KR102371961B1 - Method and apparatus for transmitting reference signal, method and apparatus for measuring and reporting channel state information, and method for configuring the same - Google Patents

Abstract

A method for a base station to transmit channel state information (CSI)-reference signal (RS) in a multiple input multiple output (MIMO) antenna system is provided. The base station periodically transmits the CSI-RS for the first CSI to the terminal. The base station requests transmission of the second CSI from the terminal in the first subframe. And the base station, when a CSI-RS occasion (occasion) is configured, from the second subframe or the second subframe, which is a subframe after the first offset configured for CSI-RS transmission from the first subframe Until, the CSI-RS for the second CSI is transmitted to the UE during the duration of the CSI-RS occasion.

Description

A method and apparatus for transmitting a reference signal, a method and apparatus for measuring and reporting channel state information, and a setting method for the same THE SAME}

The present invention relates to a method and apparatus for transmitting a reference signal, a method and apparatus for measuring and reporting channel state information, and a setting method therefor.

Full-dimensional (FD) multiple input multiple output (MIMO) transmission uses a two-dimensional antenna array to transmit horizontal domain/direction or azimuth domain/direction (hereinafter referred to as 'horizontal domain') And by forming a beam adaptively for a vertical domain/direction, zenith domain/direction, or elevation domain/direction (hereinafter referred to as a 'vertical domain'), frequency efficiency is improved, and interference with neighboring cells is mitigated , improving cell coverage, and the like.

For FD-MIMO transmission, like the current MIMO transmission in which beamforming is adaptive only in the horizontal domain, a base station or a repeater includes RI (rank indicator), CQI (channel quality indicator), PMI (precoding matrix indicator), M Channel state information (CSI: channel state information) including positions of the M selected subbands, or preferred subbands, hereinafter 'selected subbands') is reported from the terminal (or feedback, hereinafter 'reported') ') should be taken.

Meanwhile, the UE needs to acquire a MIMO channel for CSI measurement. When the base station sets a CSI-RS (reference signal) or NZP (non-zero power) CSI-RS and transmits the CSI-RS accordingly, the terminal receives the CSI-RS and estimates the MIMO channel. The base station may set an energy per resource element (EPRE) of the CSI-RS in consideration of channel estimation performance using the CSI-RS and interference on a neighboring cell due to CSI-RS transmission. The UE measures the above-mentioned various types of CSI (eg, RI, CQI, PMI, selected subband, etc.) using the channel estimated from the CSI-RS and reports it to the base station. The base station performs link adaptation using the CSI. Including scheduling (or resource allocation) is performed. CSI-RS transmission described below means that the base station transmits to the terminal, and may include the terminal receiving the CSI-RS from the base station. The CSI report described below means that the terminal transmits the measured CSI to the base station, and may include the base station receiving the CSI from the terminal. The 'current standard' referred to below means the current standard of ^3rd generation partnership project (3GPP) long term evolution (LTE) Release 12.

The CSI-RS is a downlink reference signal transmitted by the base station for the purpose of the terminal measuring a channel required for downlink CSI measurement, and was introduced in 3GPP LTE Release 10. The CSI-RS is also referred to as an NZP CSI-RS to distinguish it from a zero-power (ZP) CSI-RS to be described later. In the 3GPP LTE Release 8/9 system, a cell-specific reference signal (CRS) was used to measure the CSI of the UE, but from 3GPP LTE Release 10, it is higher than the conventional CRS to support downlink transmission of up to 8 layers. It is necessary to introduce a new reference signal for channel estimation having a low density.

The CSI-RS is configured to the UE through user equipment (UE)-specific radio resource control (RRC) signaling, and the number of CSI-RS antenna ports configurable to the UE is 1, 2, 4, and 8. The CSI-RS is transmitted over the entire system bandwidth, and two resource elements (REs) are used per physical resource block (PRB) pair for CSI-RS transmission of each CSI-RS antenna port. Two CSI-RS antenna ports are CDM (code division multiplexing) in two REs spanning two OFDM symbols separated by two consecutive orthogonal frequency division multiplexing (OFDM) symbols (or one OFDM symbol) of the same subcarrier. , has a density of 1 RE/CSI-RS antenna port. The transmission period on the time axis of the CSI-RS may be set to 5, 10, 20, 40, or 80 ms. The mapping of REs through which the CSI-RS is transmitted follows a pattern defined by a configuration parameter (CSI-RS configuration) for each number of antenna ports.

The CSI-IM (interference measurement) resource is a resource for the UE to measure interference required for CSI measurement, and was introduced in 3GPP LTE Release 11. The RE location in the PRB pair for CSI-IM is indicated through a CSI-RS configuration configuration parameter corresponding to the number of four CSI-RS antenna ports. The transmission period on the time axis of the CSI-IM may be set to 5, 10, 20, 40, or 80 ms, like the NZP CSI-RS.

When the UE performs physical downlink shared channel (PDSCH) rate matching, it is assumed that the PDSCH is not mapped to the RE configured as the ZP CSI-RS. ZP CSI-RS can be mainly used for two purposes. First, the base station does not transmit a signal (or performs muting) in the RE in which the CSI-RS of the neighboring cell is transmitted, thereby improving the CSI-RS measurement performance of the UE for the neighboring cell. . In this case, the base station may inform the UE of REs to which muting is applied through the ZP CSI-RS configuration. Second, the ZP CSI-RS may be configured for the purpose of configuring a resource for measuring an interference signal of the UE. The CSI-IM resource used for measuring the interference signal may be configured only within the ZP CSI-RS resource region configured for the UE.

An object of the present invention is to provide a method and apparatus for transmitting CSI-RS required for CSI measurement for FD-MIMO transmission.

In addition, the problem to be solved by the present invention is to provide a method and apparatus for measuring and reporting CSI using the CSI-RS when receiving it.

According to an embodiment of the present invention, there is provided a method in which a base station transmits channel state information (CSI)-reference signal (RS) in a multiple input multiple output (MIMO) antenna system. The CSI-RS transmission method of the base station includes: periodically transmitting a CSI-RS for a first CSI to a terminal; requesting transmission of a second CSI from the terminal in a first subframe; And when a CSI-RS occasion is configured, from the second subframe that is a subframe after the first offset configured for CSI-RS transmission from the first subframe, or from the second subframe to the second subframe, the CSI - Transmitting the CSI-RS for the second CSI to the UE during the duration of the RS occasion.

The first CSI may be CSI for one of a horizontal domain and a vertical domain, and the second CSI may be CSI for the other domain.

In the step of requesting transmission of the second CSI from the terminal, when it is determined that at least one of an update for the second CSI and a feedback on the second CSI is necessary, the transmission of the second CSI to the terminal It may include a requesting step.

The requesting for transmission of the CSI-RS for the second CSI may include: receiving a request for transmission of the CSI-RS for the second CSI from the terminal in a third subframe; and in the first subframe, which is a subframe after a second offset configured for CSI-RS transmission from the third subframe, requesting the UE to transmit the second CSI.

Receiving the request for transmission of the CSI-RS for the second CSI includes, through at least one of a physical uplink control channel (PUCCH) and a medium access control (MAC) control element (CE), CSI for the second CSI - It may include the step of receiving the transmission request of the RS from the terminal.

The CSI-RS transmission request for the second CSI is, for at least one of reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and channel quality indicator (CQI). When the value or the degree of change of the value is equal to or greater than the threshold, it may be transmitted by the terminal.

In the step of transmitting the CSI-RS for the second CSI, the CSI-RS for the second CSI is not transmitted in a subframe in which the CSI-RS for the first CSI is transmitted, or the first CSI is transmitted. and configuring a CSI-RS transmission resource for the second CSI so as not to overlap with a CSI-RS transmission resource for the CSI-RS.

The method for configuring the base station may further include configuring information on correlation between the periodic CSI report of the terminal and the aperiodic CSI report of the terminal to the terminal through signaling between the base station and the terminal.

The CSI measurement for the aperiodic CSI report of the terminal may be performed by the terminal to which the mutual association information is configured, based on the CSI measurement for the periodic CSI report of the terminal.

In addition, according to another embodiment of the present invention, there is provided a method for a base station to set measurement and report of channel state information (CSI) to a terminal in a multiple input multiple output (MIMO) antenna system. The method for configuring the base station includes: grouping a plurality of CSI-RS antenna ports to create a plurality of CSI-RS antenna port groups; When a CSI report for a first CSI-RS antenna port group among the plurality of CSI-RS antenna port groups is requested from the terminal, information indicating the first CSI-RS antenna port group is transmitted through downlink (DL). including in a CSI request field of a downlink control information (DCI) format; and requesting an aperiodic CSI report from the UE by using the CSI request field of the DCI.

In the method for configuring the base station, when a CSI report for at least one of a horizontal domain and a vertical domain is requested from the terminal, information corresponding to the at least one domain is added to the CSI request field of the DL DCI format. It may further include the step of including.

The method for configuring the base station includes, when the UE intends to measure the second domain CSI based on the first domain CSI among the first domain CSI and the second domain CSI, the first CSI for the first domain CSI setting the first CSI process among a process and a second CSI process for the second domain CSI as a reference CSI process; and informing the UE of a process identifier indicating the first CSI process as information of the reference CSI process.

The first domain CSI may be one of horizontal domain CSI and vertical domain CSI, and the second domain CSI may be the other one of the horizontal domain CSI and the vertical domain CSI.

The setting of the first CSI process as the reference CSI process may include: configuring the reference CSI process for one first CSI measurement subframe set to the terminal; and configuring the second CSI process for a plurality of second CSI measurement subframe sets to the UE.

The second domain CSI for the plurality of second CSI measurement subframe sets is measured by the terminal based on the first domain CSI for the first measurement subframe set measured through the reference CSI process. can

Configuring the first CSI process as a reference CSI process may include configuring the reference CSI process and the second CSI process for a plurality of CSI measurement subframe sets to the terminal.

The second domain CSI for each of the plurality of CSI measurement subframe sets is measured based on the first domain CSI for each of the plurality of CSI measurement subframe sets measured by the terminal through the reference CSI process can be

In addition, according to another embodiment of the present invention, there is provided a method in which a base station sets a process of channel state information (CSI) to a terminal in a multiple input multiple output (MIMO) antenna system. The method for configuring the base station includes configuring a plurality of CSI-RS resources when operating in the first CSI-RS mode in which a plurality of reference signal (CSI-RS) antenna ports have the same beam width and beam direction. including a plurality of first identifiers indicating and a second identifier indicating one CSI-IM (interference measurement) resource configuration in one first CSI process configuration information; setting the first CSI process configuration information to the terminal; and receiving, from the terminal, CSI measured according to the first CSI process configuration information.

The number of the plurality of CSI-RS antenna ports included in the plurality of CSI-RS resources corresponding to the plurality of first identifiers is determined by the terminal, the plurality of first identifiers being included in the first CSI process configuration information It may be assigned according to an order or values of the plurality of first identifiers.

The method for configuring the base station includes a plurality of CSI-RS resource configurations indicating a plurality of CSI-RS resource configurations when all or part of the plurality of CSI-RS antenna ports are operated in the second CSI-RS mode to have different beam directions. including a third identifier and a plurality of fourth identifiers indicating a plurality of CSI-IM resource configurations in one second CSI process configuration information; setting the second CSI process configuration information to the terminal; and receiving, from the terminal, CSI measured according to the second CSI process configuration information.

The method for configuring the base station may include: selecting one of the first CSI-RS mode and the second CSI-RS mode; and including information indicating the selected mode in configuration information corresponding to the selected mode among the first CSI-RS process configuration information and the second CSI-RS process configuration information.

When operating in the second CSI-RS mode, a Doppler shift and a Doppler spread between a first CSI-RS antenna port and a DM-RS antenna port among the plurality of CSI-RS antenna ports are performed. spread), average delay, and quasi co-location (QCL) for delay spread are satisfied, the UE may assume.

