Method and device for 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. More specifically, a method performed by a terminal in a wireless communication system comprises the steps of: providing information related to a reception antenna port of the terminal to a base station; transmitting, to the base station, capability information including information on a maximum number of demodulation reference signal (DMRS) groups that the terminal can support; receiving, from the base station, configuration information including information on a number of DMRS groups configured for the terminal; and receiving, from the base station, at least one DMRS corresponding to the number of DMRS groups based on the configuration information through a different reception antenna port of the terminal associated with each of the DMRS groups, wherein DMRS ports, assigned with the same or different port indices, are configured for each of the DMRS groups, and different initialization sequences for generating a DMRS sequence may be applied to each of the DMRS groups.

Description

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

[0001] The present disclosure relates generally to wireless communication systems, and more particularly to devices and methods for a terminal to receive a downlink reference signal.

[0002] Looking back at the evolution of mobile communication over the past 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 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" systems.

[0003] The 6G communication system, which is expected to be realized around 2030, has a maximum transmission speed of Tera (1000 gigabit) bps (bit per second) and a wireless delay time of 100 microseconds (μsec), making it 50 times faster than the 5G communication system and reducing the wireless delay time to one-tenth.

[0004] To achieve these high data rates and ultra-low latency, 6G communication systems are being considered for implementation in terahertz bands (e.g., 95 gigahertz (GHz) to 3 terahertz (THz)). Compared to the millimeter wave (mmWave) band introduced for 5G, the terahertz band suffers from more severe path loss and atmospheric absorption, making it increasingly important to ensure signal reach, or coverage, in the long term. Key technologies to ensure coverage include RF (Radio Frequency) components, antennas, new waveforms that offer better coverage than OFDM (Orthogonal Frequency Division Multiplexing), beamforming, and multi-antenna transmission technologies such as massive 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 Surfaces (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 allows uplink (terminal transmission) and downlink (base station transmission) to utilize the same frequency resources at the same time; 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 from the technology 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 (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 mobile 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 (The Next 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 find application in diverse fields such as industry, medicine, automobiles, and home appliances.

[0007] In particular, due to the short packet arrival time of uplink (UL) XR (extended reality) traffic, when the UL transmission cycle and the UL traffic arrival cycle are similar, the conventional technique of allocating a UL grant only to a single hybrid automatic repeat and request (HARQ) process may cause additional delay time. To solve the above-mentioned problems and ensure smooth communication between the base station and the terminal, various technologies for uplink transmission and retransmission are being considered.

[0008] Based on the discussion described above, the present disclosure seeks to provide a device and method capable of performing effective signal transmission and reception in a wireless communication system.

[0009] More specifically, the present disclosure provides a device and method for reducing overhead for downlink reference signal transmission.

[0010] According to various embodiments of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system comprises the steps of: providing information related to a reception antenna port of the UE to a base station; transmitting capability information including information on a maximum number of demodulation reference signal (DMRS) groups that the UE can support to the base station; receiving, from the base station, configuration information including information on a number of DMRS groups configured for the UE; and receiving, from the base station, at least one DMRS corresponding to a number of DMRS groups based on the configuration information through different reception antenna ports of the UE, each DMRS group being associated with a different DMRS group, wherein DMRS ports having the same or different port indices assigned to each of the DMRS groups are configured, and different initialization sequences for generating a DMRS sequence can be applied to each of the DMRS groups.

[0011] According to various embodiments of the present disclosure, a method performed by a base station in a wireless communication system comprises the steps of: receiving information related to a reception antenna port of a terminal from the terminal; receiving capability information including information on a maximum number of demodulation reference signal (DMRS) groups that the terminal can support from the terminal; transmitting configuration information including information on a number of DMRS groups configured for the terminal to the terminal; and transmitting at least one DMRS corresponding to the number of DMRS groups based on the configuration information to the terminal, wherein each of the DMRS groups is associated with a different reception antenna port of the terminal, DMRS ports having the same or different port indices assigned to each of the DMRS groups are configured, and different initialization sequences for generating a DMRS sequence can be applied to each of the DMRS groups.

[0012] According to various embodiments of the present disclosure, in a wireless communication system, a user equipment (UE) is provided, the UE including: a transceiver; and a controller connected to the transceiver, wherein the controller is configured to perform the steps of: providing information related to a reception antenna port of the UE to a base station; transmitting capability information including information on a maximum number of demodulation reference signal (DMRS) groups that the UE can support to the base station; receiving, from the base station, configuration information including information on a number of DMRS groups configured for the UE; and receiving, from the base station, at least one DMRS corresponding to the number of DMRS groups based on the configuration information through different reception antenna ports of the UE, each DMRS group being associated with a different DMRS group, wherein DMRS ports having the same or different port indices assigned to each DMRS group are configured, and different initialization sequences for generating a DMRS sequence can be applied to each DMRS group.

[0013] According to various embodiments of the present disclosure, in a wireless communication system, a base station is provided, the base station including: a transceiver; and a controller connected to the transceiver, wherein the controller is configured to perform the steps of: receiving information related to a reception antenna port of a terminal from the terminal; receiving capability information including information on a maximum number of demodulation reference signal (DMRS) groups that the terminal can support from the terminal; transmitting, to the terminal, configuration information including information on a number of DMRS groups configured for the terminal; and transmitting, to the terminal, at least one DMRS corresponding to the number of DMRS groups based on the configuration information, wherein each of the DMRS groups is associated with a different reception antenna port of the terminal, and DMRS ports having the same or different port indices assigned to each of the DMRS groups are configured, and different initialization sequences for generating a DMRS sequence can be applied to each of the DMRS groups.

[0014] The present disclosure provides a device and method capable of effectively providing a service in a wireless communication system.

[0015] The present disclosure provides a device and method capable of performing effective signal transmission and reception in a wireless communication system.

[0016] The effects that can be obtained from the present disclosure are not limited to the effects mentioned in the various embodiments, and other effects that are not mentioned can be clearly understood by a person having ordinary skill in the art to which the present disclosure belongs from the description below.

[0017] FIG. 1 illustrates a wireless environment network in a wireless communication system according to various embodiments of the present disclosure.

[0018] FIG. 2 illustrates a functional configuration of a base station in a wireless communication system according to various embodiments of the present disclosure.

[0019] FIG. 3 illustrates a functional configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure.

[0020] FIG. 4 illustrates an example of a wireless resource region in a wireless communication system according to embodiments of the present disclosure.

[0021] FIG. 5 is a diagram showing an example of a DMRS pattern configuration according to various embodiments of the present disclosure.

[0022] FIG. 6 is a diagram illustrating an example of mapping a DMRS to a resource element grid according to various embodiments of the present disclosure.

[0023] FIG. 7 is a diagram illustrating an example of DMRS port allocation according to various embodiments of the present disclosure.

[0024] FIG. 8 is a diagram illustrating an example of a DMRS port pattern configuration for allocating more than 8 layers to a single terminal according to various embodiments of the present disclosure.

[0025] FIG. 9 is a diagram showing an antenna configuration of a base station of an eXtreme-MIMO system according to various embodiments of the present disclosure.

[0026] FIG. 10 is a diagram illustrating an example of a DMRS port group and a terminal receiving antenna port configuration associated with the DMRS port group according to various embodiments of the present disclosure.

[0027] FIG. 11 is a diagram illustrating an example of non-orthogonal DMRS port allocation for a single terminal according to various embodiments of the present disclosure.

[0028] FIG. 12 and FIG. 13 are diagrams showing an example of an operation in which a terminal transmits information about a channel for each receiving antenna port of the terminal to a base station according to various embodiments of the present disclosure.

[0029] FIG. 14 and FIG. 15 are diagrams showing an example of a configuration of a relationship between a terminal receiving antenna port and a non-orthogonal DMRS group operated at a base station according to various embodiments of the present disclosure.

[0030] FIG. 16 is a diagram illustrating an example of a method for indicating a DMRS scrambling ID required for generating a DMRS sequence to be used for non-orthogonal DMRS groups according to various embodiments of the present disclosure.

[0031] FIG. 17 is a diagram illustrating another example of a method for indicating a DMRS scrambling ID required for generating a DMRS sequence to be used for non-orthogonal DMRS groups according to various embodiments of the present disclosure.

[0032] FIGS. 18 to 21 are diagrams illustrating an example of a method for indicating a non-orthogonal DMRS port to a terminal using an antenna port(s) field of downlink control information (DCI) according to various embodiments of the present disclosure.

[0033] FIGS. 22 to 25 are diagrams illustrating another example of a method for indicating a non-orthogonal DMRS port to a terminal using an antenna port(s) field of downlink control information (DCI) according to various embodiments of the present disclosure.

[0034] FIG. 26 is a diagram illustrating another example of a method for indicating a non-orthogonal DMRS port to a terminal using an antenna port(s) field of downlink control information (DCI) according to various embodiments of the present disclosure.

[0035] FIG. 27 is a diagram illustrating an example of a downlink non-orthogonal DMRS reception operation of a terminal according to various embodiments of the present disclosure.

[0036] FIG. 28 is a diagram illustrating another example of a downlink non-orthogonal DMRS reception operation of a terminal according to various embodiments of the present disclosure.

[0037] FIG. 29 is a flowchart showing an example of a method of operating a terminal according to various embodiments of the present disclosure.

