocation information may include information regarding a DMRS-empty indicator. The base station may transmit the DMRS-empty indicator and scheduling information to the terminal via DCI or MAC CE. The DMRS-empty indicator may be an indicator indicating that no DMRS is being transmitted, and thus, the last acquired DMRS should be reused.

[0130] For example, in FIG. 4, when the DMRS-empty indicator is 1, a data signal is transmitted instead of a DMRS transmitted on the resources allocated to the terminal, so it can be instructed to reuse the last acquired DMRS ports. When the DMRS-empty indicator received from the base station is 1, the terminal can demodulate a data signal for a PDSCH scheduled by DCI or a data signal for a PDSCH indicated by MAC CE using the last acquired DMRS port. Referring to FIG. 4, slot 5 is allocated to CDM group 1, CDM group 2, and CDM group 3 for terminals 1 to 3, respectively, and DMRS ports corresponding to CDM group 1, CDM group 2, and CDM group 3 can be transmitted. For example, when a base station transmits DCI to terminal 1 to schedule slots 5 through 6, the DCI may include information about antenna ports (e.g., information that the antenna port is 45) as well as information that the DMRS-empty indicator is 1 to indicate that there are no DMRS-allocated resources in slot 6. Based on the information that the DMRS-empty indicator is 1 for slot 6 from the base station, the terminal can decode a data signal for the PDSCH using the DMRS port it acquired last.

[0131] According to one embodiment of the present disclosure, DMRS allocation information may include information on an inactive DMRS field value or an active DMRS field value. The base station may transmit the inactive DMRS field value or the active DMRS field value to the terminal via DCI or MAC CE. The inactive DMRS field value may indicate information on a CDM group to which no DMRS is transmitted among CDM groups to which no terminal is assigned. The active DMRS field value may indicate information on a CDM group to which a DMRS is transmitted among CDM groups to which no terminal is assigned.

[0132] In one example, when a base station transmits DCI to terminal 1 to schedule slot 6 from slot 5 in FIG. 6, the DCI may include information about the antenna port (e.g., information that the antenna port is 45) as well as an inactive DMRS field indicating that DMRS is not transmitted on resources corresponding to CDM group 2 (e.g., inactive DMRS = {CDM group 2}). In this case, the base station may also transmit the DCI by including an active DMRS field indicating that DMRS is transmitted on resources corresponding to CDM group 1 due to antenna port switching (e.g., active DMRS = {CDM group 1}).

[0133] According to one embodiment of the present disclosure, DMRS allocation information may include information about an interference reuse field value. The base station may transmit the interference reuse field value to the terminal via DCI or MAC CE. The interference reuse field value may indicate information about the ID of the CDM group for which the interference information last measured by the base station is valid.

[0134] In one example, terminal 1 in FIG. 7 can receive information from the base station that interference information of CDM group 2 in slot 6 is valid (e.g., interference reuse = {CDM group 2}) through DCI or MAC CE.

[0135] According to one embodiment of the present disclosure, a base station may transmit information about multiple DMRS port switching patterns to a terminal via RRC signaling. The information about the DMRS port switching patterns may indicate the pattern in which DMRS ports are switched for multiple slots within a super-slot structure.

[0136] In one example, in FIG. 8, terminal 1 may receive information about a DMRS port switching pattern from a base station via RRC signaling. Additionally, terminal 1 may receive scheduling information for super-slot 5 (i.e., slots 6 to 9) in slot 5 from the base station via DCI. For example, the scheduling information may include information that the DMRS port switching pattern ID is 0 (i.e., DMRS port switching pattern ID = 0) and the antenna port is 45 (i.e., antenna port = 45).

[0137] According to one embodiment of the present disclosure, a base station may transmit information about a DMRS switching pattern via RRC signaling and DCI or MAC CE. For example, in FIG. 10, the base station may transmit DMRS port switching pattern information to terminal 1 via RRC signaling, and additionally transmit an inactive DMRS field value via DCI or MAC CE. In addition to the inactive DMRS field value, an active DMRS field value may also be transmitted.