The first CSI-RS antenna port may be a CSI-RS antenna port belonging to a CSI-RS resource indicated by a first identifier selected by the terminal among the plurality of third identifiers.

When operating in the second CSI-RS mode, Doppler shift, Doppler spread, average delay, and delay spread between a first CSI-RS antenna port and a first DM-RS antenna port among the plurality of CSI-RS antenna ports The UE may assume that the QCL for up to 4 of them is satisfied.

The first CSI-RS antenna port is, among the plurality of third identifiers, for a CSI process corresponding to QCL information configured through physical layer signaling from the base station for the terminal to receive a physical downlink shared channel (PDSCH). It may be a CSI-RS antenna port belonging to a CSI-RS resource indicated by the third identifier selected by the terminal.

The first DM-RS antenna port may be a DM-RS antenna port belonging to a PDSCH transmission resource allocated by the DL DCI format including the QCL information.

Each of the plurality of third identifiers and each of the plurality of fourth identifiers may form a pair according to an order included in the second CSI process configuration information.

The terminal measures channels for a plurality of beams using CSI-RSs of a plurality of CSI-RS antenna ports corresponding to the plurality of third identifiers, and the plurality of channels that are paired with the plurality of third identifiers Measuring interferences for the plurality of beams in a resource defined for a plurality of CSI-RS antenna ports corresponding to a fourth identifier, and selecting at least one of the plurality of beams using the measured channels and interferences, CSI for each of the selected beams may be measured.

The receiving of the CSI measured according to the second CSI process configuration information may include, when the selected beam is singular, a third identifier corresponding to the selected beam among the plurality of third identifiers for the selected beam. Receiving from the terminal together with CSI; and when there are a plurality of selected beams, receiving a bitmap indicating a third identifier corresponding to the selected beam among the plurality of third identifiers, along with CSI for the selected beam, from the terminal. there is.

According to an embodiment of the present invention, a method and apparatus for transmitting CSI-RS for FD-MIMO transmission using multiple antennas, and a method and apparatus for measuring and reporting CSI using the CSI-RS may be provided. .

In addition, according to an embodiment of the present invention, CSI-RS can be effectively transmitted, and CSI can be effectively measured and reported in consideration of overhead, system performance, two-dimensional antenna array structure and channel characteristics thereof.

In addition, according to an embodiment of the present invention, the system performance of FD-MIMO can be improved.

1A, 1B, and 1C are diagrams illustrating a method of transmitting a CSI-RS in association with a CSI request according to an embodiment of the present invention.
2 is a diagram illustrating a method of reporting CSI in association with periodic CSI reporting and aperiodic CSI reporting according to an embodiment of the present invention.
3A and 3B are diagrams illustrating a CSI measurement restriction method applied to the time domain according to an embodiment of the present invention.
4 is a diagram illustrating a base station according to an embodiment of the present invention.
5 is a diagram illustrating a terminal according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art to which the present invention pertains can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, a terminal is a mobile terminal (MT), a mobile station (MS), an advanced mobile station (AMS), a high reliability mobile station (HR-MS) ), a subscriber station (subscriber station, SS), a portable subscriber station (PSS), an access terminal (AT), user equipment (UE), and the like, and may refer to a terminal, MT, It may include all or some functions of MS, AMS, HR-MS, SS, PSS, AT, UE, and the like.

In addition, the base station (base station, BS), an advanced base station (advanced base station, ABS), a high reliability base station (high reliability base station, HR-BS), a Node B (node B), an advanced node B (evolved node B) , eNodeB), access point (access point), radio access station (radio access station, RAS), base transceiver station (BTS), MMR (mobile multihop relay)-BS, a relay that serves as a base station (relay node) , RN), a high reliability relay station (HR-RS) that serves as a base station, may refer to a repeater, a macro base station, a small base station, etc., BS, ABS, HR-BS, NodeB, eNodeB, It may include all or part of the functions of an access point, RAS, BTS, MMR-BS, RN, HR-RS, repeater, macro base station, small base station, and the like.

1. Two-dimensional antenna array virtualization method

CSI items to be measured by the UE and reported to the base station may include RI, PMI, CQI, and selected subband index(s). In general, when a base station transmits a signal (or a physical channel, hereinafter referred to as a 'signal') to a terminal, the MIMO channel experienced over the radio has as many rows as the number of receive antennas of the terminal and as many columns as the number of transmit antennas of the base station. It can be expressed as a matrix. The i-th row and j-th column components of the MIMO channel matrix mean a channel value between the i-th receive antenna (or antenna element, radiation element) and the j-th transmit antenna (or antenna element, radiation element).

On the other hand, the base station is an antenna element (or radiation element, hereinafter collectively referred to as 'antenna element') constituting the transmit antenna array and an antenna port (AP), which is a logical multi-input unit of a baseband for signal transmission. ), can have two virtualization (virtualization) processes.

A signal of each antenna port is input to a single or a plurality of transceiver units (TXRUs) through an antenna port virtualization process, and goes through a process within the TXRU. The signal of each TXRU processed in this way is input as a single or a plurality of antenna components (or a unit including an antenna component, hereinafter collectively referred to as an 'antenna component') through the TXRU virtualization process. Signals processed up to each antenna component in this way are propagated through a radio channel.

As an example of an antenna port virtualization method, a signal of a single or a plurality of antenna ports is multiplied by a weight value having a magnitude and/or a phase, and a signal obtained by adding the signals of each antenna port multiplied by the weight value in this way is input to the TXRU There is a way. Here, the signal of the antenna port may be virtualized into a single or a plurality of TXRUs, and one TXRU may receive the virtualized signal after being output from the single or a plurality of antenna ports.

As an example of a TXRU virtualization method, a single or a plurality of TXRU output signals are multiplied by a weight value having a magnitude and/or a phase, and a signal obtained by adding the output signals of each TXRU multiplied by the weight value in this way is input to the antenna component. there is. Here, the output signal of the TXRU may be virtualized with a single or a plurality of antenna components, and one antenna component may receive a virtualized signal after being output from a single or a plurality of TXRUs.

In this way, each antenna port is virtualized into each antenna component and transmitted to the terminal, and each antenna port can form a beam in a specific direction through virtualization. According to the virtualization method, it is possible to form beams of all antenna ports in the same direction, form beams of all antenna ports in different directions, or form the same beam only between some antenna ports. In the baseband, in consideration of an effective MIMO channel in which the antenna port of the base station is input and the reception antenna (or reception antenna port, hereinafter referred to as 'reception antenna') of the terminal is output, beamforming or free Precoding is performed. If different virtualizations are applied, the radio channels may be the same but effective MIMO channels in the baseband may have different values.

The above-described virtualization method may include the following two methods (method M100 and method M101).

Method M100 is a virtualization method in which each antenna port has a different transmit vertical direction and/or a different transmit horizontal direction. Here, the vertical direction may be replaced with a Zenith angle, an elevation angle, a vertical angle, or a tilting angle, and the horizontal direction may be replaced with an azimuth angle, a horizontal angle, or a bearing angle.

Method M101 is a virtualization method in which all antenna ports have the same transmit vertical direction and/or the same transmit horizontal direction.

CSI-RS AP 2 > CSI-RS AP 3과 같은 순서를 가질 수 있다. 해당 단말을 위해서는 기지국이 CSI-RS AP 1을 통해 신호를 전송하는 것이 효율적일 수 있다. 반면에, 방법 M101은, 각 안테나 포트가 동일한 송신 방향을 갖도록 가상화하므로, 단말이 수신하는 각 안테나 포트의 신호 크기 차이는 작을 수 있다. 따라서 방법 M101은, 모든 안테나 포트를 이용하여 빔을 형성하는 전송 방법에 적합하다.Method M100 virtualizes each antenna port to have a different transmission vertical direction and/or a different transmission horizontal direction (hereinafter, 'transmission vertical direction and/or transmission horizontal direction' is referred to as 'transmission direction'), so that the terminal A difference in magnitude of a signal received from an antenna port may be large. Therefore, the method M100 is suitable for forming a beam using some antenna ports having a large received signal or transmitting each antenna port corresponding to candidate beams so that the terminal can select an optimal beam. For example, assuming that the base station configures four antenna ports in the vertical domain, the signal strength of each CSI-RS antenna port (hereinafter, 'CSI-RS AP') received by any one terminal is CSI-RS AP 1 > CSI-RS AP 0

CSI-RS AP 2 > CSI-RS AP 3 may have the same order. For the corresponding terminal, it may be efficient for the base station to transmit a signal through the CSI-RS AP 1 . On the other hand, since the method M101 virtualizes each antenna port to have the same transmission direction, the difference in signal magnitude between each antenna port received by the terminal may be small. Therefore, the method M101 is suitable for a transmission method in which a beam is formed using all antenna ports.

Meanwhile, the above-described virtualization method (eg, method M100, method M101) may be used UE-specifically or UE-group-specifically.

On the other hand, the above-described virtualization method can be used transparently from the viewpoint of the terminal. That is, the UE may perform a series of processes such as CSI-RS reception and channel estimation, CSI measurement and reporting, and PDSCH reception regardless of which virtualization is applied or without information related thereto.

2. CSI-RS transmission and its setting method, and other related methods

As described above, in order for the terminal to obtain a channel between each antenna port of the base station and the reception antenna, it must receive the CSI-RS transmitted by the base station and estimate the channel therefrom. At this time, the terminal estimates a channel from an antenna port configured as a CSI-RS AP by the base station among antenna ports that can be configured by the base station, measures CSI using this, and reports it to the base station. For example, assume that the base station can configure four antenna ports from the base station point of view. When the base station transmits signals by setting only two antenna ports as CSI-RS APs to terminal A1, terminal A1 may estimate channels for the two CSI-RS APs and perform CSI measurement and reporting using them. When the base station sets all four antenna ports as CSI-RS APs and transmits signals to the terminal B1, the terminal B1 estimates channels for the four CSI-RS APs and uses them to perform CSI measurement and reporting. .

On the other hand, when the base station has a large number of antenna ports, the beam can be precisely formed to improve system performance by mitigating intra-cell interference and inter-cell interference. can However, since the base station must increase the number of CSI-RS APs accordingly, the number of resources (or REs) capable of transmitting data can be reduced, thereby reducing the degree of system performance improvement. Therefore, there is a need for a CSI-RS transmission method capable of reducing CSI-RS overhead while maintaining the accuracy of CSI reported and received by the base station. In addition, CRS, UE-specific reference signal (UE-RS), demodulation reference signal (DM-RS), PRS currently used in 3GPP LTE Release 12 standards (including 3GPP LTE Release 8 standards to 3GPP LTE Release 12 standards) (positioning reference signal), MBSFN (multicast broadcast single frequency network) RS, PCFICH (physical control format indicator channel), PDCCH (physical downlink control channel), and PHICH (physical hybrid-ARQ indicator channel) control channel region including a control channel region ( Since it may be impossible to allocate a large number of additional CSI-RS resources (or REs) to one transmission time interval (TTI) or subframe by avoiding the RE corresponding to the control channel region), CSI-RS for solving this A method of transmission is required.

A downlink (DL) subframe in which a signal of a CSI-RS AP is transmitted (or DL TTI, hereinafter a 'subframe in which a signal of a CSI-RS AP is transmitted' is referred to as a 'CSI-RS subframe') The CSI-RS transmission method may include the following methods (method M200, method M201).

Method M200 is a method of transmitting signals of all CSI-RS APs in one CSI-RS subframe. Method M201 groups CSI-RS APs, and transmits signals of CSI-RS APs belonging to each CSI-RS AP group (hereinafter 'CSI-RS APG') in different CSI-RS subframes for each CSI-RS APG. way.

In method M201, the size of each CSI-RS APG (or CSI-RS AP subset, hereinafter referred to as 'CSI-RS APG') may be different. Also, in method M201, CSI-RS APs belonging to all CSI-RS APGs may not configure all CSI-RS APs. In such a case, method M201 may include method M201-1A.