[0038] FIG. 30 is a flowchart illustrating an example of a method of operating a base station according to various embodiments of the present disclosure.

[0039] 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 the plural expression unless the context clearly indicates otherwise. Terms used, 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 used in this disclosure that are defined in general dictionaries may be interpreted as having the same or similar meaning as the meaning they have in the context of the relevant technology, and will 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.

[0040] The various embodiments of the present disclosure described below illustrate hardware-based approaches. However, since the various embodiments of the present disclosure include technologies utilizing both hardware and software, the various embodiments of the present disclosure do not exclude software-based approaches. Furthermore, terms referring to network entities, terms referring to device components, and the like are provided for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms with equivalent technical meanings may be used.

[0041] Additionally, although this disclosure describes various embodiments using terms defined by certain communication standards (e.g., 3rd generation partnership project (3GPP) and European Telecommunication Standards Institute (ETSI)), these are merely illustrative examples. The various embodiments of this disclosure can be easily modified and applied to other communication systems.

[0042] Additionally, in the present disclosure, expressions such as "more than" or "less than" may be used to determine whether a specific condition is satisfied or fulfilled. However, this is merely a description for expressing an example and does not exclude descriptions of more than or less than. Conditions described as "more than" may be replaced with "more than," conditions described as "less than" may be replaced with "less than," and conditions described as "more than and less than" may be replaced with "more than and less than."

[0043] The terms used in the following description, including terms referring to signals, channels, control information, network entities, and device components, are provided for convenience of explanation. Therefore, the present disclosure is not limited to the terms described below, and other terms with equivalent technical meanings may be used.

[0044] 5G systems must support services that simultaneously satisfy diverse requirements, allowing them to freely reflect the diverse needs of users and service providers. Services being considered for 5G systems include enhanced mobile broadband (eMBB), massive machine type communication (mMTC), and ultra-reliable and low-latency communication (URLLC).

[0045] eMBB aims to provide data rates that are significantly higher than those supported by existing LTE, LTE-A, or LTE-Pro. For example, in a 5G system, eMBB must be able to support a peak data rate of 20 Gbps in the downlink and a peak data rate of 10 Gbps in the uplink from the perspective of a single base station. Furthermore, 5G systems must provide both peak data rates and increased user-perceived data rates. To meet these requirements, improvements in various transmission and reception technologies, including improved multi-input, multi-output (MIMO) transmission technologies, may be required. Furthermore, while LTE systems transmit signals using a maximum transmission bandwidth of 20 MHz in the 2 GHz band, 5G systems can utilize a wider bandwidth than 20 MHz in the 3 to 6 GHz or higher frequency bands, thereby meeting the data rates required by 5G communication systems.

[0046] At the same time, mMTC is being considered to support application services such as the Internet of Things (IoT) in 5G systems. To efficiently provide the IoT, mMTC requires supporting large-scale terminal connections within a cell, improved terminal coverage, improved battery life, and reduced terminal costs. The IoT requires the ability to support a large number of terminals (e.g., 1,000,000 terminals / km2) within a cell, as it connects to various sensors and devices to provide communication functions. Furthermore, terminals supporting mMTC are likely to be located in shadow areas, such as basements, beyond cell coverage due to the nature of the service, requiring wider coverage than other services provided by 5G communication systems. Terminals supporting mMTC must be comprised of low-cost terminals, and since frequent battery replacement is difficult, they require extremely long battery lifespans, such as 10 to 16 years.

[0047] Finally, URLLC refers to cellular-based wireless communication services used for mission-critical purposes. Examples include remote control of robots or machinery, industrial automation, unmanaged aerial vehicles, remote health care, or emergency alerts. Therefore, URLLC communications must provide extremely low latency and high reliability. For example, services supporting URLLC must meet air interface latency requirements of less than 0.5 milliseconds and a packet error rate of less than 10-5. Therefore, for services supporting URLLC, 5G systems must provide shorter transmit time intervals (TTIs) than other services, while simultaneously allocating ample resources in the frequency band to ensure the reliability of the communication link.

[0048] Furthermore, data traffic for the three aforementioned services—eMBB, URLLC, and mMTC—can be multiplexed and transmitted within the 5G and / or 6G systems. To meet the varying requirements of each service, different transmission and reception techniques and parameters may be used across the services.

[0049] FIG. 1 illustrates a wireless environment network in a wireless communication system according to various embodiments of the present disclosure. FIG. 1 illustrates a base station (110), a first terminal (120), and a second terminal (130) as some of the nodes utilizing a wireless channel in the wireless communication system. While FIG. 1 illustrates only one base station, other base stations identical to or similar to the base station (110) may be included.

[0050] The base station (110) is a network infrastructure that provides wireless access to terminals (120, 130). The base station (110) has coverage defined as a certain geographical area based on the distance at which a signal can be transmitted. In addition to the base station, the base station (110) includes an 'access point (AP)', an 'eNodeB (eNB)', and a '5G node (5 th It may be referred to as 'next generation node (gNB)', 'wireless point', 'transmission / reception point (TRP)' or other terms having equivalent technical meaning.

[0051] Each of the first terminal (120) and the second terminal (130) is a device used by a user and communicates with the base station (110) via a wireless channel. In some cases, at least one of the first terminal (120) and the second terminal (130) may be operated without the involvement of the user. That is, at least one of the first terminal (120) and the second terminal (130) is a device that performs machine type communication (MTC) and may not be carried by the user. Each of the first terminal (120) and the second terminal (130) may be referred to as a 'user equipment (UE)', a 'mobile station', a 'subscriber station', a 'remote terminal', a 'wireless terminal', a 'user device', or other terms having an equivalent technical meaning thereto.

[0052] The base station (110), the first terminal (120), and the second terminal (130) can transmit and receive wireless signals in the millimeter wave (mmWave) band (e.g., 28 GHz, 30 GHz, 38 GHz, 60 GHz). At this time, in order to improve channel gain, the base station (110), the first terminal (120), and the second terminal (130) can perform beamforming. Here, the beamforming can include transmission beamforming and reception beamforming. That is, the base station (110), the first terminal (120), and the second terminal (130) can provide directionality to a transmission signal or a reception signal. To this end, the base station (110) and the terminals (120, 130) can select serving beams through a beam search or beam management procedure. After serving beams are selected, subsequent communications can be performed through resources that are in a quasi-co-located (QCL) relationship with the resource that transmitted the serving beams.

[0053] If large-scale characteristics of a channel carrying a symbol on a first antenna port can be inferred from a channel carrying a symbol on a second antenna port, the first antenna port and the second antenna port can be evaluated to have a QCL relationship. For example, the large-scale characteristics may include at least one of delay spread, Doppler spread, Doppler shift, average gain, average delay, and a spatial receiver parameter.

[0054] FIG. 2 illustrates the functional configuration of a base station in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in FIG. 2 may be understood as the configuration of a base station (110). Terms such as "... unit" and "... unit" used hereinafter refer to a unit that processes at least one function or operation, which may be implemented using hardware, software, or a combination of hardware and software.

[0055] Referring to FIG. 2, the base station includes a wireless communication unit (210), a backhaul communication unit (220), a storage unit (230), and a control unit (240).

[0056] The wireless communication unit (210) performs functions for transmitting and receiving signals via a wireless channel. For example, the wireless communication unit (210) performs a conversion function between baseband signals and bit streams according to the physical layer specifications of the system. For example, when transmitting data, the wireless communication unit (210) encodes and modulates the transmitted bit stream to generate complex symbols. Additionally, when receiving data, the wireless communication unit (210) restores the received bit stream by demodulating and decoding the baseband signal.

[0057] In addition, the wireless communication unit (210) 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. To this end, the wireless communication unit (210) 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 wireless communication unit (210) may include a plurality of transmission and reception paths. Furthermore, the wireless communication unit (210) may include at least one antenna array composed of a plurality of antenna elements.

[0058] In terms of hardware, the wireless communication unit (210) may be composed of a digital unit and an analog unit, and the analog unit may be composed of a plurality of sub-units depending on operating power, operating frequency, etc. The digital unit may be implemented with at least one processor (e.g., a digital signal processor (DSP)).

[0059] The wireless communication unit (210) transmits and receives signals as described above. Accordingly, all or part of the wireless communication unit (210) may be referred to as a "transmitter," a "receiver," or a "transceiver." Furthermore, in the following description, transmission and reception performed via a wireless channel are used to mean that the wireless communication unit (210) performs the processing described above.

[0060] The backhaul communication unit (220) provides an interface for communicating with other nodes within the network. That is, the backhaul communication unit (220) converts a bit string transmitted from a base station to another node, such as another access node, another base station, an upper node, a core network, etc., into a physical signal, and converts a physical signal received from another node into a bit string.

[0061] The storage unit (230) stores data such as basic programs, application programs, and setting information for the operation of the base station. The storage unit (230) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. In addition, the storage unit (230) provides stored data upon request from the control unit (240).

[0062] The control unit (240) (or controller) controls the overall operations of the base station. For example, the control unit (240) transmits and receives signals through the wireless communication unit (210) or the backhaul communication unit (220). In addition, the control unit (240) records and reads data in the storage unit (230). In addition, the control unit (240) can perform the functions of the protocol stack required by the communication standard. According to another implementation example, the protocol stack can be included in the wireless communication unit (210). To this end, the control unit (240) can include at least one processor.