[0138] At step 1220, the terminal can identify a data signal for a physical downlink shared channel (PDSCH) and a DMRS port to which the DMRS is allocated based on DMRS allocation information received from the base station.

[0139] The DMRS allocation information that the terminal receives from the base station through DCI or MAC CE may be one of the DMS-empty indicator received from the base station in step 1210, the inactive DMRS field value / active DMRS field value, the interference reuse feed value, or information indicating a DMRS port switching pattern.

[0140] According to one embodiment of the present disclosure, when a terminal receives information from a base station that a DMRS-empty indicator is 1, the terminal may demodulate a data signal for a physical downlink shared channel (PDSCH) scheduled by a DCI or a data signal for a PDSCH indicated by a MAC CE using the last acquired DMRS port. For example, referring to FIG. 4, in slot 5, terminals 1 to 3 may be assigned to CDM group 1, CDM group 2, and CDM group 3, respectively, and DMRS ports corresponding to CDM group 1, CDM group 2, and CDM group 3 may be transmitted. When the base station transmits DCI for scheduling from slot 5 to slot 6 to terminal 1, the DCI may include information that a DMRS-empty indicator is 1 to indicate that there is no resource allocated to a DMRS in slot 6, in addition to information about an antenna port (e.g., information that the antenna port is 45). Terminal 1 can decode a data signal for the PDSCH using the DMRS port that it last acquired based on the information that the DMRS-empty indicator for slot 6 from the base station is 1.

[0141] According to one embodiment of the present disclosure, when a terminal receives information from a base station that a DMRS-empty indicator is 0, the terminal may indicate that a DMRS is transmitted on a DMRS port corresponding to a CDM group to which the terminal is assigned, and thus, the last acquired DMRS port does not need to be reused. For example, in FIG. 4, when the base station transmits DCI for scheduling slot 7 to terminal 1 in slot 6, the DCI may include information about an antenna port as well as information about a DMRS-empty indicator of 0 to indicate that a DMRS is transmitted on a DMRS port corresponding to CDM group 0 associated with terminal 1 in slot 7. Terminal 1 may receive a DMRS based on the information from the base station that the DMRS-empty indicator for slot 7 is 0.

[0142] According to one embodiment of the present disclosure, when a terminal receives information about an inactive DMRS field or an active DMRS field from a base station, the terminal can identify a resource on which a data signal is transmitted without transmitting a DMRS.

[0143] According to one embodiment of the present disclosure, when a terminal receives information about an interference reuse field value from a base station, the terminal can reuse interference information for CDM group 2 indicated by the interference reuse field value.

[0144] According to one embodiment of the present disclosure, when a terminal receives information on a DMRS port switching pattern from a base station via RRC signaling, the terminal can identify a DMRS port switching pattern that is mapped to information indicating a DMRS port switching pattern received via DCI or MAC CE.

[0145] At step 1230, the terminal can receive data signals and DMRS for the PDSCH based on the identified DMRS port.

[0146] At step 1240, the terminal can demodulate the PDSCH based on the received DMRS and data signals. The terminal can calculate a covariance matrix based on the received data signal. Furthermore, the terminal can estimate the channel based on the received DMRS signal. The terminal can receive the data signal by calculating a minimum mean square error (MMSE)-interference rejection combining (IRC) receiver based on the covariance matrix and the estimated channel. The matrix of the MMSE-IRC receiver can mean a covariance matrix according to the MMSE channel estimation. The matrix of the MMSE-IRC receiver can be calculated according to the formula of [Table 2] described above.

[0147] FIG. 13 illustrates the operation of a base station according to one embodiment of the present disclosure.