Method M201-1A is a CSI-RS APG with CSI-RS APs for antenna ports belonging to one row listed in a horizontal domain and CSI-RS APs for antenna ports belonging to one column listed in a vertical domain as another CSI- This is a method of transmitting CSI-RS by configuring RS APG. As a CSI-RS configuration method for method M201-1A, when the base station configures each CSI-RS APG, antenna port array domain information including at least a horizontal domain and a vertical domain is transmitted for configuration of a terminal related thereto There is a way to include it in higher-layer signaling.

Method M201 is a CSI-RS configuration method and may include the following two methods (method M201-2A, method M201-2B).

Method M201-2A is a method of configuring a plurality of CSI-RS APGs using a plurality of CSI processes. Method M201-2B is a method of configuring multiple CSI-RS APGs using CSI-RS occasions.

Method M201-2A is a CSI-RS-ConfigNZP ( Alternatively, it is a method of configuring a CSI-RS AP belonging to each CSI-RS APG through NZP CSI-RS resource configuration).

When method M201-1A is configured using method M201-2A, two CSI processes are established. Among the two CSI processes, one CSI process may configure a CSI-RS APG for the horizontal domain, and a CSI-RS APG for the vertical domain may be configured using the NZP CSI-RS of the other CSI process. When method M201-2A is used for method M201-1A, array domain information of corresponding NZP CSI-RS APs may be included in CSI-Process IEs (information elements) or CSI process configuration information, and this information is at least horizontal It may include information on domains and vertical domains. For measurement and reporting of CSI assuming that PDSCH is transmitted through NZP CSI-RS APs corresponding to all or part of a CSI process among a plurality of CSI processes, association/association information between CSI processes is CSI It may be included in the process or CSI-RS configuration. The UE may measure CSI for a plurality of associated CSI processes simultaneously or interdependently by using this information. For example, in the case of configuring the CSI-RS for the method M201-1A, the base station may configure the association for two CSI processes corresponding to the horizontal and vertical domains using association information. Meanwhile, the base station csi-IM-ConfigId (or CSI-IM resource configuration ID) is set identically, or csi-IM-ConfigId (or CSI-IM resource configuration ID) corresponding to CSI-IM having the same CSI-RS subframe configuration is set for a plurality of CSI processes. can be set.

In method M201-2B, in order to configure one CSI-RS resource for a plurality of CSI-RS APGs, a discovery reference signal (DRS) occasion configuration concept applied to small cell enhancement (SCE) will be borrowed. can For convenience of description, this is referred to as CSI-RS occasion configuration. The CSI-RS occasion configuration may include, at least, each CSI-RS subframe configuration in which multiple CSI-RS APGs can be transmitted. In addition, the CSI-RS occasion configuration may further include a period and offset information in which the CSI-RS occasion is repeated, and a CSI-RS resource configuration. In addition, for CSI-RS APG configuration in CSI-RS occasion, CSI-RS occasion configuration includes the number of CSI-RS APGs, CSI-RS APG ID of each CSI-RS APG, CSI-RS AP number, CSI-RS The transmission resource may further include array domain information described in method M201-2A. Additionally, the CSI-RS occasion configuration may further include a CSI-IM resource configuration or a CSI-IM resource configuration ID (eg, csi-IM-ConfigId) for measuring interference within a CSI-RS occasion.

Meanwhile, a method for an antenna port to which virtualization is applied to transmit CSI-RS to have different transmission directions may include the following methods (method M210 and method M211).

Method M210 is a method in which the base station transmits CSI-RS AP signals for all antenna ports in each CSI-RS subframe regardless of the transmission direction. Method M211 is a method in which the base station transmits signals of the CSI-RS AP for antenna ports having the same transmission direction in the same CSI-RS subframe.

In method M210, the base station transmits signals of the CSI-RS APs for all antenna ports in each CSI-RS subframe, regardless of the transmission direction. For example, the base station configures 4 antenna ports (eg, antenna ports 0~3), and virtualizes antenna ports 0 and 1 to have a tilting angle of 102 degrees, and antenna ports 2 and 3 to have a tilting angle of 90 degrees. Suppose we are virtualizing. In this case, according to method M210, signals of four CSI-RS APs may be transmitted together in a CSI-RS subframe.

Method M211 is a method in which only antenna ports having the same transmission direction transmit a signal of each CSI-RS AP in the same CSI-RS subframe. If the same assumptions as in the example for method M210 described above are applied to method M211, CSI-RSs for antenna ports 0 and 1 are transmitted through two CSI-RS APs in one CSI-RS subframe, and antenna port 2 CSI-RSs for and 3 are transmitted through two CSI-RS APs in different CSI-RS subframes.

A method of transmitting signals of antenna ports having different transmission directions in different CSI-RS subframes according to method M211 may include the following two methods (method M211-1A, method 211-1B).

Method M211-1A is a method in which the base station sets CSI-RS subframe configurations as many as the number of different transmission directions, and transmits signals of CSI-RS APs in the corresponding transmission directions in the corresponding CSI-RS subframes.

Method M211-1B is a method in which the base station configures one CSI-RS subframe configuration and transmits the CSI-RS by applying virtualization differently depending on the transmission direction in each CSI-RS subframe. Method M211-1B may be divided into the following two methods (method M211-1B-1, method M211-1B-2) according to whether the base station transmits virtualization configuration information to the terminal.

Method M211-1B-1 is a method in which the base station uses virtualization without virtualization configuration information to the terminal. Method M2111-1B-2 is a method in which the base station notifies the terminal of virtualization setting information and uses virtualization.

In method M211-1B-2, the base station may define a virtualization pattern in notifying the terminal of virtualization configuration information. Here, the virtualization pattern may include information indicating a virtualization weight applied to each CSI-RS subframe or information indicating a transmission direction according to virtualization. In order for the base station to define a virtualization pattern, the number of CSI-RS subframes as length information and a virtualization indicator (VI) applied to each CSI-RS subframe for CSI-RS subframes of the corresponding length are displayed as virtualization pattern information. can be included in The base station may set virtualization pattern information to the terminal through higher-layer signaling and/or physical layer signaling, and may change and reconfigure it. In order to reduce signaling overhead when the base station resets virtualization pattern information, a virtualization pattern set composed of a certain number of virtualization patterns may be defined, and only an indicator (or identifier) of the corresponding virtualization pattern may be transmitted. The base station may include, in the virtualization pattern set information, at least the virtualization pattern set size, virtualization pattern information as much as the virtualization pattern set size (which may be the number of the CSI-RS subframes), and a virtualization pattern indicator.

The CSI-RS transmission method according to the periodicity or instantaneousness of CSI-RS transmission may include the following three methods (method M220, method M221, and method M222).

Method M220 is a method in which the base station periodically transmits CSI-RS. Method M221 is a method in which the base station instantaneously transmits a CSI-RS. When the base station instantaneously transmits the CSI-RS, the instantaneousness may correspond to the viewpoint of the terminal. That is, even if the base station periodically transmits the CSI-RS from the system point of view, the base station may configure the CSI-RS so that the corresponding terminal assumes that the corresponding CSI-RS is transmitted instantaneously from the point of view of one terminal.

Method M222 is a method in which the base station periodically transmits the CSI-RS, and additionally transmits the CSI-RS instantaneously as needed.

In the current standard, the base station sets the CSI-RS subframe configuration including the CSI-RS transmission period and offset to each terminal through higher-layer signaling, and periodically transmits the CSI-RS accordingly. This corresponds to a method in which method M200 and method M220 are combined (hereinafter, 'method M220-1A').

A method combining method M201 and method M220 (hereinafter 'method M220-1B') may also be used. When application of method M201-2B is considered for method M201, the base station may set the period and offset information for the CSI-RS occasion to the terminal through higher-layer signaling, and accordingly, the base station may In each CSI-RS subframe in the CSI-RS occasion, the signal of the CSI-RS APG belonging to the corresponding CSI-RS APG may be transmitted for each application period. If the application of method M201-2A is considered for method M201, the base station can set the transmission period and offset of the corresponding CSI-RS through the CSI-RS subframe configuration of the NZP CSI-RS configuration belonging to each CSI process to the terminal. there is. Here, the base station may set the transmission period of the CSI-RS APG differently through the NZP CSI-RS configuration belonging to each CSI process. For example, the base station may set a transmission period of a horizontal domain CSI-RS APG to be shorter than a transmission period of a vertical domain CSI-RS APG in order to reduce overhead due to CSI-RS transmission.

Method M221 is a method for the base station to instantaneously transmit a CSI-RS, and may include the following two methods (method M221-1A, method M221-1B). Method M221-1A is a method in which the base station transmits the CSI-RS in association with the CSI request of the base station. Method M221-1B is a method in which the base station transmits the CSI-RS according to the CSI-RS transmission request of the terminal.

Method M221-1A will be described with reference to FIGS. 1A, 1B, and 1C. Specifically, FIG. 1A is a diagram illustrating a case in which a CSI-RS is configured in one CSI-RS subframe. 1b shows that a CSI-RS occasion is set, and the base station transmits CSI-RS in N consecutive DL subframes (including (n1+k1) th DL subframes) from the (n1+k1)-th DL subframe. It is a diagram showing a case where 1c shows that a CSI-RS occasion is set, and the base station transmits CSI-RS in N consecutive DL subframes up to (n1+k1) th DL subframe (including (n1+k1) th DL subframe). It is a diagram showing a case where

When the base station transmits the CSI request to the UE in the n1-th DL subframe, from the (n1+k1)-th DL subframe or from the (n1+k1)-th subframe, the CSI-RS associated with the CSI request is transmitted. . Here, k1 is an integer greater than or equal to 0 and may be defined in advance or set through higher-layer signaling.

Meanwhile, as illustrated in FIG. 1A , when the CSI-RS is configured in one CSI-RS subframe, the base station may transmit the CSI-RS in the (n1+k1)-th DL subframe. For example, as illustrated in FIG. 1A , when a base station transmits a CSI request to a UE in an n1 th DL subframe, a CSI-RS is transmitted in an (n1+k1) th subframe.

On the other hand, as illustrated in FIGS. 1B and 1C , when a plurality of CSI-RS subframes of the above-described CSI-RS occasion are configured, transmission of a plurality of CSI-RS subframes is required for a plurality of CSI processes. , or otherwise, if there is a need of the base station, the base station from (n1 + k1) th DL subframe (FIG. 1b) or (n1 + k1) th DL subframe (FIG. 1C) N consecutive DL subframes may transmit CSI-RS. where N is an integer greater than or equal to 1. For example, as illustrated in FIG. 1B , when the base station transmits a CSI request to the UE in the n1 th DL subframe, from the (n1+k1) th subframe to the (n1+k1+N-1) th subframe CSI-RS is transmitted until the frame. For another example, as illustrated in FIG. 1C , when the base station transmits a CSI request to the UE in the n1-th DL subframe, from (n1+k1-N+1)-th subframe to (n1+k1)-th subframe CSI-RS is transmitted up to the subframe.

The base station may signal the CSI request to the terminal through a CSI request field of a DL downlink control information (DCI) format. Upon receiving the CSI request, the UE receives the (n1+k1)-th subframe (FIG. 1a), N consecutive DL subframes from the (n1+k1)-th DL subframe (FIG. 1B), or the (n1+k1)-th DL CSI-RS may be received in N consecutive DL subframes ( FIG. 1C ) up to the subframe, and CSI for aperiodic CSI reporting corresponding to the CSI request may be measured using this. Here, the UE may assume that the CSI-RS associated with the CSI request is transmitted in the corresponding DL subframe(s) only when there is a CSI request. If the UE assumes that the CSI-RS is transmitted only when there is a CSI request, the time interval (or time domain measurement window) for the corresponding CSI measurement is the DL subframe(s) in which the CSI-RS corresponding to the CSI request is transmitted. ) can be limited. For the CSI-RS transmission associated with the CSI request, the base station in the RRC signaling parameter of the CSI-RS configuration (CSI-RS configuration for Transmission mode 9) and/or the RRC signaling parameter of the CSI process configuration, CSI by CSI request - Whether to allow RS transmission can be included. For the NZP CSI-RS included in the CSI-RS configuration or CSI process configuration, a CSI-RS subframe configuration including a period and an offset may be configured to enable periodic transmission. However, the UE configured to allow the CSI-RS transmission associated with the CSI request does not always transmit the CSI-RS in the CSI-RS subframe, but when there is a CSI request (eg, in the n1 th subframe) N consecutive DL subframes from (n1+k1)th subframe (FIG. 1A), (n1+k1)th DL subframe (FIG. 1B), or (n1+k1)th DL subframe If the DL subframe (FIG. 1c) is a CSI-RS subframe, it is considered that the CSI-RS is transmitted, and a channel can be measured using this.