[0063] According to various embodiments, the control unit (240) can control the base station to perform operations according to various embodiments described below.

[0064] FIG. 3 illustrates the functional configuration of a terminal in a wireless communication system according to various embodiments of the present disclosure. The configuration illustrated in FIG. 3 may be understood as the configuration of terminals (120, 130). Terms such as "...unit" and "...unit" used hereinafter refer to a unit that processes at least one function or operation, which may be implemented using hardware, software, or a combination of hardware and software.

[0065] Referring to FIG. 3, the terminal includes a communication unit (310), a storage unit (320), and a control unit (330).

[0066] The communication unit (310) performs functions for transmitting and receiving signals via a wireless channel. For example, the communication unit (310) 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 (310) generates complex symbols by encoding and modulating a transmission bit stream. In addition, when receiving data, the communication unit (310) restores a reception bit stream by demodulating and decoding the baseband signal. In addition, the communication unit (310) 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 (310) may include a transmission filter, a reception filter, an amplifier, a mixer, an oscillator, a DAC, an ADC, etc.

[0067] In addition, the communication unit (310) may include a plurality of transmission and reception paths. Furthermore, the communication unit (310) may include at least one antenna array composed of a plurality of antenna elements. In terms of hardware, the communication unit (310) 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 (310) may include a plurality of RF chains. Furthermore, the communication unit (310) may perform beamforming.

[0068] The communication unit (310) transmits and receives signals as described above. Accordingly, all or part of the communication unit (310) 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 (310) as described above.

[0069] The storage unit (320) stores data such as basic programs, application programs, and setting information for the operation of the terminal. The storage unit (320) may be composed of volatile memory, non-volatile memory, or a combination of volatile and non-volatile memory. In addition, the storage unit (320) provides stored data upon request from the control unit (330).

[0070] The control unit (330) (or controller) controls the overall operations of the terminal. For example, the control unit (330) transmits and receives signals through the communication unit (310). In addition, the control unit (330) records and reads data in the storage unit (320). In addition, the control unit (330) can perform the functions of the protocol stack required by the communication standard. To this end, the control unit (330) may include at least one processor or microprocessor, or may be a part of a processor. In addition, a part of the communication unit (310) and the control unit (330) may be referred to as a CP (communication processor).

[0071] According to various embodiments, the control unit (330) can control the terminal to perform operations according to various embodiments described below.

[0072] FIG. 4 illustrates an example of a wireless resource region in a wireless communication system according to embodiments of the present disclosure. In various embodiments of the present disclosure, the wireless resource region may include a structure in the time-frequency domain. In one embodiment, the wireless communication system may include an NR communication system.

[0073] Referring to FIG. 4, 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 (404) is 10 ms. The radio frame (404) may be a time domain section composed of 10 subframes. The length of a subframe (403) is 1 ms. The unit of configuration in the time domain may be an orthogonal frequency division multiplexing (OFDM) and / or a DFT-s-OFDM (DFT (discrete Fourier transform)-spread-OFDM) symbol, and Nsymb OFDM and / or DFT-s-OFDM symbols (401) may be gathered to form one slot (402). According to various embodiments of the present disclosure, 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 may be composed of a total of NscBW subcarriers (405). In addition, in the present disclosure, for the convenience of explanation, an embodiment regarding downlink signal transmission and reception is described, but this can also be applied to an embodiment regarding uplink signal transmission and reception.

[0074] According to one embodiment, the number of slots (402) constituting one subframe (403) and the length of the slots (402) may vary depending on the subcarrier spacing. This subcarrier spacing may be referred to as a numerology (μ). For example, the subcarrier spacing, the number of slots included in a subframe, the length of the slots, and the length of the subframe may be configured variably. For example, in an NR communication system, when the subcarrier spacing (SCS) is 15 kHz, one slot (402) constitutes one subframe (403), and the lengths of the slot (402) and the subframe (403) may each be 1 ms. In addition, for example, when the subcarrier spacing is 30 kHz, two slots may constitute one subframe (403). In this case, the length of the slot is 0.5 ms and the length of the subframe is 1 ms.

[0075] In one embodiment, the subcarrier spacing, the number of slots included in a subframe, the length of the slot, and the length of the subframe may be variably applied depending on the communication system. For example, in the case of an LTE system, the subcarrier spacing may be 15 kHz, two slots may 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. As another example, in the case of an NR system, the subcarrier spacing (μ) may be one of 15 kHz, 30 kHz, 60 kHz, 120 kHz, 240 kHz, 480 kHz, and 960 kHz, and the number of slots included in one subframe depending on the subcarrier spacing (μ) may be 1, 2, 4, 8, 16, 32, and 64.

[0076] In the time-frequency domain, a basic unit of a resource may be a resource element (RE) (406), and the RE (406) 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)) (407) may be defined by N S CRB consecutive subcarriers in the frequency domain. The number of subcarriers may be N S CRB = 12. The frequency domain may include common resource blocks (CRBs). A physical resource block (PRB) may be defined in a bandwidth part (BWP) in the frequency domain. The CRB and PRB numbers may be determined differently depending on the subcarrier spacing. In an LTE system, an RB may be defined by N symb consecutive OFDM symbols in the time domain and N S CRB consecutive subcarriers in the frequency domain.

[0077] In NR and / or LTE systems, scheduling information for downlink data or uplink data may be transmitted from a base station (110) to a terminal (120) via downlink control information (DCI). According to various embodiments of the present disclosure, 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. Also, for example, NR DCI format 0_0 or NR DCI format 0_1 ​​may include scheduling for uplink data.

[0078] As described above, FIG. 4 illustrates an example of a downlink and uplink slot structure in a wireless communication system. In particular, FIG. 4 illustrates the structure of a resource grid of a 3GPP NR system. Referring to FIG. 4, 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 slot may generally vary depending on the length of a cyclic prefix (CP). In FIG. 4, for convenience of explanation, a case in which a slot is composed of 14 OFDM symbols is illustrated, but the signal referred to in the present disclosure does not specify the symbol configuration. 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).

[0079] According to various embodiments of the present disclosure, operations for controlling uplink retransmission for efficient signal transmission are described based on an LTE communication system or an NR communication system. However, 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, it goes without saying that the contents of the present disclosure can be applied to unlicensed bands as well as licensed bands, as needed.

[0080] Hereinafter, in the present disclosure, higher layer signaling or higher signal may be a signal transmission method in which a base station (110) transmits a downlink data channel of a physical layer to a terminal (120), or a terminal (120) transmits a signal to a base station (110) using an uplink data channel of a physical layer. According to one 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 medium access control (MAC) control element (MAC CE). In addition, according to one embodiment, the higher layer signaling or higher signal may include system information commonly transmitted to a plurality of terminals (120), for example, a system information block (SIB).

[0081] 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 addition, the SSB may include information about a beam that the base station uses to transmit a signal, and the SSB index or SSB described below may mean at least one beam. In the initial access phase when a terminal first accesses the system, the terminal may obtain downlink time and frequency domain synchronization and a cell ID from a synchronization signal through a cell search procedure. The synchronization signal may include a PSS and an SSS. The terminal may receive a PBCH including a master information block (MIB) from the base station to obtain 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 terminal can decode the physical downlink control channel (PDCCH) and physical downlink shared channel (PDSCH) to obtain a system information block (SIB). Afterwards, the terminal can exchange identities with the base station through a random access phase and undergo registration, authentication, and other steps to initially access the network.

[0082] As described above, one slot may include 14 symbols, and according to various embodiments of the present disclosure, the uplink-downlink configuration of symbols and / or slots in a 5G communication system may be set in three stages.

[0083] In the first method, the uplink-downlink of a symbol and / or slot can be configured semi-statically through cell-specific configuration information via system information at the symbol level. More specifically, the cell-specific uplink-downlink configuration information via system information may include uplink-downlink pattern information and reference subcarrier information. The uplink-downlink pattern information may indicate a pattern periodicity, the number of consecutive downlink slots from the start of each pattern, the number of symbols in the next slot, the number of consecutive uplink slots from the end of the pattern, and the number of symbols in the next slot. Slots and symbols that are not indicated as uplink or downlink may be considered flexible slots / symbols.

[0084] In a second way, through user-specific configuration information via dedicated upper layer signaling, a flexible slot or a slot containing flexible symbols can be indicated by the number of consecutive downlink symbols from the start symbol of the slot and the number of consecutive uplink symbols from the end of the slot, or by the entire downlink or the entire uplink of the slot, respectively.

[0085] In a third method, in order to dynamically change the downlink signal transmission and uplink signal transmission sections, symbols indicated as flexible symbols in each slot (e.g., symbols not indicated as downlink or uplink) can be indicated as downlink symbols, uplink symbols, or flexible symbols, through a slot format indicator (SFI) included in a downlink control channel. The slot format indicator can select one index from a table in which an uplink-downlink configuration of 14 symbols in one slot is preset.

[0086] Below, before explaining a method for supporting a non-orthogonal demodulation reference signal for a terminal performing SU-MIMO operation, the concepts of an orthogonal demodulation reference signal and a non-orthogonal demodulation reference signal are first explained.