[0148] Referring to FIG. 13, at step 1310, the base station can identify a DMRS port on which a data signal is transmitted and not a DMRS. In one example, the base station of FIG. 4 can identify a DMRS port on which a data signal is transmitted and not a DMRS in slot 6, in order to transmit scheduling information for slots 5 through 6 to the terminal.

[0149] At step 1320, the base station can transmit DMRS allocation information and scheduling information to the terminal.

[0150] According to one embodiment of the present disclosure, DMRS allocation information may include information regarding a DMRS-empty indicator. The base station may transmit the DMRS-empty indicator and scheduling information to the terminal via DCI or MAC CE. The DMRS-empty indicator may be an indicator indicating that no DMRS is being transmitted, and thus, the last acquired DMRS should be reused.

[0151] For example, in FIG. 4, when the DMRS-empty indicator is 1, a data signal is transmitted instead of a DMRS transmitted on the resources allocated to the terminal, so it can be instructed to reuse the last acquired DMRS ports. When the DMRS-empty indicator received from the base station is 1, the terminal can demodulate a data signal for a PDSCH scheduled by DCI or a data signal for a PDSCH indicated by MAC CE using the last acquired DMRS port. Referring to FIG. 4, slot 5 is allocated to CDM group 1, CDM group 2, and CDM group 3 for terminals 1 to 3, respectively, and DMRS ports corresponding to CDM group 1, CDM group 2, and CDM group 3 can be transmitted. For example, when a base station transmits DCI to terminal 1 to schedule slots 5 through 6, the DCI may include information about antenna ports (e.g., information that the antenna port is 45) as well as information that the DMRS-empty indicator is 1 to indicate that there are no DMRS-allocated resources in slot 6. Based on the information that the DMRS-empty indicator is 1 for slot 6 from the base station, the terminal can decode a data signal for the PDSCH using the DMRS port it acquired last.

[0152] According to one embodiment of the present disclosure, DMRS allocation information may include information on an inactive DMRS field value or an active DMRS field value. The base station may transmit the inactive DMRS field value or the active DMRS field value to the terminal via DCI or MAC CE. The inactive DMRS field value may indicate information on a CDM group to which no DMRS is transmitted among CDM groups to which no terminal is assigned. The active DMRS field value may indicate information on a CDM group to which a DMRS is transmitted among CDM groups to which no terminal is assigned.

[0153] In one example, when a base station transmits DCI to terminal 1 to schedule slot 6 from slot 5 in FIG. 6, the DCI may include information about the antenna port (e.g., information that the antenna port is 45) as well as an inactive DMRS field indicating that DMRS is not transmitted on resources corresponding to CDM group 2 (e.g., inactive DMRS = {CDM group 2}). In this case, the base station may also transmit the DCI by including an active DMRS field indicating that DMRS is transmitted on resources corresponding to CDM group 1 due to antenna port switching (e.g., active DMRS = {CDM group 1}).

[0154] According to one embodiment of the present disclosure, DMRS allocation information may include information about an interference reuse field value. The base station may transmit the interference reuse field value to the terminal via DCI or MAC CE. The interference reuse field value may indicate information about the ID of the CDM group for which the interference information last measured by the base station is valid.

[0155] In one example, terminal 1 in FIG. 7 can receive information from the base station that interference information of CDM group 2 in slot 6 is valid (e.g., interference reuse = {CDM group 2}) through DCI or MAC CE.

[0156] According to one embodiment of the present disclosure, a base station may transmit information about multiple DMRS port switching patterns to a terminal via RRC signaling. The information about the DMRS port switching patterns may indicate the pattern in which DMRS ports are switched for multiple slots within a super-slot structure.

[0157] In one example, in FIG. 8, terminal 1 may receive information about a DMRS port switching pattern from a base station via RRC signaling. Additionally, terminal 1 may receive scheduling information for super-slot 5 (i.e., slots 6 to 9) in slot 5 from the base station via DCI. For example, the scheduling information may include information that the DMRS port switching pattern ID is 0 (i.e., DMRS port switching pattern ID = 0) and the antenna port is 45 (i.e., antenna port = 45).