Method M221-1B is a method in which the base station transmits the CSI-RS according to the CSI-RS transmission request of the terminal. Specifically, when the base station receives the CSI-RS transmission request in the n2 th UL (uplink) subframe from the UE, it transmits the CSI request to the UE in the (n2 + k2) th DL subframe, and CSI according to method M221-1A -Send RS. Here, k2 is a value defined in advance as an integer greater than or equal to 0, may be defined as one value in frequency division duplexing (FDD), and defined as a different value according to UL/DL configuration in time division duplexing (TDD). can be The UE may transmit CSI-RS transmission request information to the base station through a physical uplink control channel (PUCCH) or a medium access control (MAC) control element (CE). For this, the existing PUCCH format or MAC CE format may be used or these may be newly defined. The UE may request the BS to transmit CSI-RS including CSI-RS APG information required for reception. The CSI-RS APG information is the CSI-RS APG ID of the CSI-RS APG or a plurality of CSI- It may include a CSI-RS APG ID list indicating RS APG IDs. In addition, the CSI-RS APG information is, when CSI-RS is configured using the above-described multiple CSI process, a CSI process ID of a CSI process corresponding to the CSI-RS APG or CSI referring to a plurality of CSI process IDs. It can include a list of process IDs. An example related to the CSI-RS transmission request of the UE is described in the following method M222.

Method M222 is a combination of methods M220 and M221. As an example of the combination of method M220 and method M221-1A, the base station periodically transmits CSI-RS, but requests CSI from the terminal for updating previously reported CSI or to receive additional CSI feedback, CSI-RS required for CSI measurement may be transmitted to the UE. As another example of the combination of the method M220 and the method M221-1A, the base station periodically transmits a CSI-RS corresponding to the horizontal domain for CSI reporting for the horizontal domain, but when the base station updates the CSI for the vertical domain When it is determined that it is necessary, CSI for the vertical domain may be requested from the UE, and accordingly, the CSI-RS corresponding to the vertical domain may be instantaneously transmitted.

For the combination of the method M220 and the method M221-1B, the method for the UE to trigger a CSI-RS transmission request includes: reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), and For any singular or plural combinations of CQI, each metric value is compared with the respective threshold value, the degree of change of each value is compared relative, or the degree of change of each value is compared with the threshold value. can do. For example, when the CSI-RS for the vertical domain is transmitted aperiodically and the CSI-RS for the horizontal domain is transmitted periodically, the UE obtains the vertical domain CSI condition from the most recently received vertical domain CSI-RS. , CSI for the joint domain in consideration of both the vertical and horizontal domains can be measured by using the CSI-RS for the horizontal domain. At this time, when the difference between the measured CQI and the previously reported CQI is equal to or greater than a certain level, the UE requests CSI-RS transmission for the vertical domain from the base station for CSI update for the vertical domain.

Meanwhile, method M222 may include the following methods (method M222-1A, method M222-1B) in order to prevent collision between periodic CSI-RS transmission and instantaneous CSI-RS transmission. Method M222-1A is a method in which the base station does not transmit an instantaneous CSI-RS in a CSI-RS subframe within a CSI-RS occasion of a periodic CSI-RS. Method M222-1B is a method for the base station to set the CSI-RS transmission resource of the instantaneous CSI-RS so that the CSI-RS transmission resource of the periodic CSI-RS does not overlap.

On the other hand, for CSI-RS transmission and configuration, any plurality of methods among the above-described methods may be combined.

3. CSI measurement and reporting, methods for setting them, and other related methods

A series of procedures for CSI measurement and reporting of the UE is as follows. The UE receives the CSI-RS according to the CSI-RS configuration of the base station, and estimates a channel from each CSI-RS AP therefrom. The UE measures CSI (including RI, PMI, or CQI) using the estimated channel, and transmits it through a PUCCH or a physical uplink shared channel (PUSCH) at the corresponding report time.

In CSI measurement and reporting for a two-dimensional antenna array, CSI reporting overhead may be significantly increased due to an increase in the number of antenna ports, so an efficient CSI reporting method is required in consideration of the antenna array configuration and corresponding channel characteristics. In addition, the method of CSI reporting may be different depending on the CSI-RS transmission method.

The CSI measurement method may include the following two methods (method M300 and method M301) according to whether spatial domains are distinguished. Method M300 is a method for the UE to measure CSI by dividing it into vertical domain CSI (hereinafter 'vCSI') and horizontal domain CSI (hereinafter 'hCSI'). Method M301 is a method in which the UE measures joint domain CSI (hereinafter 'jCSI') without distinction of spatial domains.

In method M300, vCSI may include a vertical domain PMI (hereinafter 'vPMI'), a vertical domain RI (hereinafter 'vRI'), and a vertical domain CQI ('vCQI'). vCSI on behalf of vPMI, VI, vertical domain beam Indicator (vertical domain beam Index, vertical domain beam ID, hereinafter 'beam indicator'), or NZP CSI-RS resource indicator (or NZP CSI-RS resource) corresponding to the beam indicator configuration ID). The UE obtains each item of vCSI using a channel estimated from vertical domain CSI-RS APs, or all, some, or one It can be obtained using the estimated channels of the CSI-RS APs corresponding to the column.

In the RI, in the case where measurement and reporting are fixed only for one rank (hereinafter, 'rank restriction'), vRI may be excluded from vCSI reporting.

In CQI, when only CQI considering both vCSI and hCSI is reported, vCQI may be excluded from vCSI reporting.

In hCSI, except that the UE uses the estimated channels of CSI-RS APs corresponding to all, some, or one row consisting of CSI-RS APs listed in the horizontal domain among all CSI-RS APs, except that , all of the above related to vCSI may be equally applied to hCSI.

The base station may receive vCSI and hCSI from the UE, respectively, and infer jCSI using them. The joint domain RI (hereinafter, 'jRI') may be defined as a product of vRI and hRI. The joint domain precoding matrix may be defined as a Kronecker product of a precoding matrix corresponding to vPMI and a precoding matrix corresponding to hPMI. The joint domain CQI (hereinafter 'jCQI') may be defined as the sum of vCQI and hCQI on a dB (or log) scale, or may be defined as a product of vCQI and hCQI on a linear scale.

In method M300, hCSI may be measured based on vCSI. Specifically, the UE may measure and report hCSI based on previously measured and/or reported vCSI. For example, when the terminal receives CSI-RSs for all antenna ports used by the base station for data transmission, hPMI may be determined based on vRI ^* and vPMI ^* that are predetermined (obtained) vRI and vPMI. For this purpose, for a given hRI and each candidate hPMI, the UE considers the Kronecker product of the two precoding matrices corresponding to hPMI and vPMI ^* as a joint precoding matrix, and uses it together with the channel estimated from the CSI-RS to determine the PMI selection metric (Metric) can be calculated and hPMI that meets the optimal criteria can be selected using the PMI selection metric.

In selecting the hRI, the UE may also calculate the RI selection metric by restricting vRI and vPMI based on the predetermined vRI ^* and vPMI ^* , and select an hRI that meets the optimal criteria. Let the hRI selected in this way be hRI ^* . Alternatively, the UE may obtain jRI using only the estimated channel (let the jRI thus obtained be jRI ^* ), and hRI may be obtained by dividing jRI ^* by vRI ^* . Let the hRI obtained in this way be hRI ^* .

Meanwhile, vRI ^* may be replaced with a previously constrained value without a decision. In this case, the hCQI of hCSI may be replaced with jCQI measured by considering all of vRI ^* , vPMI ^* , hRI ^* , and hPMI ^* instead of hCQI measured by considering only hRI ^* and hPMI ^* .

Meanwhile, in contrast to a method in which the UE measures hCSI based on vCSI, vCSI may be measured based on hCSI. In such a case, vCSI is measured by a method in which hCSI and vCSI are exchanged for each other in the above-described method. When the base station can configure one of the two methods (a method of measuring hCSI based on vCSI, a method of measuring vCSI based on hCSI) to the UE, the base station signals one of the two methods to the UE with higher-layer can be set through , and accordingly, the UE can perform CSI measurement. Alternatively, the base station may configure the UE to measure CSI of another domain based on which spatial domain through CSI-RS configuration and/or CSI reporting configuration.

The vPMI and hPMI are divided into wideband vPMI (wvPMI), subband vPMI (svPMI), wideband hPMI (whPMI), and subband hPMI (shPMI) according to a measurement resource unit, and may be measured for this purpose. wvPMI and whPMI mean PMI measured in consideration of CSI-RS of the entire band, and svPMI and shPMI mean PMI measured in consideration of CSI-RS of a corresponding subband obtained by dividing the entire band.

On the other hand, the base station can set the codebook subset restriction defined in the current standard to the terminal for each domain when the terminal obtains the vRI, vPMI, hRI, and hPMI, and the terminal receiving the set restriction for each domain The measured values are obtained after excluding the RI and PMI values.

In method M301, jCSI may include RI, PMI, and CQI obtained by the UE considering channels of antenna ports for two domains at the same time. In the current standard, the UE performs CSI measurement and reporting in the form of jCSI.

The UE measures CSI suitable for the CSI reporting mode configured for the vCSI, hCSI, and/or jCSI described above in the CSI reference resource. In the current standard, the CSI reference resource is defined to be located in the (n3- _{n CQI_ref} )-th DL subframe when the _UE transmits a CSI report in the n3-th UL subframe. _{n CQI_ref} for periodic _CSI reporting, which will be described later, is generally greater than or equal to 4 or 5 and is defined as the smallest value corresponding to a valid DL subframe. n _{CQI_ref} for aperiodic CSI reporting, which will be described later, is defined such that a CSI reference resource is located in a valid DL subframe in which the UE receives a CSI request in UL DCI format from the base station. This may be suitable only when all CSI-RS APs for CSI measurement are transmitted in one CSI-RS subframe. As described above, when CSI-RS APs are divided and transmitted in a plurality of CSI-RS subframes, _{n CQI_ref must} be defined so that all corresponding CSI-RS APs can be included in the CSI reference resource. A signal is transmitted from a CSI-RS AP belonging to a plurality of CSI-RS APGs in different CSI-RS subframes, and if different CSI-RS APGs have different periods and/or offsets, each CSI-RS APG n CQI _ ref for n _{CQI _ ref} may be defined as the smallest value that is greater than or equal to 4 or 5 and corresponds to a valid DL subframe in which each CSI-RS APG is transmitted. When the UE divides CSI into vCSI and hCSI for measurement, a CSI reference resource for measuring vCSI (hereinafter 'vCSI reference resource') and a CSI reference resource for measuring hCSI (hereinafter 'hCSI reference resource') for each n _{CQI _ ref} may be defined in consideration of a CSI-RS subframe in which CSI-RSs of corresponding CSI-RS APs are transmitted. That is, n _{CQI_ref} for _{the vCSI} reference resource is greater than or equal to 4 or 5, and is defined as the smallest value corresponding to the CSI-RS subframe in which the CSI-RS of CSI-RS APs used to measure vCSI are transmitted. can be And, n _{CQI_ref} for _{the hCSI} reference resource is greater than or equal to 4 or 5, and is defined as the smallest value corresponding to the CSI-RS subframe in which the CSI-RS of CSI-RS APs used to measure hCSI are transmitted. can be

Meanwhile, the CSI reporting method may include the following three methods (method M320, method M321, method M322) according to periodicity or instantaneousness. Method M320 is a method in which the UE periodically reports CSI. Method M321 is a method in which the UE performs aperiodic CSI reporting. Method M322 is a method in which the UE performs CSI reporting by correlating periodic CSI reporting and aperiodic CSI reporting.