[0087] Orthogonal Demodulation Reference Signal in 5G NR

[0088] In 5G NR, for the receiver to decode signals transmitted through various physical layer channels such as a physical downlink shared channel (PDSCH), a physical uplink shared channel (PUSCH), a physical downlink control channel (PDCCH), and a physical uplink control channel (PUCCH), an additional reference signal may be transmitted to a resource element (RE). At this time, a signal transmitted together with a signal transmitted through a physical layer channel is called a Demodulation Reference Signal (DMRS). At this time, in the case of a DMRS transmitted together with a data channel, such as a PUSCH and / or PDSCH, at least one DMRS pattern is inserted for every PDSCH or PUSCH transmission, which may result in signaling overhead.

[0089] In 5G NR, up to 12 orthogonal DMRS ports can be supported. Orthogonal DMRS can be supported by configuring DMRS patterns defined in the form of frequency domain-orthogonal cover code (FD-OCC), time domain-orthogonal cover code (TD-OCC), and Comb, and ensuring orthogonality between the configured DMRS patterns. The terminal can calculate channel and interference components for each layer using orthogonal DMRS in the data channel, and can restore the data channel using the calculated channel and interference components for each layer.

[0090] FIG. 5 is a diagram illustrating an example of a DMRS pattern configuration according to various embodiments of the present disclosure. More specifically, FIG. 5 relates to a DMRS pattern for each port of a DMRS transmitted using two OFDM symbols supported during PDSCH transmission. The DMRS patterns illustrated in FIG. 5 are defined and configured in the form of a frequency domain-orthogonal cover code (FD-OCC), a time domain-orthogonal cover code (TD-OCC), and a comb, and each of 510 to 565 in FIG. 5 can sequentially correspond to 12 DMRS port patterns 1000 to 1011, respectively.

[0091] FIG. 6 is a diagram illustrating an example of mapping a DMRS to a resource element grid according to various embodiments of the present disclosure.

[0092] Referring to Fig. 6, a DMRS sequence called r(n) is applied to each DMRS pattern (610) (615), and the DMRS generated accordingly can be mapped to a resource element grid (620). At this time, the sequence r(n) is a DMRS scrambling ID ( ) can be generated by modulating c(n) with QPSK. When up to 12 orthogonal DMRS ports are supported, the same sequence r(n) must be used among DMRS ports included in the same CDM group (e.g., p=1000, 1001, 1006, 1007) so that the terminal can estimate the channel and interference at different DMRS ports.

[0093] Non-orthogonal Demodulation Reference Signal in 5G NR

[0094] As explained above, when orthogonal DMRS port allocation is performed, different DMRS ports can be indicated to terminals. Unlike orthogonal DMRS port allocation, when supporting MU-MIMO in 5G NR, the base station can allocate the same DMRS port to other terminals as the DMRS port assigned to a specific terminal. In particular, when the base station allocates the same DMRS port between different layers, this can be called non-orthogonal DMRS. When non-orthogonal DMRS is operated, the base station can minimize interference between non-orthogonal DMRS ports by using different r(n) sequences or DMRS scrambling IDs ( ) can be used. Non-orthogonal DMRS has less resource overhead than orthogonal DMRS, and non-orthogonal DMRS can be mainly used when the estimated channel between the base station and the terminal is accurate and the precoder used by the base station can effectively remove interference between layers.

[0095] FIG. 7 is a diagram illustrating an example of DMRS port allocation according to various embodiments of the present disclosure. More specifically, FIG. 7 illustrates DMRS port allocation for each of a plurality of terminals performing MU-MIMO operation. First, referring to an example of orthogonal DMRS port allocation (710), three terminals (701, 703, and 705) perform MU-MIMO operation, and different DMRS ports are allocated to each terminal. That is, DMRS ports 1001 and 1002 may be allocated for PDSCH reception for a first terminal (701), DMRS ports 1003 and 1004 may be allocated for PDSCH reception for a second terminal (703), and DMRS ports 1005 and 1006 may be allocated for PDSCH reception for a third terminal (705). Meanwhile, referring to an example of non-orthogonal DMRS port allocation (715), four terminals (701, 703, 705, 707) perform MU-MIMO operation, and at this time, the same DMRS port may be allocated to some of the terminals (701, 707). That is, DMRS ports 1001 and 1002 may be allocated to the first terminal (701) for PDSCH reception, DMRS ports 1003 and 1004 may be allocated to the second terminal (703) for PDSCH reception, DMRS ports 1005 and 1006 may be allocated to the third terminal (705) for PDSCH reception, and DMRS ports 101 and 1002, which are the same as the DMRS ports allocated to the first terminal (701), may be allocated to the fourth terminal (707). At this time, for the first terminal (701) and the fourth terminal (707), the DMRS port number is the same, but different DMRS sequences r(n) are used, or different DMRS scrambling IDs ( ) are allocated, the first terminal (701) and the fourth terminal (707) can remove residual interference components between layers that the precoder of the base station could not completely remove.

[0096] Currently, 5G NR allows for the same DMRS port to be assigned to multiple terminals, but there is no way to assign the same DMRS port to a single terminal. However, this disclosure considers a scenario where more than eight layers are assigned to a single terminal. Assigning only orthogonal DMRS ports to a single terminal can result in excessive overhead.

[0097] FIG. 8 is a diagram illustrating an example of a DMRS port pattern configuration for allocating more than 8 layers to a single terminal according to various embodiments of the present disclosure. More specifically, FIG. 8 relates to a method of increasing the OCC length applied when configuring a DMRS port pattern in the time domain to allocate more than 8 layers to a single terminal through SU-MIMO. In the case of FIG. 8, the OCC length applied as 2 in the example of FIG. 5 is increased to 4, and by applying the OCC length as 4, an orthogonal DMRS port pattern of up to 24 layers can be configured (810). That is, 1000 to 1023 orthogonal DMRS port patterns can be configured.

[0098] The DMRS port pattern of Fig. 8 applies the same DMRS density in frequency as the DMRS port pattern of Fig. 5. Referring to Fig. 8, when a method of increasing the value of the OCC length applied when configuring the DMRS port pattern is used, there is a problem that the overhead occupied by resources for orthogonal DMRS transmission on the resource grid may significantly increase as the number of layers allocated to a single terminal increases (815). That is, in the case of Fig. 5, only two OFDM symbols are used on the resource grid for orthogonal DMRS transmission, whereas in the case of Fig. 8, four OFDM symbols are used on the resource grid for orthogonal DMRS transmission, so the overhead occupied by resources for orthogonal DMRS transmission on the resource grid may significantly increase.

[0099] Therefore, in situations where more than 8 layers are allocated to a single terminal, a method for allocating non-orthogonal DMRS ports may be required to reduce overhead. In other words, a method for allocating the same DMRS port to a single terminal may be required.

[0100] FIG. 9 is a diagram illustrating an antenna configuration of a base station of an eXtreme-MIMO system according to various embodiments of the present disclosure. In an eXtreme-MIMO system, the number of antennas and digital ports of a base station may significantly increase. Referring to FIG. 9, while 192 TRXs are used in an NR base station (910), 3,072 TRXs may be used in an eXtreme-MIMO system base station (915). In an eXtreme-MIMO system, more accurate channel estimation can be achieved by utilizing a large number of antennas and digital ports on the base station side, and interference between layers can be dramatically reduced compared to 5G NR by utilizing a more accurate precoder. Through the advantages of accurate channel estimation and dramatically reduced interference between layers in an eXtreme-MIMO system, interference between layers can be effectively reduced even when non-orthogonal DMRSs are assigned to a single terminal. Additionally, when assigning non-orthogonal DMRS to a single terminal, the problem of increased DMRS overhead due to increased layers, as previously described in the example of Figure 8, can be resolved. Below, a method for assigning non-orthogonal DMRS to a single terminal is described.

[0101] More specifically, the method for allocating a non-orthogonal DMRS to a single terminal of the present disclosure includes a method of indicating a non-orthogonal DMRS group (group) that is associated with different receive antenna ports of the terminal and each uses a different r(n) sequence, when the terminal transmits information about the receive antenna ports of the terminal to the base station through SRS / CSI-RS, etc. In this case, the non-orthogonal DMRS group (group) that each uses a different r(n) sequence may mean a DMRS group configured to include the same DMRS port. In addition, the method for allocating a non-orthogonal DMRS to a single terminal of the present disclosure includes a DMRS scrabbling ID () used to generate a DMRS sequence r(n) used in each of the DMRS (non-orthogonal) groups of the terminal. ) and a method for indicating the same. In addition, the method for allocating non-orthogonal DMRS to a single terminal of the present disclosure includes a method for indicating a non-orthogonal DMRS port to the terminal through an antenna port(s) field of downlink control information (DCI) for DMRS transmission through non-orthogonal DMRS port allocation on a data channel (PDSCH / PUSCH). Finally, the method for allocating non-orthogonal DMRS to a single terminal of the present disclosure includes a method for operating the terminal when the terminal operates as a receiver of a data channel (PDSCH). It should be understood that at least one of the methods included in the present disclosure may be combined with each other and performed as a single overall operation.