[0158] According to one embodiment of the present disclosure, a base station may transmit information about a DMRS switching pattern via RRC signaling and DCI or MAC CE. For example, in FIG. 10, the base station may transmit DMRS port switching pattern information to terminal 1 via RRC signaling, and additionally transmit an inactive DMRS field value via DCI or MAC CE. In addition to the inactive DMRS field value, an active DMRS field value may also be transmitted.

[0159] FIG. 14 illustrates the structure of a terminal (1400) according to various embodiments of the present disclosure.

[0160] The configuration illustrated in Fig. 14 can be understood as the configuration of a terminal (1400). Terms such as "... unit" and "... device" used hereinafter mean a unit that processes at least one function or operation, and this can be implemented by hardware, software, or a combination of hardware and software.

[0161] Referring to FIG. 14, the terminal (1400) includes a communication unit (1410), a storage unit (1420), and a control unit (1430).

[0162] The communication unit (1410) performs functions for transmitting and receiving signals via a wireless channel. For example, the communication unit (1410) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the communication unit (1410) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the communication unit (1410) restores a reception bit stream by demodulating and decoding the baseband signal. In addition, the communication unit (1410) upconverts a baseband signal to an RF band signal and transmits it through an antenna, and downconverts an RF band signal received through the antenna to a baseband signal. For example, the communication unit (1410) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0163] In addition, the communication unit (1410) may include a plurality of transmission and reception paths. Furthermore, the communication unit (1410) may include an antenna unit. The communication unit (1410) may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit (1410) may be composed of digital circuits and analog circuits (e.g., radio frequency integrated circuits (RFIC)). Here, the digital circuits and analog circuits may be implemented in a single package. In addition, the communication unit (1410) may include a plurality of RF chains. The communication unit (1410) may perform beamforming. The communication unit (1410) may apply beamforming weights to a signal to be transmitted and received in order to impart directionality according to the settings of the control unit (1430). According to one embodiment, the communication unit (1410) may include an RF (radio frequency) block (or RF unit). The RF block may include first RF circuitry associated with the antenna and second RF circuitry associated with baseband processing. The first RF circuitry may be referred to as RF-A (antenna). The second RF circuitry may be referred to as RF-B (baseband).

[0164] Additionally, the communication unit (1410) can transmit and receive signals. To this end, the communication unit (1410) may include at least one transceiver. The communication unit (1410) may receive downlink signals. The downlink signal may include a synchronization signal (SS), a reference signal (RS) (e.g., demodulation (DM)-RS, phase tracking reference signal (PTRS), system information (e.g., MIB, SIB, remaining system information (RMSI), other system information (OSI)), a configuration message, control information, or downlink data, etc.). In addition, the communication unit (1110) may transmit an uplink signal. The uplink signal may include a random access related signal (e.g., a random access preamble (RAP) (or Msg1 (message 1) or Msg3 (message 3)), a reference signal (e.g., a sounding reference signal (SRS), DMRS, PTRS), or a power headroom report (PHR).

[0165] Additionally, the communication unit (1410) may include different communication modules to process signals of different frequency bands. Furthermore, the communication unit (1410) may include multiple communication modules to support multiple different wireless access technologies. For example, different wireless access technologies may include Bluetooth low energy (BLE), Wireless Fidelity (Wi-Fi), WiFi Gigabyte (WiGig), cellular networks (e.g., Long Term Evolution (LTE), new radio (NR), etc.). In addition, different frequency bands may include super high frequency (SHF) (e.g., 2.5 GHz, 5 GHz) bands, millimeter wave (mm wave) (e.g., 38 GHz, 60 GHz, etc.) bands. In addition, the communication unit (1510) may use the same type of wireless access technology on different frequency bands (e.g., unlicensed bands for licensed assisted access (LAA), citizens broadband radio service (CBRS) (e.g., 3.5 GHz)).