In method M320, the UE transmits a PUCCH-based periodic CSI report to the base station. The UE transmits a CSI report through PUCCH when it does not receive a UL grant, and transmits a CSI report through PUSCH when it receives a UL grant. In order to vary the reporting period for each CSI item, the base station sets a parameter related to the period to the terminal. Meanwhile, for CSI reporting separated into vCSI and hCSI, a period for each CSI item may be set, and a CSI report type may be newly defined accordingly.

In method M321, the UE transmits a PUSCH-based aperiodic CSI report to the base station. The UE receives the CSI request through the CSI request field in the UL DCI format from the base station, and performs measurement and report accordingly. The base station may request a CSI report for some of the antenna ports of the antenna ports by using the CSI request field from the terminal. As described above, when the base station configures the CSI-RS using the CSI-RS occasion, the CSI-RS APG ID of the corresponding CSI-RS APG or a plurality of CSI-RS among the CSI-RS occasion configuration information. A CSI-RS APG set ID (set in advance through higher-layer signaling) indicating RS APG may be included in the CSI request. Or, when the base station sets the CSI-RS using multiple CSI processes, the CSI process ID of the CSI process corresponding to the CSI-RS APG or the CSI process set ID corresponding to a plurality of CSI-RS APGs (in advance higher- set through layer signaling) may be included in the CSI request. Meanwhile, the base station may request CSI for a desired spatial domain from the terminal using the CSI request field. In this case, the base station may need to transmit the CSI-RS so that the terminal can measure CSI for the corresponding spatial domain.

Method M322 is a combination of method M320 and method M321. The base station may configure the UE to periodically report CSI, and in connection with this, configure the UE to report CSI aperiodically. The base station may notify the UE of configuration information on the inter-correlation between the periodic CSI report and the aperiodic CSI report through higher-layer signaling. Method M322 will be described with reference to FIG. 2 . 2 exemplifies periodic CSI reporting and aperiodic CSI reporting having P subframes as a period.

As illustrated in FIG. 2 , the UE configured through higher-layer signaling that periodic CSI reporting and aperiodic CSI reporting are interrelated with each other uses CSI measurement for periodic CSI reporting as a reference (or condition). , CSI measurement for aperiodic CSI reporting may be performed. Alternatively, on the contrary, the UE may perform CSI measurement for periodic CSI reporting on the basis (or condition) of CSI measurement for aperiodic CSI reporting. When the UE performs aperiodic CSI reporting in the (n+2P+c)-th subframe, CSI is measured based on the CSI reported in the (n+2P+c)-th subframe as a reference (or condition), and measurement The CSI may be periodically reported to the base station from the (n+3P)-th subframe. Here, the criterion (or condition) may be valid only until the next aperiodic CSI report. Alternatively, when the UE periodically reports CSI up to the (n+2P)-th subframe, CSI is measured based on the periodically reported CSI (or condition), and the measured CSI is (n+2P+c) It can be reported aperiodically in the th subframe. As an example of this, the base station may configure the UE to report vCSI aperiodically, and configure the UE to periodically report hCSI measured based on the vCSI.

Meanwhile, the CSI reporting method may include the following two methods (method M320 and method M321) according to the configured number of CSI processes. Method M320 is a method for the UE to report by setting a single CSI process. Method M321 is a method of performing reporting by configuring multiple CSI processes.

Both method M320 and method M321 are supported in the current standard. Each of the method M320 and the method M321 may be considered differently according to a PUCCH-based periodic CSI report or a PUSCH-based aperiodic CSI report.

When the UE performs PUCCH-based periodic CSI reporting based on a single CSI process configuration, in order for the UE to report vCSI and hCSI separately, a new reporting period-related parameter must be defined according to the increased CSI items, The CSI report type must be newly defined according to the transmission combination of new CSI items.

When the UE performs PUSCH-based aperiodic CSI reporting based on a single CSI process configuration, the UE may simultaneously transmit CSI measured by method M300 or method M301.

When the UE performs PUCCH-based periodic CSI reporting based on multiple CSI process configuration, the UE divides vCSI and hCSI to report, as described above, the UE measures and reports vCSI and hCSI, respectively. Thus, a method of configuring a CSI process for each vCSI and hCSI may be included. In this case, the UE may reuse the PUCCH-based periodic CSI reporting method defined in the current standard as a reporting method for each CSI, and differentially set the vCSI reporting period and hCSI reporting period to A method of mitigating the overhead may also be used. However, as described above, the reference CSI process is defined such that the linkage information of the two CSI processes is included in the CSI process configuration or the CSI-RS configuration, or that the CSI of one CSI process becomes a reference for CSI measurement of the other CSI process. it is necessary to do For example, when the base station allows the terminal to measure hCSI based on vCSI, the vCSI-reference CSI process may be defined, and the corresponding CSI process ID may be informed to the terminal through higher-layer signaling. The UE may measure hCSI through a CSI process corresponding to hCSI based on vCSI measured (and/or reported) through the vCSI-reference CSI process. In this way, when the base station defines the vCSI-reference CSI process, it may be necessary to define the assumption of the terminal together with the configuration of the measurement subframe set. Here, the measurement subframe set means a set consisting of a single or a plurality of subframe(s) in which the UE can assume the same channel and/or interference when measuring CSI. A UE configured with a measurement subframe set through higher-layer signaling may measure CSI for each measurement subframe set.

If the vCSI-reference CSI process is defined only for a single measurement subframe set, the vCSI-reference CSI process is a reference for all of the plurality of measurement subframe sets when measuring hCSI for a plurality of measurement subframe sets. As such, the terminal may assume. That is, when the vCSI-reference CSI process is configured only for a single measurement subframe set and a CSI process corresponding to hCSI is configured for a plurality of measurement subframe sets, the UE according to the above assumption, the vCSI-reference CSI It is possible to measure hCSI for all measurement subframe sets based on the vCSI of the process.

If the vCSI-reference CSI process is defined for each measurement subframe set, the UE may assume that the vCSI-reference CSI process becomes a reference only when measuring hCSI of the corresponding measurement subframe set. That is, when a vCSI-reference CSI process is configured for a plurality of measurement subframe sets and a CSI process corresponding to hCSI is configured for the same measurement subframe sets, the UE according to the above assumption, each measurement subframe set hCSI for the corresponding measurement subframe set may be measured based on the vCSI for the frame set.

4. How to configure and set up the codebook

When the base station transmits a signal to the terminal, in order to form a beam or perform precoding on the signal, the base station uses a channel vector (or channel matrix, hereinafter referred to as a 'channel matrix') between the base station and the terminal or instead of it, or Channel state information that can be inferred must be acquired. To this end, when the base station transmits a reference signal (eg, NZP CSI-RS) to the terminal, the terminal estimates the channel using it.

In order for the terminal to report the estimated channel matrix or the corresponding precoding matrix itself to the base station, an infinite feedback size is required. In order for the UE to report a channel matrix or a precoding matrix corresponding thereto with a limited feedback size, a codebook composed of a finite number of channel matrices or precoding matrices is defined. Each channel matrix or precoding matrix included in the codebook has a unique Indicator (or Index). The base station and the terminal know the codebook in the same way in advance. The terminal can have the best performance (or selection index) when beamforming (or precoding) is performed using the channel matrix (or precoding matrix) included in the codebook for the estimated channel matrix. (or the precoding matrix) finds an indicator (this is defined as PMI), and reports it to the base station.

The base station forms a beam or performs precoding using a channel matrix (or precoding matrix) corresponding to the reported PMI. On the other hand, when the number of transmit antenna ports is large, a larger number of feedback sizes may be required to keep up with the corresponding increase in channel capacity.

Meanwhile, in order to reduce the PMI feedback size, the codebook may have a dual structure. In order for the UE to report one channel matrix (or precoding matrix) belonging to the codebook, the PMI may be divided into a first PMI and a second PMI. The first PMI may be defined to have a longer period or to be reported less frequently than the second PMI. The first PMI may refer to a set consisting of a plurality of channel matrices (or precoding matrices). The second PMI includes information for selecting a single or a plurality of channel matrices (or precoding matrices) from within a set consisting of a plurality of channel matrices (or precoding matrices) indicated by the first PMI, and/or It may be defined to include information for combining all or a plurality of selected channel matrices (or precoding matrices).

In addition, when the transmit antenna array consists of orthogonal antenna pairs having double polarization (that is, when a cross polarization antenna is used), the second PMI may be defined to include information for co-phasing different polarizations. . The plurality of channel matrices (or precoding matrices) referred to by the first PMI may be configured such that beams corresponding to respective columns of the matrix are adjacent to each other, or are not adjacent to each other and spaced apart by a predetermined interval. The former is suitable for use in a well-calibrated system, and the latter can be used in a poorly-calibrated system.

Accordingly, in order to increase performance, the plurality of channel matrices referred to by the first PMI may be configured differently according to the degree of antenna calibration of the base station. To this end, a codebook having a dual structure (hereinafter, 'dual codebook') is defined to have a plurality of first PMI configurations, and the base station provides configuration information (or an indicator indicating configuration information) of the first PMI to be used to the terminal. It is notified through higher-layer signaling (or system information block (SIB) signaling, RRC signaling). The terminal selects and reports the PMI based on the configuration information of the configured first PMI. Hereinafter, the configuration of the first PMI is referred to as a first PMI configuration. Here, defining the codebook to have a plurality of first PMI configurations is not limited to the purpose of adaptive to antenna calibration performance, and may be used for other purposes as well. As an example of a method of setting the configuration of the first PMI adaptively to the antenna calibration performance, the configuration of four adjacent beams and the configuration of four beams shifted by 90 degrees each include the first PMI configuration of the dual codebook. In the case where the antenna calibration satisfies a certain level, the base station sets the first PMI configuration consisting of four beams adjacent to the terminal, and the base station whose antenna calibration does not satisfy the certain level is four pieces that are twisted by 90 degrees to the terminal. A first PMI configuration composed of beams may be configured.

Meanwhile, in order to alleviate interference due to the use of a specific PMI or to restrict selection of a specific rank, a subset of the codebook may be constrained. Here, the subset constraint of the codebook is that, with respect to some of the channel matrices (or precoding matrices) included in the codebook, a constraint is applied so that the terminal does not select the part and/or does not report on the part it means. For example, when the codebook size is 16 (eg, it is assumed that the indicator range in the codebook is 0-15) and the codebook subset is not constrained, the UE may select and report the PMI from 0-15. For another example, when the codebook subset is restricted so that indicators of 0 to 7 are not selected, the terminal may select and report PMIs in 8-15. In the existing codebook subset constraint method, the base station defines whether the selection of each indicator in the codebook is constrained by a bitmap (e.g., bit 0 is defined as a constraint, bit 1 is allowed as a constraint, or conversely, bit 1 is defined as a constraint Bit 0 is defined as allow), and this is set to the terminal through higher-layer signaling. Also, even if the codebook subset is constrained, the UE may report the PMI with the same feedback size.

Meanwhile, in order to quickly signal the codebook subset constraint, physical layer signaling such as DCI may be used. Since physical layer signaling has limited signaling resources, it may be impossible or inefficient to signal whether selection of each indicator in the codebook is restricted through a bitmap. In addition, in a method of setting codebook subset constraint using higher-layer signaling (or SIB signaling, RRC signaling), it is necessary to reduce signaling overhead for codebook subset constraint of a large codebook.