[0102] FIG. 10 is a diagram illustrating an example of a DMRS port group and a configuration of terminal reception antenna ports associated with a DMRS port group according to various embodiments of the present disclosure. Referring to FIG. 10, a terminal includes eight reception antenna ports, and the terminal transmits information about the reception antenna ports of the terminal to a base station via SRS / CSI-RS, etc., and the base station can identify the reception antenna ports of the terminal through this. At this time, DMRS port group 1 (1001) may be associated with four of the eight reception antenna ports of the terminal and the reception antenna ports, and DMRS port group 2 (1002) may be associated with the remaining four reception antenna ports, excluding the four reception antenna ports associated with DMRS port group 1 (1001), among the eight terminal reception antenna ports. At this time, DMRS port group 1 (1001) and DMRS port group 2 (1002) may be configured to be non-orthogonal to each other by including DMRS ports of ports 1000 to 1003, which are the same DMRS ports. Here, different sequences may be used for the DMRS sequence r(n) for creating a DMRS port included in DMRS port group 1 (1001) and the DMRS sequence r(n) for creating a DMRS port included in DMRS port group 2 (1002).

[0103] FIG. 11 is a diagram illustrating examples of non-orthogonal DMRS port allocation for a single terminal according to various embodiments of the present disclosure. Referring to FIG. 11 , it can be seen that two non-orthogonal, different DMRS groups (1110, 1115) containing the same DMRS port can be allocated to a single terminal. In this case, each of the DMRS groups (1110, 1115) can be associated with a different receive antenna port of the terminal, and a different DMRS sequence r(n) can be used for each of the DMRS groups (1110, 1115).

[0104] Hereinafter, a method for indicating non-orthogonal DMRS groups, each associated with a different receive antenna port of a terminal, when the terminal transmits information about the terminal's receive antenna ports to a base station via SRS / CSI-RS, etc. is described. In this method, different r(n) sequences and / or scrambling ID sequences (cinit) may be used for each non-orthogonal DMRS group to minimize interference.

[0105] When a terminal transmits information about terminal capability (UE capability) to a base station, the terminal may report information about the maximum number of non-orthogonal DMRS groups that the terminal can operate for data channel (PUSCH / PDSCH) transmission / reception, including the information in the terminal capability information. At this time, the information about the terminal capability may be transmitted via RRC (radio resource control) signaling. For example, in the case of PDSCH reception by the terminal, the terminal may report information about the maximum number of downlink non-orthogonal DMRS groups that the terminal can operate for PDSCH reception, including the information in the terminal capability information.

[0106] Thereafter, the base station can transmit information about the number of non-orthogonal DMRS groups that the base station can operate to the terminal that transmitted the information about the terminal's capabilities. Information about the number of non-orthogonal DMRS groups that the base station can operate to the terminal can be transmitted to the terminal as configuration information through RRC (radio resource control) signaling. In this case, the number of non-orthogonal DMRS groups that the base station can instruct the terminal can be set to a number equal to or less than the maximum number of non-orthogonal DMRS groups that the terminal can operate, as reported by the terminal.

[0107] For example, in the case of PDSCH reception by a terminal, the base station can transmit information on the number of downlink non-orthogonal DMRS groups that the base station can operate to the terminal that transmitted information on the terminal capability. At this time, the number of downlink non-orthogonal DMRS groups that the base station can instruct the terminal can be set to a number equal to or smaller than the number of downlink non-orthogonal DMRS groups that the terminal can operate at most as reported by the terminal. More specifically, when the number of downlink non-orthogonal DMRS groups that the terminal can operate at most as reported by the terminal to the base station is 4, the number of downlink non-orthogonal DMRS groups that the base station can instruct the terminal can be set to a number less than or equal to 4.

[0108] FIG. 12 and FIG. 13 illustrate examples of operations in which a terminal transmits information about its receiving antenna port to a base station according to various embodiments of the present disclosure. Typically, as illustrated in FIG. 12 and FIG. 13 , a terminal may indirectly inform the base station of information about channels for each receiving antenna port using SRS / CSI-RS, etc.

[0109] First, referring to FIG. 12, which illustrates an example in which a terminal transmits information about a receiving antenna port of the terminal to a base station through an SRS, the terminal (1210) can inform the base station (1220) of a channel for each antenna port of the terminal through a TAS (Transmit Antenna Switching) operation. The TAS (Transmit Antenna Switching) operation may mean an operation in which the terminal transmits an SRS to the base station through each transmitting antenna port while changing the transmitting antenna port. At this time, the base station can recognize the antenna ports in the order of the channels for each antenna port that the terminal informs the base station. That is, the base station can recognize the channels related to each antenna port sequentially, such as AP0 => AP1 => AP2 => AP3 (1230), and thereby obtain information about the receiving antenna port of the terminal. Here, for the operation of the base station acquiring information about the receiving antenna port through the channel related to the transmitting antenna port of the terminal, channel reciprocity, which can assume that the characteristics of the uplink channel and the downlink channel are the same, can be assumed.

[0110] Next, referring to FIG. 13, which illustrates an example in which a terminal transmits information about a receiving antenna port of the terminal to a base station through CSI feedback based on CSI-RS, the terminal (1310) transmits CSI feedback based on CSI-RS received from the base station (1320) to the base station (1320), where the CSI feedback may be CSI-related feedback (e.g., PMI) based on a channel matrix generated by the terminal in the order of AP0 => AP1 => AP2 => AP3, which are antenna ports of the terminal (1330). The base station (1320), which receives the CSI feedback from the terminal (1310), may restore the channel using an eigenvector, and at this time, the restored channel may have a form in which the antenna port order (AP0 => AP1 => AP2 => AP3) applied when generating the channel matrix of the terminal (1310) is maintained. That is, the base station (1320) can obtain information about the order and channel of the antenna ports of the terminals by restoring the channels for each receiving antenna of the terminal (1310) related to the receiving antenna ports of each terminal in the order of AP0 => AP1 => AP2 => AP3.

[0111] Assuming that the base station has identified the channel for each receiving antenna port of the terminal through the operations described in FIGS. 12 and 13, the following describes methods for the base station to indicate to the terminal a non-orthogonal DMRS group associated with the receiving antenna port of the terminal. The non-orthogonal DMRS port sets operated by the base station may refer to a non-orthogonal DMRS group.

[0112] First, if the terminal notifies the base station of N receiving antenna ports and K non-orthogonal DMRS groups are set to be operated, the base station and the terminal will operate in the order of the receiving antenna ports. It is assumed / configured that ports are each associated with K different non-orthogonal DMRS groups, and at this time, the last non-orthogonal DMRS group can be assumed / configured to be associated with the remaining antenna ports except for the receiving antenna ports of the terminal that are associated with K-1 non-orthogonal DMRS groups. That is, the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group among the DMRS groups is the same, and the last DMRS group can include the number of receiving antenna ports remaining excluding the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group. More specifically, when the number of receiving antenna ports of the terminal is N (N is a natural number) and the number of DMRS groups is K (K is a natural number), the receiving antenna ports of the terminal can be indexed with numbers from 1 to N, and the DMRS groups can be indexed with numbers from 1 to K. At this time, *(K-1) number of receiving antenna ports Each DMRS group is assigned an index from 1 to K-1 in units of N, and is associated with each other according to the ascending order of the index assigned to the receiving antenna port and the ascending order of the index assigned to the DMRS group, (N- *(K-1)) receiving antenna ports can be associated with the DMRS group to which the index K is assigned. For example, if the number of receiving antenna ports of the terminal is 7 and the number of configured non-orthogonal DMRS groups is 2, port indices from 1 to 7 can be assigned, respectively, and two non-orthogonal DMRS groups can be assigned group indices of 1 and 2, respectively. In this case, receiving antenna ports assigned with port indices 1 to 4 can be associated with a non-orthogonal DMRS group assigned with group index 1, and receiving antenna ports assigned with port indices 5 to 7 can be associated with a non-orthogonal DMRS group assigned with group index 2.

[0113] Next, the base station can explicitly indicate the non-orthogonal DMRS group associated with each of the receive antenna ports of the terminal, and the base station can individually indicate the receive antenna ports of the terminal associated with the non-orthogonal DMRS groups for all operable non-orthogonal DMRS groups to the terminal. At this time, RRC signaling can be used to indicate the receive antenna ports of the terminal associated with the non-orthogonal DMRS groups to the terminal. For example, if the base station can operate two sets of non-orthogonal DMRS groups, the RRC parameter DMRS-DownlinkConfig includes configuration information (e.g., dmrsGroup1, etc.) for indicating the terminal receive antenna port associated with DMRS group 1 and configuration information (e.g., dmrsGroup2, etc.) for indicating the terminal receive antenna port associated with DMRS group 2, and the base station can indicate the non-orthogonal DMRS group associated with the terminal receive antenna port to the terminal through the configuration information.

[0114] The base station can configure and indicate different non-orthogonal DMRS groups associated with each receive antenna port of the terminal in different forms depending on the situations in which different numbers of non-orthogonal DMRS groups are operated. More specifically, when the number of receive antenna ports of the terminal is 8 and the number of configured non-orthogonal DMRS groups is 2, configuration information for receive antenna ports of the terminal associated with the first non-orthogonal DMRS group (e.g., antenna ports 1 to 4) and configuration information for receive antenna ports of the terminal associated with the second non-orthogonal DMRS group (e.g., antenna ports 5 to 8) can be configured. In addition, when the number of receiving antenna ports of the terminal is 8 and the number of configured non-orthogonal DMRS groups is 4, configuration information for receiving antenna ports (e.g., antenna ports 1 to 2) of the terminal associated with the first non-orthogonal DMRS group, configuration information for receiving antenna ports (e.g., antenna ports 3 to 4) of the terminal associated with the second non-orthogonal DMRS group, configuration information for receiving antenna ports (e.g., antenna ports 5 to 6) of the terminal associated with the third non-orthogonal DMRS group, and configuration information for receiving antenna ports (e.g., antenna ports 7 to 8) of the terminal associated with the fourth non-orthogonal DMRS group may be configured.