[0166] The communication unit (1410) transmits and receives signals as described above. Accordingly, all or part of the communication unit (1410) may be referred to as a "transmitter," a "receiver," or a "transmitting and receiving unit." Furthermore, in the following description, transmission and reception performed via a wireless channel are used to mean processing performed by the communication unit (1410) as described above.

[0167] The storage unit (1420) stores data such as basic programs, application programs, and setting information for the operation of the terminal (1400). The storage unit (1420) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. In addition, the storage unit (1420) provides stored data upon request from the control unit (1430).

[0168] The control unit (1430) controls the overall operations of the terminal (1400). For example, the control unit (1430) transmits and receives signals through the communication unit (1410). In addition, the control unit (1430) records and reads data in the storage unit (1420). In addition, the control unit (1530) can perform the functions of the protocol stack required by the communication standard. To this end, the control unit (1430) may include at least one processor. The control unit (1430) may include at least one processor or microprocessor, or may be a part of a processor. In addition, a part of the communication unit (1410) and the control unit (1430) may be referred to as a CP. The control unit (1430) may include various modules for performing communication. According to various embodiments, the control unit (1430) may control the terminal to perform operations according to various embodiments.

[0169] FIG. 15 illustrates the structure of a base station (1500) according to various embodiments of the present disclosure.

[0170] Referring to FIG. 15, the base station (1500) includes a communication unit (1510), a storage unit (1520), and a control unit (1530).

[0171] The communication unit (1510) performs functions for transmitting and receiving signals via a wireless channel. For example, the communication unit (1510) performs a conversion function between a baseband signal and a bit stream according to the physical layer specifications of the system. For example, when transmitting data, the communication unit (1510) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the communication unit (1510) restores a reception bit stream by demodulating and decoding the baseband signal. In addition, the communication unit (1510) upconverts a baseband signal into an RF (radio frequency) band signal and transmits it through an antenna, and downconverts an RF band signal received through the antenna into a baseband signal.

[0172] To this end, the communication unit (1510) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a digital to analog convertor (DAC), an analog to digital convertor (ADC), etc. In addition, the communication unit (1510) may include a plurality of transmission and reception paths. Furthermore, the communication unit (1510) may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit (1510) may be composed of a digital unit and an analog unit, and the analog unit may be composed of a plurality of sub-units according to operating power, operating frequency, etc.

[0173] The communication unit (1510) can transmit and receive signals. To this end, the communication unit (1510) may include at least one transceiver. For example, the communication unit (1510) may transmit a synchronization signal, a reference signal, system information, messages, control information, or data. In addition, the communication unit (1510) may perform beamforming.

[0174] The communication unit (1510) transmits and receives signals as described above. Accordingly, all or part of the communication unit (1510) may be referred to as a "transmitter," a "receiver," or a "transmitting and receiving unit." Furthermore, in the following description, transmission and reception performed via a wireless channel are used to mean processing performed by the communication unit (1510) as described above.

[0175] The storage unit (1520) stores data such as basic programs, application programs, and setting information for the operation of the base station. The storage unit (1520) may include memory. The storage unit (1520) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. In addition, the storage unit (1520) provides stored data upon request from the control unit (1530).

[0176] The control unit (1530) controls the overall operations of the base station (1500). For example, the control unit (1530) transmits and receives signals through the communication unit (1510). In addition, the control unit (1530) records and reads data from the storage unit (1520). In addition, the control unit (1530) can perform the functions of the protocol stack required by the communication standard. To this end, the control unit (1530) can include at least one processor.

[0177] The configuration of the base station (1500) illustrated in FIG. 15 is merely an example of a base station, and examples of base stations performing various embodiments of the present disclosure are not limited to the configuration illustrated in FIG. 15. That is, some configurations may be added, deleted, or changed according to various embodiments.