As a method for solving this problem, there is a method of grouping a plurality of indicators (or PMIs) and configuring the selection restriction in a group unit as a bitmap (hereinafter, 'first signaling overhead mitigation method'). For example, if the codebook size is 16, if the indicators of 0~3 are group 0, the indicators of 4~7 are group 1, the indicators of 8~11 are group 2, and the indicators of 12~15 are When group 3 is configured, the codebook subset constraint consists of a bitmap of 4 bits. As a specific example of this, when the base station configures the codebook subset constraint information of '0110' (eg, bit 0 is defined as allowing bit 1 as a constraint), the terminal determines the number of indicators belonging to groups 0 and 3 It is interpreted that selection is limited.

In addition, as another method of relaxing the signaling size for the codebook subset constraint, there is a method using a double codebook structure (hereinafter, 'second signaling overhead mitigation method'). The bitmap for codebook subset constraint may be configured in units of the first PMI. Selection of all channel matrices (or precoding matrices) referred to by the constrained first PMI (or a corresponding pair of the first PMI and the second PMI) may be restricted. For example, when the size of the double codebook is 8 bits, the first PMI consists of 4 bits, and the second PMI consists of 4 bits, the bitmap size is 256 bits in the existing codebook subset constraint method, whereas the first If the codebook subset constraint is performed in units of PMI, the bitmap size consists of 16 bits.

In addition, as another method of relaxing the signaling size for constraining the codebook subset, there is a method of restricting the first PMI by grouping a plurality of groups with respect to a double codebook (hereinafter, 'third signaling overhead mitigation method'). The third signaling overhead mitigation method is a method in which the above-described first and second signaling overhead mitigation methods are combined. In this case, selection of all channel matrices (or precoding matrices) (or the corresponding pair of the first PMI and the second PMI) referred to by all the first PMIs in the constrained group is restricted.

As a method of expressing the codebook subset constraint, in addition to the method of expressing the codebook subset constraint as a bitmap, there may be a method of grouping a plurality of indicators and indicating a group indicator to be constrained. All indicators belonging to the indicated group indicator are constrained in selection.

In the above-described bitmap representation-based codebook subset constraint, the bitmap may include all constraints for each rank, or the bitmap may be configured in common for all ranks. In order for the latter case to be used, the first PMI may have to be equally defined for all ranks.

On the other hand, the constraints in all the codebook subset constraint methods described above may be replaced with allow. In this case, everything is the same as described above, except to interpret the meaning of the above restrictions as permissive.

Meanwhile, according to the existing method, even if the codebook subset is restricted, the UE may report the PMI to the base station with the same feedback size. In order to reduce the feedback size, the UE may sequentially assign new indicators to the remaining indicators except for the constrained indicator, and perform PMI reporting on the new indicators. Specifically, the terminal may assign indicators again from 0 to 'the number of unconstrained indicators - 1' in the order of the original indicators for the remaining indicators except for the constrained indicators. For example, when indicators of 0, 1, 5, 10, 12, 13, 14, and 15 are constrained in a codebook having indicators of 0 to 15, the terminal uses Table 1 below for unconstrained indicators and Set a new indicator together.

Example of codebook indicator change according to codebook restrictions original indicator 2 3 4 6 7 8 9 11 New indicator according to codebook constraints 0 One 2 3 4 5 6 7

The terminal reports the newly assigned indicator to the base station for the remaining indicators except for the restricted indicator. In this case, the size of the PMI is 3 bits, which is the size of the restricted codebook, not 4 bits. Since the base station is the organizer of the codebook subset constraint, it knows that the PMI is reported as 3 bits according to the codebook subset constraint, and based on the reported PMI, the unrestricted indicator can be interpreted as shown in Table 1 above. For example, when the terminal reports PMI 3 to the base station, the base station converts the reported PMI 3 into the original indicator 6, and obtains a channel matrix (or precoding matrix) corresponding to the indicator 6.

5. How to set up the CSI process

According to the above-described TXRU virtualization and antenna port virtualization, a beam shape of a signal transmitted through an antenna port may be different. The beam shape can be characterized by the width of the beam and the direction of the beam. Accordingly, in CSI-RS AP transmission, the width and direction of the CSI-RS AP beam may be different due to the two virtualizations. Hereinafter, a first CSI-RS mode is defined to transmit a signal of a CSI-RS AP so that the beam width is as wide as the cell coverage and different CSI-RS APs have the same beam width and beam direction. In addition, a second CSI-RS mode is defined to transmit a signal of the CSI-RS AP so that the beam width is smaller than the cell coverage and different combinations of CSI-RS AP and CSI-RS resource have different beam directions.

In the second CSI-RS mode, unlike in the first CSI-RS mode, the UE selects all or some of the beams applied to the CSI-RS APs when measuring CSI, and the CSI (eg, CQI, PMI, RI) any combination of these) is measured and reported. Therefore, the first CSI-RS mode and the second CSI-RS mode may be divided into a beam form of a CSI-RS AP signal, or a single or a plurality of beams are selected during CSI measurement and reporting, and related information is reported. It may be classified according to whether or not it includes.

The terms for the first CSI-RS mode and the second CSI-RS mode may be replaced with CSI reporting class A and CSI reporting class B, respectively. Hereinafter, unless otherwise specified, the terms first CSI-RS mode and second CSI-RS mode are used. The base station may operate the first CSI-RS mode, the second CSI-RS mode, or a combination of both. In addition, the base station may operate different modes for each terminal.

5.1. first CSI- RS mode

Conventionally, one CSI process is associated with one CSI-RS resource (or NZP CSI-RS resource) and one CSI-IM resource. The CSI reported by the UE corresponds to a CSI process configured through higher-layer signaling. Existing NZP CSI-RS resources may configure 1, 2, 4, or 8 CSI-RS APs.

On the other hand, in the first CSI-RS mode, support of NZP CSI-RS having more than 8 antenna ports such as 12 or 16 is required. The method of configuring the NZP CSI-RS having the number of antenna ports exceeding 8 may include a method of configuring a plurality of NZP CSI-RS resources having a 3GPP LTE Release 12 definition or a new definition. For example, NZP CSI-RS having 12 antenna ports may be configured as a combination of NZP CSI-RS resources having 8 antenna ports and NZP CSI-RS resources having 4 antenna ports, or 4 antennas It can be configured as a combination of three NZP CSI-RS resources having a port. If all NZP CSI-RS resources are constrained to have the same number of antenna ports, the latter configuration may be used.

In order to configure a plurality of NZP CSI-RS resources, one CSI process may be associated with a plurality of NZP CSI-RS resources and one CSI-IM resource, unlike the existing one. Specifically, so that a plurality of NZP CSI-RS resource configurations and CSI-IM resource configurations are included in one CSI process configuration, the base station includes an ID list indicating a plurality of NZP CSI-RS resource configurations and a CSI-IM resource configuration. ID (CSI-IM resource configuration ID) may be included in the CSI process configuration. That is, the base station includes the NZP CSI-RS resource configuration ID list in the CSI process configuration instead of the existing NZP CSI-RS resource configuration ID. The NZP CSI-RS resource configuration ID list includes single or multiple NZP CSI-RS resource configuration IDs. The UE having the CSI process configuration configured through higher-layer signaling measures the channel using the CSI-RS of the CSI-RS APs included in the NZP CSI-RS resources corresponding to the NZP CSI-RS resource configuration ID list, Interference is measured in a resource defined for CSI-RS APs included in the CSI-IM resource corresponding to the CSI-IM resource configuration ID, and CSI is measured therefrom, and this is reported to the base station. For this, the UE may assign port numbers to the following two methods (method M410 and method M420) for CSI-RS APs defined in a plurality of NZP CSI-RS resources.

Method M410 is a method in which the UE assigns CSI-RS AP numbers in the order they are input to the NZP CSI-RS resource configuration ID list (hereinafter, 'first list'). For example, ID values in the NZP CSI-RS resource configuration ID list indicating two NZP CSI-RS resource configurations are set to 1 and 0, and the NZP CSI-RS resource configuration ID given as the first in the first list When the NZP CSI-RS resource corresponding to 1 has 8 ports, and the NZP CSI-RS resource corresponding to the next NZP CSI-RS resource configuration ID 0 has 4 ports, the terminal is the NZP CSI-RS Port numbers of 15 to 22 are assigned to 8 ports corresponding to resource configuration ID 1, and 23 to 26 following the previous port number assignment to 4 ports corresponding to NZP CSI-RS resource configuration ID 0 Specifies the port number of

Method M420 is a method for the UE to number CSI-RS APs in ascending order (or descending order) of NZP CSI-RS resource configuration IDs in the first list. For example, assuming that the UE numbers CSI-RS AP numbers in ascending order of NZP CSI-RS resource configuration IDs, ID values in the NZP CSI-RS resource configuration ID list indicating two NZP CSI-RS resource configurations are 1, 0, the NZP CSI-RS resource corresponding to the NZP CSI-RS resource configuration ID 0 has 4 ports, and the NZP CSI-RS resource corresponding to the NZP CSI-RS resource configuration ID 1 has 8 ports. In the case of having a port, the terminal assigns port numbers 15 to 18 to 4 ports corresponding to NZP CSI-RS resource configuration ID 0, and 8 ports corresponding to NZP CSI-RS resource configuration ID 1 For port number 19~26 following the previous port number assignment.

5.2. 2nd CSI- RS mode

Meanwhile, in the second CSI-RS mode, beams may be formed and transmitted in different directions for the NZP CSI-RS AP, the NZP CSI-RS resource, or a combination thereof. Hereinafter, a resource unit including a single or a plurality of NZP CSI-RS AP(s) to which the same beam is applied is collectively referred to as a BF CSI-RS resource.

5.2.1. 2nd CSI- RS mode CSI- RS How to set up

In the CSI-RS configuration method for the second CSI-RS mode, for CSI measurement for a single or a plurality of beams, the UE transmits a single or a plurality of NZP CSI-RS resources in one CSI process through higher-layer signaling. get set up In this case, the UE may assume that beamforming is applied in the same direction to the CSI-RSs of all CSI-RS APs within the same NZP CSI-RS resource. In addition, the UE may assume that different beamforming is applied between CSI-RSs transmitted in different NZP CSI-RS resources. Accordingly, one NZP CSI-RS resource corresponds to one BF CSI-RS resource. To this end, the base station may include the NZP CSI-RS resource configuration ID list in the CSI process configuration so that a plurality of NZP CSI-RS resource configurations are included in the CSI process configuration. Here, the number of NZP CSI-RS APs belonging to different NZP CSI-RS resources may be set to be the same. You may not expect to have an RS AP.

When the NZP CSI-RS resources have a different number of NZP CSI-RS APs, the CSI reporting/feedback payload size is different depending on the beam (or NZP CSI-RS resource) selected during CSI reporting. It can be difficult to assume this same CSI reporting/feedback payload size.

Additionally, in one CSI process configured through higher-layer signaling, the UE receives one CSI-IM resource commonly configured for all configured NZP CSI-RS resources, or different CSI for each configured NZP CSI-RS resource. -IM resource can be set. In the former case, one CSI process may be defined as one or more NZP CSI-RS resources and one CSI-IM resource are associated, and the UE may measure CSI by reflecting the same intra-cell interference There is this. In the latter case, one CSI process may be defined as one or more NZP CSI-RS resources and one or more CSI-IM resources are associated, and the UE uses NZP CSI-RS resources and CSI-IM resources corresponding to each beam. For each pair, there is a feature that can measure CSI by reflecting different intra-cell interference and/or different inter-cell interference. If one CSI-IM resource is configured in the CSI process, the UE follows the former, and when CSI-IM resources equal to the number of NZP CSI-RS resources are configured, the UE follows the latter.