[0115] Additionally, in the present method, since the base station can explicitly configure the receiving antenna ports of the terminal associated with the non-orthogonal DMRS group, the configuration of the receiving antenna ports of the terminal associated with a specific non-orthogonal DMRS group can be configured in various ways. For example, in the case where the number of receiving antenna ports of the terminal described above is 8 and the number of configured non-orthogonal DMRS groups is 2, unlike the case where the antenna ports are sequentially configured to be associated with each non-orthogonal DMRS group, antenna ports 1, 3, 5, and 7 can be configured to be associated with non-orthogonal DMRS group 1, and antenna ports 2, 4, 6, and 8 can be configured to be associated with non-orthogonal DMRS group 2. More generally, if the number of receiving antenna ports of the terminal is 8 and the number of configured non-orthogonal DMRS groups is 2, the number of cases in which one non-orthogonal DMRS group can be associated with 4 receiving antenna ports out of the 8 receiving antenna ports is 8C4 (8*7*6*5 / 4*3*2*1). Therefore, according to the present embodiment, if the number of receiving antenna ports of the terminal is 8 and the number of configured non-orthogonal DMRS groups is 2, the number of possible association configurations between non-orthogonal DMRS port groups and the receiving antenna ports of the terminal can be 8C4. Alternatively, it may also be possible to apply the present method by setting the number of receiving antenna ports of the terminal associated with each non-orthogonal DMRS port group to a different number.

[0116] For example, if the number of receiving antenna ports of a terminal is 8 and the number of configured non-orthogonal DMRS groups is 2, the receiving antenna ports of 5 terminals can be configured to be associated with the first non-orthogonal DMRS group, and the receiving antenna ports of 3 terminals can be configured to be associated with the second non-orthogonal DMRS group. At this time, the number of cases in which 3 receiving antenna ports among the 8 receiving antenna ports can be associated with the first non-orthogonal DMRS group is 8C3 (8*7*6 / 3*2*1), and since the 3 receiving antenna ports associated with the first DMRS group are determined, the remaining 5 receiving antenna ports are associated with the remaining DMRS groups, and therefore, according to one embodiment, the number of possible configurations of associations between non-orthogonal DMRS port groups and receiving antenna ports of a terminal can be 8C3.

[0117] Finally, the base station may indicate non-orthogonal DMRS groups associated with the antenna ports of the terminal, but the indication may be performed only for some specific non-orthogonal DMRS groups operated by the base station. At this time, for the remaining K non-orthogonal DMRS groups and the remaining N receive antenna ports that are not separately indicated, in order It can be assumed that each port is associated with a different DMRS group. In other words, this method may be a hybrid of the two methods described above.

[0118] FIGS. 14 and 15 are diagrams illustrating an example of a configuration of an association relationship between a terminal receiving antenna port and a non-orthogonal DMRS group operated by a base station according to various embodiments of the present disclosure. More specifically, FIGS. 14 and 15 are diagrams illustrating a method in which an association relationship between a terminal and a base station is implicitly assumed / established based on a receiving antenna port index and a non-orthogonal DMRS group index, without the base station explicitly configuring the association relationship between the terminal's receiving antenna port and the non-orthogonal DMRS group.

[0119] First, referring to FIG. 14, it can be seen that the terminal notifies the base station of 16 receiving antenna ports in the form of two sets of 8 by 1 uniform linear array antennas through SRS or CSI-RS feedback, and the base station operates two non-orthogonal DMRS groups. At this time, receiving antenna ports 1 to 8 of the terminal can be set / assumed between the terminal and the base station to be associated with non-orthogonal DMRS group 1, and receiving antenna ports 9 to 16 of the terminal can be set / assumed between the terminal and the base station to be associated with non-orthogonal DMRS group 2.

[0120] Next, referring to FIG. 15, it can be seen that this is a case where a terminal having a uniform cross-polarized antenna configuration of (M, N, P) = (4, 1, 2) notifies a base station of eight receive antenna ports through SRS or CSI-RS feedback, and the base station operates two non-orthogonal DMRS groups. At this time, receive antenna ports 1 to 4 of the terminal may be set / assumed between the terminal and the base station to be associated with non-orthogonal DMRS group 1, and receive antenna ports 5 to 8 of the terminal may be set / assumed between the terminal and the base station to be associated with non-orthogonal DMRS group 2.

[0121] Below, the DMRS scrambling ID to be used for each non-orthogonal DMRS group set to the terminal ( ) describes a method for defining and indicating.

[0122] DMRS scrambling ID required to generate DMRS sequences to be used for non-orthogonal DMRS groups ( ) as a first method to indicate (or assume) the previously used (CDM group , DMRS (defined by star) There is a method of using a DMRS (non-orthogonal) group. This will be described in more detail with reference to FIG. 16. FIG. 16 is a diagram showing an example of a method for indicating a DMRS scrambling ID required for generating a DMRS sequence to be used for non-orthogonal DMRS groups according to various embodiments of the present disclosure. In the method according to FIG. 16, the DMRS scrambling ID ( ) can be defined as the mathematical formula below.

[0123]

[0124] In Fig. 16, when operating two DMRS groups, the first non-orthogonal DMRS group is used for generating DMRS sequences. The value is used (1610), for the second non-orthogonal DMRS group, for the DMRS sequence generation of the first non-orthogonal DMRS group. The value can be used in a modified form. More specifically, when only one DMRS group is set, the value indicated by the DCI field The value can have either 0 or 1, and is not indicated by the DCI field. Others generated based on values The value may not be used. In contrast, if two non-orthogonal DMRS groups are set, the same value is used for the first non-orthogonal DMRS group as in the case where only one DMRS group is used. , and for the second non-orthogonal DMRS group, a modified If a value is used, it is used for the first non-orthogonal DMRS group. having a different value than the value One more set of non-orthogonal DMRS groups can be used, since it can be used for the second non-orthogonal DMRS group.

[0125] DMRS scrambling ID required to generate DMRS sequences to be used for non-orthogonal DMRS groups ( ) to indicate (or assume) a new DMRS scrambling ID ( ) to be used for non-orthogonal DMRS groups. ) is defined. This will be described in more detail with reference to FIG. 17. FIG. 17 is a diagram illustrating another example of a method for indicating a DMRS scrambling ID required for generating a DMRS sequence to be used for non-orthogonal DMRS groups according to various embodiments of the present disclosure. In the method according to FIG. 17, the DMRS scrambling ID ( ) can be defined as the mathematical formula below.

[0126]

[0127] Unlike the method according to Fig. 16, the DMRS scrambling ID of the method according to Fig. 17 ( ) The mathematical formula for generation includes parameters may include more. silver It may be a parameter indicating the th non-orthogonal DMRS group. For example, if there are a total of 4 non-orthogonal DMRS groups operated by the base station, The values ​​can be 0, 1, 2, 3 depending on the corresponding non-orthogonal DMRS group. Fig. 17 is for the case where two non-orthogonal DMRS groups are operated, CDM group, , DMRS scrambling ID used for each of the first non-orthogonal DMRS group (1710) and the second non-orthogonal DMRS group (1720) in the value The values ​​can be set differently.

[0128] In addition, in common with the methods described above, the terminal reports to the base station the maximum number of non-orthogonal DMRS groups that the terminal can operate, and the base station sets the number of non-orthogonal DMRS groups to be operated, thereby preventing unnecessary PDSCH decoding. There is no need to calculate additionally. For example, if the terminal reports the maximum number of non-orthogonal DMRS groups that can be operated as 4, and the base station sets the number of non-orthogonal DMRS groups to be operated as 2, the terminal reports the number of non-orthogonal DMRS groups for the third non-orthogonal DMRS group. For the values ​​and the fourth non-orthogonal DMRS group The value may not be calculated.

[0129] Below, a method for indicating a non-orthogonal DMRS port to a terminal using the antenna port(s) field of downlink control information (DCI) is described.

[0130] According to one embodiment of the present disclosure, a base station can indicate to a terminal a non-orthogonal DMRS port for receiving a downlink data channel of the terminal through the Antenna port(s) (and number of layers field) field of DCI. At this time, as a first method for indicating to the terminal the non-orthogonal DMRS port using the antenna port(s) field of downlink control information (DCI), the present disclosure may include a method in which reserved rows in a DMRS port / pattern table related to the Antenna port(s) field of the DCI are used. Here, the DMRS port / pattern table may be a DMRS port / pattern table used to indicate an orthogonal DMRS port to a single terminal of SU-MIMO. Additionally, as a second method for indicating non-orthogonal DMRS ports to a terminal using the antenna port(s) field of downlink control information (DCI), the present disclosure may include a method of defining a new DMRS port / pattern table.

[0131] More specifically, regarding the first method, the Reserved rows existing in the DMRS antenna port table (e.g., Table 7.3.1.2.2-1 to Table 7.3.1.2.2-4A of the 3GPP TS38.212 standard) used by the base station to indicate the DMRS port for PDSCH reception to the terminal through the existing DCI (e.g., DCI format 1_1) can be utilized.