[0178] Although the base station (1500) is described as a single entity in FIG. 15, the present disclosure is not limited thereto. The base station (1500) according to various embodiments of the present disclosure may be implemented to form an access network having not only an integrated deployment but also a distributed deployment. According to one embodiment, the base station may be divided into a central unit (CU) and a digital unit (DU), and the CU may be implemented to perform upper layer functions (e.g., packet data convergence protocol (RRC) PDCP) and the DU may be implemented to perform lower layer functions (e.g., medium access control (MAC), physical (PHY)). The DU of the base station may form beam coverage on a wireless channel.

[0179] Meanwhile, the embodiments of the present invention disclosed in this specification and drawings are merely specific examples presented to easily explain the technical content of the present invention and facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. In other words, it will be apparent to those skilled in the art that other modifications based on the technical concept of the present invention are possible. Furthermore, the above-described embodiments can be combined and operated as needed.

[0180] As described above, a method performed by a user equipment in a wireless communication system according to various embodiments disclosed in the present document may include the steps of receiving, from a base station, at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE), identifying a DMRS port to which a data signal and a DMRS for a physical downlink shared channel (PDSCH) are allocated based on the DMRS allocation information, receiving the data signal and the DMRS based on the identified DMRS port, and demodulating the PDSCH based on the DMRS and the data signal.

[0181] According to various embodiments disclosed in this document, DMRS allocation information may include a DMRS-empty indicator, and the DMRS-empty indicator may indicate a DMRS port to be reused.

[0182] According to various embodiments disclosed in this document, the DMRS allocation information includes at least one of an inactive DMRS field value or an active DMRS field value, and the inactive DMRS field value may indicate information about a code division multiplexing (CDM) group in which the DMRS is not transmitted among the CDM groups to which the DMRS is allocated.

[0183] According to various embodiments disclosed in this document, the DMRS allocation information includes an interference reuse field value, and the interference reuse field value may include information about a CDM group for which interference information in a first slot is valid in a second slot.

[0184] According to various embodiments disclosed in the present document, DMRS allocation information includes information indicating a DMRS port switching pattern, and the method may include a step of receiving DMRS port switching pattern information from a base station through RRC (radio resource control) signaling, and a step of identifying a DMRS port switching pattern mapped to information indicating a DMRS switching pattern among the DMRS port switching pattern information.

[0185] As described above, a user equipment according to various embodiments disclosed in the present document may include a transceiver and a controller coupled with the transceiver, and the controller may be configured to receive, from a base station, at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE), identify a DMRS port to which a data signal and a DMRS for a physical downlink shared channel (PDSCH) are allocated based on the DMRS allocation information, receive the data signal and the DMRS based on the identified DMRS port, and demodulate the PDSCH based on the DMRS and the data signal.

[0186] According to various embodiments disclosed in this document, MRS allocation information includes information indicating a DMRS port switching pattern, and a controller may be configured to receive DMRS port switching pattern information from a base station through RRC (radio resource control) signaling, and identify a DMRS port switching pattern mapped to information indicating a DMRS switching pattern among the DMRS port switching pattern information.

[0187] As described above, a method performed by a base station in a wireless communication system according to various embodiments disclosed in the present document includes a step of identifying a DMRS port on which a data signal is transmitted and a demodulation reference signal (DMRS) is not transmitted, and a step of transmitting at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE) to a user equipment (UE), wherein the DMRS allocation information can be used by the user equipment to identify a DMRS port to which a data signal and DMRS for a physical downlink shared channel (PDSCH) are allocated.

[0188] According to various embodiments disclosed in the present document, a method includes a step of transmitting DMRS port switching pattern information to a terminal via RRC (radio resource control) signaling, wherein the DMRS allocation information includes information indicating a DMRS port switching pattern, and the information indicating the DMRS port switching pattern can be used by the terminal to identify a DMRS port switching pattern that is mapped to the information indicating the DMRS switching pattern among the DMRS port switching pattern information.