It may not be expected that the UE is configured with a number of CSI-IM resources different from the number of NZP CSI-RS resources. In order to configure a plurality of CSI-IM resources, a plurality of CSI-IM resource configuration ID lists may be included in the CSI process configuration. The NZP CSI-RS resource and the CSI-IM resource form a pair with those belonging to the same order in the list to which each belongs, and the UE uses the CSI-RS of the CSI-RS APs belonging to the NZP CSI-RS resource in the pair. A channel is measured, interference is measured in a resource defined for CSI-RS APs belonging to a CSI-IM resource, and CSI is obtained from these (measured channel and measured interference). As described above, the UE measures a channel for CSI-RS APs of an NZP CSI-RS resource corresponding to each beam, and a common CSI-IM resource (or a corresponding beam (or a corresponding NZP CSI-RS resource) corresponding to the corresponding NZP CSI-RS resource). CSI-IM resource) selects a single or a plurality of beam(s) by measuring interference, measures CSI for the selected beam(s), and reports it. Here, the UE may include the NZP CSI-RS resource configuration ID(s) corresponding to the selected beam(s) in the CSI report by itself or by expressing it as a bitmap. When the terminal selects a single beam, the former may be advantageous, and when selecting a plurality of beams, the latter may be advantageous. The bitmap size may be defined as the maximum number of NZP CSI-RS resources that can be configured (included) by one CSI process or the number of NZP CSI-RS resources configured by one CSI process. The first bit from the left (or right) of the bitmap corresponds to the lowest (or highest) NZP CSI-RS resource configuration ID, and the next second bit is the second lowest (or highest) NZP CSI-RS resource configuration ID. , and the remaining bits may be defined to correspond to the ascending order (or descending order) of the NZP CSI-RS resource configuration ID. A bit having a value of 0 in the bitmap means that the NZP CSI-RS resource (or a beam corresponding to it) is not selected, and a bit having a value of 1 means that the NZP CSI-RS resource (or a beam corresponding to it) is not selected. It may be defined to mean selected, or it may be defined to have the opposite meaning.

When the large-scale property of a channel through which a symbol of one antenna port of a channel is transmitted can be inferred from a channel of a symbol through which another antenna port is transmitted, it is defined that the two antenna ports are quasi co-located. Here, the large-scale channel property may include one or a plurality of combinations of Doppler shift, Doppler spread, average delay, delay spread, and average gain.

In a UE in which transmission mode 8 to 10 is configured for a serving cell, DM-RS APs 7 to 14 of the serving cell in a given subframe are QCL (quasi co) for Doppler shift, Doppler spread, average delay, delay spread, and average gain -location) is satisfied. The UE may assume QCL for delay spread, Doppler spread, Doppler shift, average gain, and average delay between CSI-RS APs belonging to one CSI-RS resource configuration.

For the UE in which transmission mode 1 to 9 is configured for the serving cell, CRS APs 0 to 3, DM-RS AP 5, DM-RS APs 7 to 14, and CSI-RS APs 15 to 22 are Doppler shift, Doppler spread, average delay. It can be assumed that QCL is satisfied for , , and delay spread.

In decoding the PDSCH demodulated using DM-RS, the terminal set in transmission mode 10 for the serving cell, the following two types of QCLs (QCL Type A, QCL Type B) by the higher-layer parameter qcl-Operation define.

First, for QCL Type A, the UE obtains QCL for Doppler shift, Doppler spread, average delay, and delay spread between CRS APs 0 to 3, DM-RS APs 7 to 14, and CSI-RS APs 15 to 22. can be assumed In order to support the extended number of antenna ports for the first CSI-RS mode, the CSI-RS APs 15 to 22 may be replaced with CSI-RS APs 15 to (K+14). Here, K is the maximum number of configurable CSI-RS APs for one CSI process.

Next, for QCL Type B, the UE, CSI-RS APs 15 to 22 corresponding to the CSI-RS resource configuration identified by the higher-layer parameter qcl-CSI-RS-ConfigNZPId-r11, and the corresponding qcl-CSI - Between DM-RS APs 7 to 14 within the resource in which the PDSCH scheduled (or allocated) by the DL DCI format including the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field corresponding to RS-ConfigNZPId-r11 is transmitted QCL for Doppler shift, Doppler spread, average delay, and delay spread may be assumed. In order to support the extended number of antenna ports for the first CSI-RS mode, the CSI-RS APs 15 to 22 may be replaced with CSI-RS APs 15 to (K+14). Here, K is the maximum number of configurable CSI-RS APs for one CSI process.

Transmission mode 10 and QCL Type B configured terminal is between CRS APs 0~3 corresponding to qcl-CRS-Info-r11 of one CSI-RS resource configuration and CSI-RS APs 15~22 of the CSI-RS resource configuration. QCL for Doppler shift and Doppler spread may be assumed. In order to support the extended number of antenna ports for the first CSI-RS mode, the CSI-RS APs 15 to 22 may be replaced with CSI-RS APs 15 to (K+14). Here, K is the maximum number of configurable CSI-RS APs for one CSI process.

As described above, when the BF CSI-RS resource is divided for each NZP CSI-RS resource in the second CSI-RS mode, the UE uses all large-scale channels between CSI-RS APs belonging to different NZP CSI-RS resources. QCL for properties cannot be assumed, only QCL for Doppler shift and Doppler spread can be assumed, or only QCL for Doppler shift, Doppler spread, average delay, and delay spread can be assumed, or Doppler shift, Doppler spread , QCL for average delay, delay spread, and average gain can be assumed. Among these four QCL assumptions, one QCL assumption that the UE can follow may be defined in advance. Alternatively, the base station sets the QCL assumption for the large-scale channel attribute between CSI-RS APs belonging to different NZP CSI-RS resources through higher-layer signaling to the UE (for example, one of the above four assumptions can be set) and the UE may follow the corresponding assumption set through higher-layer signaling.

Transmission mode 1 to 9, or a terminal in which Transmission mode 10 is set together with QCL Type A, QCL between DM-RS antenna ports (except DM-RS AP 5 in the case of Transmission mode 10) and CSI-RS antenna ports You may need to make changes to your assumptions. The UE uses DM-RS antenna ports and the most recently reported (or most recently reported before k3 subframe based on the current subframe) NZP CSI-RS resource indicator ( QCL for Doppler shift, Doppler spread, average delay, and delay spread between CSI-RS antenna ports of NZP CSI-RS resource(s) indicated by '(or NZP CSI-RS resource configuration ID(s))' It can be assumed that this is satisfied. Here, k3≥K3, and K3 may be set to a value greater than or equal to 0 in consideration of the period between the reporting time of the corresponding information and the reception of the DL allocation information using the same. Whether the assumption holds is defined in advance, or the base station sets whether the assumption holds or not through higher-layer signaling to the terminal, and the terminal may follow it.

The UE, DM-RS antenna ports, and the most recently reported (or most recently reported before k3 subframe based on the current subframe) NZP CSI-RS resource indicator corresponding to the 'selected beam(s) QCL for all large-scale channel attributes between CSI-RS antenna ports of NZP CSI-RS resource(s) not referred to by (s) (or NZP CSI-RS resource configuration ID(s)) can be assumed Otherwise, only QCL for Doppler shift and Doppler spread may be assumed, or only QCL for Doppler shift, Doppler spread, average delay, and delay spread may be assumed. Here, k3≥K3, and K3 may be set to a value greater than or equal to 0 in consideration of the period between the reporting time of the corresponding information and the reception of the DL allocation information using the same. Among these three (or only some of the three candidates) QCL assumptions, one QCL assumption that the terminal can follow may be defined in advance, and the base station sends these three ( Alternatively, one of the QCL assumptions (with only some of the three candidates) may be set. In this case, the UE may follow the configured QCL assumption.

The terminal in which Transmission mode 10 is set together with QCL Type B, CSI-RS APs 15 to 22 corresponding to the CSI-RS resource configuration identified by the higher-layer parameter qcl-CSI-RS-ConfigNZPId-r11, and the corresponding qcl -DM-RS APs within the resource in which the PDSCH scheduled (or allocated) by the DL DCI format including the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field corresponding to -CSI-RS-ConfigNZPId-r11 is transmitted 7~ We assume QCL for Doppler shift, Doppler spread, average delay, and delay spread between 14. In this case, a method for supporting the case where the maximum number of configurable NZP CSI-RS resource configurations exceeds the existing limit of 3 is needed.

The first supported method is to extend the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field size and the range of PDSCH-RE-MappingQCL-ConfigId to the maximum number of configurable NZP CSI-RS resource configurations.

The second support method maintains the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field size (the existing size is 2 bits) and the range of PDSCH-RE-MappingQCL-ConfigId (the existing range is 1 to 4), and the PDSCH- This is a method of including the CSI process ID to which the NZP CSI-RS resource corresponding to qcl-CSI-RS-ConfigNZPId-r11 belongs instead of qcl-CSI-RS-ConfigNZPId-r11 of the RE-MappingQCL-Config parameter.

In this case, the UE includes CSI-RS APs 15 to 22 corresponding to the CSI-RS resource configuration(s) identified by the CSI process ID instead of the qcl-CSI-RS-ConfigNZPId-r11, which is a higher-layer parameter, and, DM-RS APs within the resource in which the PDSCH scheduled (or allocated) by the DL DCI format including the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field corresponding to the corresponding qcl-CSI-RS-ConfigNZPId-r11 is transmitted QCL for all large-scale channel properties between 7 and 14 cannot be assumed, QCL for Doppler shift and Doppler spread can be assumed, or QCL for Doppler shift, Doppler spread, average delay, and delay spread is assumed can do. Among these three QCL assumptions, one QCL assumption that the terminal can follow may be defined in advance, and the base station sends these three (or only some of the three as candidates) QCL through higher-layer signaling to the terminal. You can also set up one of the assumptions. In this case, the UE may follow the configured QCL assumption.

Alternatively, the UE includes CSI-RS APs 15 to 22 corresponding to CSI-RS resource configuration(s) identified by CSI process ID instead of qcl-CSI-RS-ConfigNZPId-r11, which is a higher-layer parameter, and the corresponding qcl- DM within the resource in which the PDSCH scheduled (or allocated) by the DL DCI format including the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field corresponding to the CSI process ID instead of CSI-RS-ConfigNZPId-r11 is transmitted -RS APs 7 to 14 cannot assume QCL for all large-scale channel properties, or assume QCL for Doppler shift and Doppler spread, or for Doppler shift, Doppler spread, average delay, and delay spread QCL can be assumed. Among these three QCL assumptions, one QCL assumption that the terminal can follow may be defined in advance, and the base station sends these three (or only some of the three as candidates) QCL through higher-layer signaling to the terminal. You can also set up one of the assumptions. In this case, the UE may follow the configured QCL assumption.

Alternatively, the UE is the most recently reported (or the most recent subframe before k3 subframe based on the current subframe) for the CSI process identified by the CSI process ID instead of the higher-layer parameter qcl-CSI-RS-ConfigNZPId-r11. CSI of the NZP CSI-RS resource(s) indicated by the recently reported) 'NZP CSI-RS resource indicator(s) (or NZP CSI-RS resource configuration ID(s)) corresponding to the selected beam(s)' -RS antenna ports CSI-RS APs 15 to 22 and the PDSCH scheduled (or allocated) by the DL DCI format including the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field corresponding to the CSI process ID. It is not possible to assume QCL for all large-scale channel properties between DM-RS APs 7 to 14 in the transmitted resource, or QCL for Doppler shift and Doppler spread can be assumed, Doppler shift, Doppler spread, average delay, and QCL for delay spread may be assumed. Here, k3≥K3, and K3 may be set to a value greater than or equal to 0 in consideration of the period between the reporting time of the corresponding information and the reception of the DL allocation information using the same. Among these three QCL assumptions, one QCL assumption that the terminal can follow may be defined in advance, and the base station sends these three (or only some of the three as candidates) QCL through higher-layer signaling to the terminal. You can also set up one of the assumptions. In this case, the UE may follow the configured QCL assumption.