[0132] FIGS. 18 to 21 are diagrams illustrating examples of a method for indicating a non-orthogonal DMRS port to a terminal using the antenna port(s) field of downlink control information (DCI) according to various embodiments of the present disclosure. More specifically, FIGS. 18 to 21 are diagrams illustrating a method for utilizing a reserved row of a DMRS port / pattern table used to indicate an orthogonal DMRS port to a single terminal of SU-MIMO.

[0133] First, referring to FIG. 18, the table of FIG. 18 may include a value (1801) corresponding to a value of a DCI antenna port(s) field, information on the number of DMRS CDM groups without data corresponding to the value (1803), information on the configuration of DMRS ports (1805), and information on the number of front-load symbols (1807). In addition, it can be seen in FIG. 18 that the reserved rows of the DMRS port / pattern table used to indicate an orthogonal DMRS port to a single terminal of SU-MIMO are configured as rows for indicating a non-orthogonal DMRS port to a single terminal of SU-MIMO (1810). The DMRS port / pattern table of FIG. 18 may indicate a non-orthogonal DMRS port by using a reserved field of the NR DMRS Configuration Type1 (double symbol, i.e., DMRS in which two OFDM symbols are used for one DMRS) Table. At this time, non-orthogonal DMRS can utilize DMRS port of NR DMRS Configuration Type1. In addition, value 17-31 represents new reserved rows created according to the increase in the number of bits for configuring rows for indicating non-orthogonal DMRS ports (1820). Of course, all or part of value 17-31 can also be configured as rows for indicating non-orthogonal DMRS ports to a single terminal of SU-MIMO. In addition, the example of FIG. 18 is merely an example of configuring rows for indicating non-orthogonal DMRS ports to a single terminal of SU-MIMO, and the method of configuring rows for indicating non-orthogonal DMRS ports using reserved rows of the DMRS port / pattern table described in the present disclosure is not to be construed as being limited thereto.

[0134] Next, referring to FIG. 19, a DMRS pattern (1930) corresponding to the fourth row of FIG. 18 is shown, which represents an allocation of two non-orthogonal DMRS groups (1920, 1925) including two identical DMRS ports (port 1000 and port 1001), and a DMRS pattern (1940) corresponding to the sixth row of FIG. 18 is shown, which represents an allocation of two non-orthogonal DMRS groups (1920, 1925) including four identical DMRS ports (port 1000, port 1001, port 1002, and port 1003).

[0135] Next, referring to FIG. 20, a DMRS pattern corresponding to the 9th row of FIG. 18 is illustrated, which represents the allocation of two non-orthogonal DMRS groups (2020, 2025) containing four identical DMRS ports (port 1000, port 1001, port 1004, and port 1005).

[0136] Next, referring to FIG. 21, a DMRS pattern corresponding to the 16th row of FIG. 18 is illustrated, which represents the allocation of two non-orthogonal DMRS groups (2120, 2125) containing eight identical DMRS ports (port 1000, port 1001, port 1002, port 1003, port 1004, port 1005, port 1006, and port 1007).

[0137] FIGS. 22 to 25 are diagrams illustrating another example of a method for indicating a non-orthogonal DMRS port to a terminal using the antenna port(s) field of downlink control information (DCI) according to various embodiments of the present disclosure. More specifically, FIGS. 22 to 25 are diagrams illustrating a method for utilizing a reserved row of a DMRS port / pattern table used to indicate an orthogonal DMRS port to a single terminal of SU-MIMO. The DMRS port / pattern table of FIG. 22 may utilize a reserved field of an existing NR DMRS Configuration Type2 (double symbol) Table.

[0138] First, referring to FIG. 22, the table of FIG. 22 may include a value (2201) corresponding to a value of a DCI antenna port(s) field, information on the number of DMRS CDM groups without data corresponding to the value (2203), information on the configuration of DMRS ports (2205), and information on the number of front-load symbols (2207). In addition, in FIG. 22, it can be seen that the reserved rows of the DMRS port / pattern table used to indicate an orthogonal DMRS port to a single terminal of SU-MIMO are configured with rows for indicating a non-orthogonal DMRS port to a single terminal of SU-MIMO (2210). In addition, values ​​23-31 represent new reserved rows created according to an increase in the number of bits for configuring rows for indicating a non-orthogonal DMRS port (2220). It should be noted that all or part of values ​​23-31 may also be configured as rows for indicating non-orthogonal DMRS ports to a single SU-MIMO terminal. In addition, the example of FIG. 22 is merely an example of configuring rows for indicating non-orthogonal DMRS ports to a single SU-MIMO terminal, and the method of configuring rows for indicating non-orthogonal DMRS ports using reserved rows of the DMRS port / pattern table described in the present disclosure is not limited thereto.

[0139] Next, referring to FIG. 23, a DMRS pattern (2230) corresponding to the 8th row of FIG. 22 is shown, which represents the allocation of two non-orthogonal DMRS groups (2320, 2325) including four identical DMRS ports (ports 1000, 1001, 1002, and 1003), and a DMRS pattern (2340) corresponding to the 12th row of FIG. 22 is shown, which represents the allocation of two non-orthogonal DMRS groups (2320, 2325) including four identical DMRS ports (ports 1000, 1001, 1006, and 1007).

[0140] Next, referring to FIG. 24, a DMRS pattern corresponding to the 21st row of FIG. 24 is illustrated, which represents the allocation of two non-orthogonal DMRS groups (2420, 2425) containing eight identical DMRS ports (port 1002, port 1003, port 1004, port 1005, port 1008, port 1009, port 1010, and port 1011).

[0141] Next, referring to FIG. 25, there is shown a DMRS pattern corresponding to the 22nd row of FIG. 24, which represents the allocation of two non-orthogonal DMRS groups (2520, 2525) containing 12 identical DMRS ports (port 1000, port 1001, port 1002, port 1003, port 1004, port 1005, port 1006, port 1007, port 1008, port 1009, port 1010, and port 1011).

[0142] Next, we describe how a base station defines a new table to allocate non-orthogonal DMRS to terminals.

[0143] FIG. 26 is a diagram illustrating another example of a method for indicating a non-orthogonal DMRS port to a terminal using an antenna port(s) field of downlink control information (DCI) according to various embodiments of the present disclosure. Referring to FIG. 26, the table of FIG. 26 may include a value (2610) corresponding to a value of a DCI antenna port(s) field, a DMRS configuration type (2620) corresponding to the value, information on the number of DMRS CDM groups without data (2630), information on the configuration of DMRS ports (2640), and information on the number of front load symbols (2650). In particular, the table of FIG. 26 may be newly defined only for the purpose of knowing non-orthogonal DMRS ports, and at this time, when the non-orthogonal DMRS port of FIG. 26 is indicated, the terminal can determine based on which orthogonal DMRS design the non-orthogonal DMRS port is indicated through information (2620) about the Configuration Type of the table. In addition, the example of FIG. 26 is only an example of configuring rows for indicating a non-orthogonal DMRS port to a single terminal of SU-MIMO, and the method of the present disclosure is not limited to the form illustrated in FIG. 26.

[0144] Below, the downlink non-orthogonal DMRS reception operation of the terminal is described.

[0145] When a terminal is allocated a non-orthogonal DMRS port and its corresponding PDSCH, it can perform PDSCH channel estimation and equalization through various methods.

[0146] FIG. 27 is a diagram illustrating an example of a downlink non-orthogonal DMRS reception operation of a terminal according to various embodiments of the present disclosure. The terminal may schedule a PDSCH from a base station and receive DCI including information (e.g., an antenna port(s) field) for indicating a non-orthogonal DMDRS port for PDSCH reception on the PDCCH (2710). At this time, the terminal may identify a non-orthogonal DMDRS port for PDSCCH reception based on the information for indicating the non-orthogonal DMDRS port included in the DCI received on the PDCCH, and may receive the PDSCH through the identified non-orthogonal DMDRS port (2720).

[0147] FIG. 28 is a diagram illustrating another example of a downlink non-orthogonal DMRS reception operation of a terminal according to various embodiments of the present disclosure. More specifically, FIG. 28 is a diagram for a case in which an 8-layer non-orthogonal DMRS (layer non-orthogonal DMRS) based on two non-orthogonal DMRS groups is transmitted to a terminal having eight antenna ports (2810, 2820). A base station can indicate a non-orthogonal DMRS port using the antenna port(s) field present in DCI 1_1. When a terminal is indicated a non-orthogonal DMRS port, it performs channel estimation and equalization in parallel for each receiving antenna port associated with the non-orthogonal DMRS group indicated by the base station, thereby decoding a PDSCH. That is, when the terminal is assigned two non-orthogonal DMRS groups for eight antenna ports, the terminal can perform the receiving operation in parallel for each of the four DMRS ports (2810, 2820) associated with each of the two non-orthogonal DMRS groups.

[0148] The method of the present disclosure can effectively reduce the DMRS overhead that increases as a base station supports multiple layers for a terminal. Furthermore, by reducing the DMRS overhead, resource elements that can be used for purposes other than DMRS transmission can be secured, and the secured resource elements can be used for other resource allocations. Furthermore, the method of the present disclosure can have the effect of improving the Transport Block Error Rate (TBER) by lowering the code rate by increasing the use of PDSCH output coded bits.

[0149] FIG. 29 is a flowchart showing an example of a method of operating a terminal according to various embodiments of the present disclosure.