[0189] As described above, in a wireless communication system according to various embodiments disclosed in the present document, a base station includes a transceiver and a controller coupled to the transceiver, and the controller is configured to identify a DMRS port on which a data signal is transmitted but a demodulation reference signal (DMRS) is not transmitted, and to transmit, to a user equipment (UE), at least one of downlink control information (DCI) including demodulation reference signal (DMRS) allocation information and scheduling information or a medium access control (MAC) control element (CE), wherein the DMRS allocation information can be used by the user equipment to identify a DMRS port on which a data signal and a DMRS for a physical downlink shared channel (PDSCH) are allocated.

[0190] According to various embodiments disclosed in this document, a controller is configured to transmit DMRS port switching pattern information to a terminal via RRC (radio resource control) signaling, wherein the DMRS allocation information includes information indicating a DMRS port switching pattern, and the information indicating the DMRS port switching pattern can be used by the terminal to identify a DMRS port switching pattern that is mapped to the information indicating the DMRS switching pattern among the DMRS port switching pattern information.

Claims

1. In a method performed by a terminal (user equipment) in a wireless communication system, A step of receiving at least one of downlink control information (DCI), medium access control (MAC) control element (CE), or radio resource control (RRC) signaling including demodulation reference signal (DMRS) allocation information and scheduling information from a base station; A step of identifying a data signal for a PDSCH (physical downlink shared channel) and a DMRS port to which the DMRS is allocated based on the above DMRS allocation information; A step of receiving the data signal and the DMRS based on the identified DMRS port; and A method comprising a step of demodulating the PDSCH based on the DMRS and the data signal.

2. In claim 1, The above DMRS allocation information includes a DMRS-empty indicator, The above DMRS-empty indicator is used to identify whether the DMRS is transmitted on the scheduled PDSCH, The above DMRS-empty indicator indicates reuse of a DMRS port channel allocated for transmission of a previous PDSCH.

3. In claim 1, The above DMRS allocation information includes at least one of an inactive DMRS field value or an active DMRS field value, The above inactive DMRS field value indicates information about a code division multiplexing (CDM) group to which a DMRS is assigned and to which a DMRS is not transmitted. The above active DMRS field value indicates information about the CDM group to which the DMRS is transmitted among the CDM groups to which the DMRS is assigned. A method in which a DMRS transmitted on a scheduled PDSCH is identified based on the inactive DMRS field value or the active DMRS field value and a specific antenna port value indicated by the DCI.

4. In claim 1, The above DMRS allocation information includes an interference reuse field value, A method wherein the above interference reuse field value includes information about a CDM group for which interference information in the first slot is valid in the second slot.

5. In claim 1, the DMRS allocation information includes information indicating a DMRS port switching pattern, and the method comprises: A step of receiving DMRS port switching pattern information from the base station through the RRC signaling; A step of receiving information indicating the DMRS switching pattern among the DMRS port switching pattern information from the base station through the DCI or the MAC-CE; and A step of identifying a DMRS port switching pattern mapped to information indicating the above DMRS switching pattern, The above DMRS port switching pattern information includes a plurality of switching patterns indicating inactive DMRS information or active DMRS information in a plurality of slots, A method in which the PDSCH is demodulated based on the identified DMRS port switching pattern.

6. In a wireless communication system, in the terminal (user equipment), transceiver; and including a controller coupled with the above transmitter and receiver, The above controller, Receive at least one of downlink control information (DCI), medium access control (MAC) control element (CE), or radio resource control (RRC) signaling including demodulation reference signal (DMRS) allocation information and scheduling information from a base station, Based on the above DMRS allocation information, a data signal for a PDSCH (physical downlink shared channel) and a DMRS port to which the DMRS is allocated are identified, Receive the data signal and the DMRS based on the identified DMRS port, A terminal configured to demodulate the PDSCH based on the DMRS and the data signal.