[0150] First, the terminal can provide information related to the terminal's receiving antenna port to the base station (2910).

[0151] Next, the terminal can transmit capability information including information on the maximum number of demodulation reference signal (DMRS) groups that the terminal can support to the base station (2920).

[0152] Thereafter, the terminal can receive configuration information including information on the number of DMRS groups set to the terminal from the base station (2930).

[0153] Thereafter, the terminal can receive, from the base station, at least one DMRS corresponding to the number of DMRS groups based on the configuration information, through different receiving antenna ports of the terminal each associated with the DMRS group (2940).

[0154] At this time, DMRS ports with the same or different port indices assigned to each of the DMRS groups are set, and different initialization sequences for generating DMRS sequences can be applied to each of the DMRS groups.

[0155] FIG. 30 is a flowchart illustrating an example of a method of operating a base station according to various embodiments of the present disclosure.

[0156] The base station can receive information related to the terminal's receiving antenna port from the terminal (3010).

[0157] Next, the base station can receive capability information from the terminal, including information on the maximum number of demodulation reference signal (DMRS) groups that the terminal can support (3020).

[0158] Next, the base station can transmit configuration information including information on the number of DMRS groups set to the terminal to the terminal (3030).

[0159] Thereafter, the base station can transmit at least one DMRS corresponding to the number of DMRS groups based on the setting information to the terminal (3040).

[0160] At this time, each of the DMRS groups is associated with a different receiving antenna port of the terminal, DMRS ports having the same or different port indices assigned to each of the DMRS groups are set, and different initialization sequences for generating DMRS sequences can be applied to each of the DMRS groups.

[0161] The methods according to the embodiments described in the claims or specification of the present disclosure may be implemented in the form of hardware, software, or a combination of hardware and software.

[0162] When implemented in software, a computer-readable storage medium storing one or more programs (software modules) may be provided. The one or more programs stored in the computer-readable storage medium are configured for execution by one or more processors within an electronic device. The one or more programs include instructions that cause the electronic device to execute methods according to embodiments described in the claims or specification of the present disclosure.

[0163] These programs (software modules, software) may be stored in random access memory, non-volatile memory including flash memory, read only memory (ROM), electrically erasable programmable read only memory (EEPROM), magnetic disc storage devices, compact disc-ROMs (CD-ROMs), digital versatile discs (DVDs) or other forms of optical storage devices, magnetic cassettes, or may be stored in memories formed by a combination of some or all of these. In addition, each configuration memory may include multiple copies.

[0164] Additionally, the program may be stored on an attachable storage device that is accessible via a communication network, such as the Internet, an intranet, a local area network (LAN), a wide area network (WAN), a storage area network (SAN), or a combination thereof. Such a storage device may be connected to a device implementing an embodiment of the present disclosure via an external port. Additionally, a separate storage device on the communication network may be connected to a device implementing an embodiment of the present disclosure.

[0165] In the specific embodiments of the present disclosure described above, components included in the disclosure are expressed singularly or plurally, depending on the specific embodiment presented. However, the singular or plural expressions are selected to suit the presented situation for convenience of explanation, and the present disclosure is not limited to singular or plural components. Components expressed in plural may be composed of singular elements, or components expressed in singular may be composed of plural elements.

[0166] While the detailed description of this disclosure has described specific embodiments, it should be understood that various modifications are possible without departing from the scope of this disclosure. Therefore, the scope of this disclosure should not be limited to the described embodiments, but should be defined not only by the scope of the claims described below, but also by equivalents thereof.

Claims

1. A method performed by a terminal (user equipment) in a wireless communication system, A step of providing information related to the receiving antenna port of the terminal to the base station; A step of transmitting capability information including information on the maximum number of demodulation reference signal (DMRS) groups that the terminal can support to the base station; A step of receiving configuration information including information on the number of DMRS groups set to the terminal from the base station; and A step of receiving, from the base station, at least one DMRS corresponding to the number of DMRS groups based on the configuration information, through different receiving antenna ports of the terminal each associated with the DMRS group; A method in which DMRS ports having the same or different port indices are set for each of the above DMRS groups, and different initialization sequences for generating DMRS sequences are applied to each of the above DMRS groups.

2. In paragraph 1, A method, wherein the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group among the above DMRS groups is the same, and the last DMRS group includes the number of receiving antenna ports remaining excluding the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group.

3. In paragraph 1, A method wherein the above configuration information further includes information on the relationship between each of the DMRS groups and different receiving antenna ports of the terminal.

4. In paragraph 1, The above different initialization sequences are generated differently based on the scrambling identifier, which is set to different values ​​for each DMRS group, or A method wherein the different initialization sequences are generated differently based on a DMRS group identifier parameter that is set to different values ​​for each DMRS group.

5. In the first paragraph, the method, Further comprising a step of receiving downlink control information (DCI) including a field related to the configuration of a DMRS port included in the DMRS group from the base station, Based on the above fields, information about the configuration of DMRS ports included in the DMRS group, information about the number of DMRS CDM (code division multiplexing) groups without data, and information about the number of front load symbols to which the DMRS is mapped are indicated, or A method in which, based on the above fields, information about the configuration of DMRS ports included in the DMRS group, information about the number of DMRS CDM (code division multiplexing) groups without the data, information about the number of front load symbols to which the DMRS is mapped, and information about the DMRS setting type are indicated.

6. A method performed by a base station in a wireless communication system, A step of receiving information related to a receiving antenna port of a terminal from the terminal; A step of receiving capability information including information on the maximum number of demodulation reference signal (DMRS) groups that the terminal can support from the terminal; A step of transmitting configuration information including information on the number of DMRS groups set to the terminal to the terminal; and A step of transmitting at least one DMRS corresponding to the number of DMRS groups based on the setting information to the terminal; Each of the above DMRS groups is associated with a different receiving antenna port of the terminal, A method in which DMRS ports having the same or different port indices are set for each of the above DMRS groups, and different initialization sequences for generating DMRS sequences are applied to each of the above DMRS groups.

7. In paragraph 6, A method, wherein the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group among the above DMRS groups is the same, and the last DMRS group includes the number of receiving antenna ports remaining excluding the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group.

8. In paragraph 6, A method wherein the above configuration information further includes information on the relationship between each of the DMRS groups and different receiving antenna ports of the terminal.

9. In paragraph 6, The above different initialization sequences are generated differently based on the scrambling identifier, which is set to different values ​​for each DMRS group, or A method wherein the different initialization sequences are generated differently based on a DMRS group identifier parameter that is set to different values ​​for each DMRS group.

10. In paragraph 6, the method, Further comprising a step of transmitting downlink control information (DCI) including a field related to the configuration of a DMRS port included in the DMRS group to the terminal, Based on the above fields, information about the configuration of DMRS ports included in the DMRS group, information about the number of DMRS CDM (code division multiplexing) groups without data, and information about the number of front load symbols to which the DMRS is mapped are indicated, or A method in which, based on the above fields, information about the configuration of DMRS ports included in the DMRS group, information about the number of DMRS CDM (code division multiplexing) groups without the data, information about the number of front load symbols to which the DMRS is mapped, and information about the DMRS setting type are indicated.

11. In a wireless communication system, in a terminal (user equipment), the terminal, Transmitter and receiver; and Including a controller connected to the above transmitter and receiver, The above controller, A step of providing information related to the receiving antenna port of the above terminal to the base station; A step of transmitting capability information including information on the maximum number of demodulation reference signal (DMRS) groups that the terminal can support to the base station; A step of receiving configuration information including information on the number of DMRS groups set to the terminal from the base station; It is configured to perform a step of receiving, from the base station, at least one DMRS corresponding to the number of DMRS groups based on the setting information, through different receiving antenna ports of the terminal each associated with the DMRS group, A terminal in which DMRS ports having the same or different port indices are assigned to each of the above DMRS groups, and different initialization sequences for generating DMRS sequences are applied to each of the above DMRS groups.

12. In paragraph 11, A terminal, wherein the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group among the above DMRS groups is the same, and the last DMRS group includes the number of receiving antenna ports remaining excluding the number of receiving antenna ports of the terminal corresponding to each DMRS group except for the last DMRS group.

13. In paragraph 11, A terminal, wherein the above configuration information further includes information on the relationship between each of the DMRS groups and different receiving antenna ports of the terminal.

14. In paragraph 11, The above different initialization sequences are generated differently based on the scrambling identifier, which is set to different values ​​for each DMRS group, or The above different initialization sequences are generated differently for each DMRS group based on the DMRS group identifier parameter, which is set to different values ​​for each DMRS group.

15. In a wireless communication system, there is a base station, Transmitter and receiver; and Including a controller connected to the above transmitter and receiver, The above controller, A step of receiving information related to the receiving antenna port of the terminal from the terminal; A step of receiving capability information including information on the maximum number of demodulation reference signal (DMRS) groups that the terminal can support from the terminal; A step of transmitting configuration information including information on the number of DMRS groups set to the terminal to the terminal; The terminal is configured to perform a step of transmitting at least one DMRS corresponding to the number of DMRS groups based on the setting information, Each of the above DMRS groups is associated with a different receiving antenna port of the terminal, A base station, wherein DMRS ports having the same or different port indices are set for each of the above DMRS groups, and different initialization sequences for generating DMRS sequences are applied to each of the above DMRS groups.

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