7. In claim 6, The above DMRS allocation information includes a DMRS-empty indicator, The above DMRS-empty indicator is used to identify whether the DMRS is transmitted on the scheduled PDSCH, The above DMRS-empty indicator indicates the reuse of a DMRS port channel allocated for transmission of a previous PDSCH.

8. In claim 6, The above DMRS allocation information includes at least one of an inactive DMRS field value or an active DMRS field value, The above inactive DMRS field value indicates information about a code division multiplexing (CDM) group to which a DMRS is assigned, and a CDM group in which a DMRS is not transmitted. The above active DMRS field value indicates information about the CDM group to which the DMRS is transmitted among the CDM groups to which the DMRS is assigned. A terminal in which a DMRS transmitted on a scheduled PDSCH is identified based on the inactive DMRS field value or the active DMRS field value and a specific antenna port value indicated by the DCI.

9. In a method performed by a base station in a wireless communication system, A step of identifying a DMRS port through which a demodulation reference signal (DMRS) is not transmitted and a data signal is transmitted; and A step of transmitting, to a user equipment, at least one of downlink control information (DCI), medium access control (MAC) control element (CE), or radio resource control (RRC) signaling, including demodulation reference signal (DMRS) allocation information and scheduling information, A method in which the above DMRS allocation information is used by the terminal to identify a data signal for a PDSCH (physical downlink shared channel) and a DMRS port to which the DMRS is allocated.

10. In claim 9, The above DMRS allocation information includes a DMRS-empty indicator, The above DMRS-empty indicator indicates reuse of a DMRS port channel allocated for transmission of a previous PDSCH.

11. In claim 9, The above DMRS allocation information includes at least one of an inactive DMRS field value or an active DMRS field value, The above inactive DMRS field value indicates information about a code division multiplexing (CDM) group to which a DMRS is assigned and to which a DMRS is not transmitted. The above active DMRS field value indicates information about the CDM group to which the DMRS is transmitted among the CDM groups to which the DMRS is assigned. A method in which a DMRS transmitted on a scheduled PDSCH is associated with a specific antenna port value indicated by the DCI and an inactive DMRS field value or an active DMRS field value.

12. In claim 9, The above DMRS allocation information includes an interference reuse field value, A method wherein the above interference reuse field value includes information about a CDM group for which interference information in the first slot is valid in the second slot.

13. In claim 9, the method comprises: A step of transmitting DMRS port switching pattern information to the terminal through the RRC signaling; and A step of transmitting information indicating the DMRS switching pattern among the DMRS port switching pattern information to the terminal through the DCI or the MAC-CE, The above DMRS allocation information includes information indicating a DMRS port switching pattern, The information indicating the DMRS port switching pattern is used by the terminal to identify a DMRS port switching pattern that is mapped to the information indicating the DMRS switching pattern among the DMRS port switching pattern information, A method wherein the DMRS port switching pattern information includes a plurality of switching patterns indicating inactive DMRS information or active DMRS information in a plurality of slots.

14. In a base station in a wireless communication system, transceiver; and including a controller coupled with the above transmitter and receiver, The above controller, Identify a DMRS port where a data signal is transmitted without transmitting a demodulation reference signal (DMRS), It is configured to transmit at least one of downlink control information (DCI), medium access control (MAC) control element (CE), or radio resource control (RRC) signaling including demodulation reference signal (DMRS) allocation information and scheduling information to a terminal (user equipment), The above DMRS allocation information is used by the terminal to identify a data signal for a PDSCH (physical downlink shared channel) and a DMRS port to which the DMRS is allocated.

15. In claim 14, The above DMRS allocation information includes a DMRS-empty indicator, The above DMRS-empty indicator indicates the reuse of a DMRS port channel allocated for transmission of a previous PDSCH.

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