Alternatively, the base station groups NZP CSI resource(s) in which a QCL between CSI-RS antenna ports belonging to one or more NZP CSI resource(s) can be assumed, and an ID (NZP CSI resource group ID or NZP CSI resource configuration) in the group. group ID; the range may be 1 to 4), and this may be notified to the terminal through higher-layer signaling. This method is a method of using the NZP CSI resource group ID instead of the CSI process ID in the method using the CSI process ID described above.

Or, the UE corresponds to the qcl-CRS-Info-r11 parameter included in the CSI-RS resource configuration(s) identified by the higher-layer parameter qcl-CSI-RS-ConfigNZPId-r11 CRS APs 0 to 3 and, DM-RS APs within the resource in which the PDSCH scheduled (or allocated) by the DL DCI format including the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field corresponding to the corresponding qcl-CSI-RS-ConfigNZPId-r11 is transmitted QCL for all large-scale channel properties between 7 and 14 cannot be assumed, QCL for Doppler shift and Doppler spread can be assumed, or QCL for Doppler shift, Doppler spread, average delay, and delay spread is assumed can do. Among these three QCL assumptions, one QCL assumption that the terminal can follow may be defined in advance, and the base station sends these three (or only some of the three as candidates) QCL assumptions through higher-layer signaling to the terminal. You can also set one of them. In this case, the UE may follow the configured QCL assumption.

In the case where the CSI process configured through higher-layer signaling includes a plurality of NZP CSI-RS resources corresponding to each beam, the UE PMI for each NZP CSI-RS resource or for each selected at least one NZP CSI-RS resource. and RI, or common PMI and RI for all NZP CSI-RS resources or for at least one selected NZP CSI-RS resource. In addition, the UE may obtain CQI by using PMI(s) and RI(s) obtained for all NZP CSI-RS resource(s) or selected NZP CSI-RS resource(s). Here, PMI and CQI are values obtained based on wideband or subband. The terminal reports the obtained CQI, PMI, and RI to the base station.

5.2.2. 2nd CSI- RS mode CSI- RS Another way of setting

Another method of configuring the CSI-RS for the second CSI-RS mode, the UE receives a single or a plurality of NZP CSI-RS resources configured through higher-layer signaling in one CSI process, where one NZP CSI-RS resource This is a method including a plurality of BF CSI-RS resources. That is, one NZP CSI-RS resource may include CSI-RS APs to which a plurality of different beams are applied. Here, a set of NZP CSI-RS AP(s) to which the same beam is applied is defined as an NZP CSI-RS AP group. To this end, the CSI process configuration may include a plurality of NZP CSI-RS resource configuration ID lists. In addition, additional information is required to configure a plurality of NZP CSI-RS AP groups within one NZP CSI-RS resource, and the additional information includes the number of NZP CSI-RS APs in the NZP CSI-RS AP group, or It may include the number of RS AP groups. As described above, in order to avoid ambiguity about the CSI reporting/feedback payload size between the base station and the terminal, the number of NZP CSI-RS APs belonging to different BF CSI-RS resources (or NZP CSI-RS AP group) may be set identically. In addition, the total number of NZP CSI-RS APs in the NZP CSI-RS resource is a multiple of the number of NZP CSI-RS APs belonging to one BF CSI-RS resource (or the number of NZP CSI-RS APs in each NZP CSI-RS resource is BF It is set to be a multiple of the number of NZP CSI-RS APs belonging to the CSI-RS resource), or only configuration parameters that satisfy these conditions may be defined. Different IDs are given to all NZP CSI-RS AP groups spanning all NZP CSI-RS resources configured in one CSI process. Additionally, the UE receives one CSI-IM resource commonly configured for all configured NZP CSI-RS resources in one CSI process configured through higher-layer signaling, or different for each configured NZP CSI-RS resource. CSI-IM resources can be configured. In the former case, there is a feature that the UE can measure CSI by reflecting the same intra-cell interference. In the latter case, there is a feature that the UE can measure CSI by reflecting different intra-cell interference and/or different inter-cell interference. If one CSI-IM resource is configured in the CSI process, the UE follows the former, and when CSI-IM resources equal to the number of NZP CSI-RS resources are configured, the UE follows the latter. It may not be expected that the UE is configured with a number of CSI-IM resources different from the number of NZP CSI-RS resources. In order to configure a plurality of CSI-IM resources, the CSI process configuration may include a plurality of CSI-IM resource configuration ID lists. The NZP CSI-RS resource and the CSI-IM resource are paired with each other in the same order in the list to which they belong, and the UE is a CSI- A channel is measured using the CSI-RS of RS APs, interference is measured in a resource defined for CSI-RS APs belonging to a CSI-IM resource, and CSI is obtained from the measured channel and interference.

As described above, when the BF CSI-RS resources are divided for each CSI-RS AP group, the UE may need to change the QCL assumption between antenna ports. Previously, the UE could assume QCL for delay spread, Doppler spread, Doppler shift, average gain, and average delay between all CSI-RS APs included in the same CSI-RS resource configuration, but one CSI-RS resource When the CSI-RS APs in the configuration are transmitted on different beams, the existing QCL assumption may not be preferable. Therefore, even if the CSI-RS APs belong to the same NZP CSI-RS resource, the UE is responsible for delay spread, Doppler spread, Doppler shift, average gain, and average delay only between CSI-RS APs belonging to the same CSI-RS AP group. QCL can be assumed.

Additionally, when the PDSCH is transmitted in transmission mode 10, the NZP CSI-RS AP group is configured using qcl-CSI-RS-ConfigNZPId-r11 in the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field included in the corresponding DL DCI format. Since it is impossible to refer, qcl-CSI-RS-ConfigNZPId-r11 should be replaced with the NZP CSI-RS AP group ID corresponding to the beam through which the corresponding PDSCH is transmitted. When the number of beams (or the number of NZP CSI-RS AP groups) is larger than the previously configurable size of qcl-CSI-RS-ConfigNZPId-r11, the size of the field may be increased. The maximum number of NZP CSI-RS AP groups is defined, and each CSI process sets a smaller or equal number of NZP CSI-RS AP groups. Since the base station and the terminal know the maximum number of NZP CSI-RS AP groups, the 'PDSCH RE Mapping and Quasi-Co-Location Indicator' field size is set and assumed accordingly, and the base station and the terminal each receive DCI including the corresponding field. transmit and receive

In the case where the CSI process configured through higher-layer signaling includes a plurality of NZP CSI-RS AP groups corresponding to each beam, the UE is configured for each NZP CSI-RS AP group or at least one selected NZP CSI-RS AP. PMI and RI may be obtained for each group, or a common PMI and RI may be obtained for all NZP CSI-RS AP groups or for at least one selected NZP CSI-RS AP group. In addition, the UE may obtain a CQI by using the PMI(s) and RI(s) obtained for all NZP CSI-RS AP group(s) or the selected NZP CSI-RS AP group(s). Here, PMI and CQI are values obtained based on wideband or subband. The terminal reports the obtained CQI, PMI, and RI to the base station.

Meanwhile, a plurality of NZP CSI-RS resources may be configured in one CSI process in the first CSI-RS mode and the second CSI-RS mode. It is difficult for the UE to distinguish the first CSI-RS mode from the second CSI-RS mode only by receiving the CSI-RS AP according to the configured NZP CSI-RS resource. Meanwhile, in the first CSI-RS mode, the UE performs CSI measurement by the number of all CSI-RS APs configured over a plurality of NZP CSI-RS resources, whereas in the second CSI-RS mode, the UE performs each NZP CSI - Measure CSI for RS resources or for at least one selected NZP CSI-RS resource. Therefore, in order for the UE to perform CSI measurement and reporting in the CSI-RS mode intended by the base station, it is necessary to signal to the UE which CSI-RS mode (or CSI reporting class) CSI measurement and reporting is required for in the CSI process. there is For this purpose or other purposes, the CSI process configuration may include CSI-RS mode (or CSI reporting class) configuration information. The base station includes the CSI-RS mode (or CSI reporting Class) configuration information in the CSI process configuration configured to the terminal through higher-layer signaling, and the terminal receiving the configuration information for the corresponding CSI-RS mode (or CSI reporting class) Perform CSI measurement and reporting.

6. Measurement restriction method

When measuring CSI, the UE measures the channel experienced when a physical channel (or signal) targeting itself from the serving cell (or base station) is transmitted, and interference from other cells (or base stations) and/or the serving cell ( Alternatively, interference due to a physical channel (or signal) that does not target itself as a reception target is measured from the base station. Hereinafter, the former is referred to as a channel measurement, and the latter is referred to as an interferometric measurement.

Meanwhile, measurement restriction (MR) means that channel measurement or interference measurement is performed only within a limited period (time domain and/or frequency domain). The base station operating the above-described second CSI-RS mode may have to change the beam applied to the CSI-RS AP according to time due to a change in a channel or a change in terminals sharing CSI-RS resources.

A method of applying MR in the time domain is described with reference to FIGS. 3A and 3B . Specifically, FIG. 3A shows a case in which an explicit measurement reset is not set, and FIG. 3B shows a case in which an explicit measurement reset is set.

As illustrated in FIG. 3A , the UE measures a channel used for CSI calculation in X NZP CSI-RS subframes (including CSI reference resources) up to a CSI reference resource. The UE measures interference used in CSI calculation in Y CSI-IM subframes (including CSI reference resources) up to a CSI reference resource when CSI-IM is configured, and when CSI-IM is not configured, CSI reference Up to resources are measured in V valid DL subframes (including CSI reference resources) or valid special subframes (including CSI reference resources).

Whether or not to apply MR may be set by higher-layer signaling, and MR for channel measurement and MR for interference measurement may be set independently of each other. Each of the values of X, Y, and V may be defined as a fixed value (method M600), set through higher-layer signaling, or determined within a certain range by the terminal (method M601).

A method for the terminal to set each value of X, Y, and V within a certain range will be described with reference to FIG. 3B . For example, a predetermined range for X may be 1 to Z _X , a predetermined range for Y may be 1 to Z _Y , and a predetermined range for V may be 1 to Z _V . Here, Z _X , Z _Y , Z _V are between the most recently reset measurement subframe and the CSI reference resource (specifically, the interval from the most recently reset measurement subframe to the subframe to which the CSI reference resource belongs) may be the number of CSI-RS subframes. A period and an offset may be set by higher-layer signaling so that a subframe in which measurement is reset (a measurement reset subframe) is constantly repeated. For example, the most recently reset subframe is the 5th subframe of the 10th frame, the CSI reference resource is the 5th subframe of the 15th frame, and the NZP CSI-RS subframe (channel measurement is When the period of MR time for MR) or CSI-IM subframe (time MR for interference measurement) is 5 subframes, Z _X or Z _Y may be 10, and the UE selects one of the numbers from 1 to 10 as the value of X or Y (in FIG. 3B, W indicates the selected value), and applies it to MR for channel measurement or interference measurement .

When the above-described periodic measurement reset is set (method M602), the base station changes the beam(s) applied to the CSI-RS AP(s) belonging to the CSI-RS resource, the subframe in which the measurement is reset or its It can be performed in the previous most recent NZP CSI-RS subframe (when MR for channel measurement). Alternatively, when the above-described periodic measurement reset is set, the base station changes the beam(s) applied to the CSI-RS AP(s) belonging to the CSI-RS resource, the CSI-IM subframe (for interference measurement) MR) can be performed. The UE may not expect that the period of measurement reset (hereinafter, 'first measurement reset') for PUCCH-based periodic CSI reporting is set to be smaller than the beam selection reporting period. Also, such that the period of the first measurement reset is an integer multiple of the beam selection reporting period, the integer multiple value may be included in the corresponding higher-layer signaling as a period setting parameter of the first measurement reset. Alternatively, the period of the first measurement reset is not explicitly set, but may be defined as the same as the beam selection reporting period or as many as an integer multiple (predetermined integer multiple) of the beam selection reporting period. Alternatively, the subframe of the first measurement reset may be defined as a beam selection reporting subframe.

From a system point of view, the BF CSI-RS resource (which may be defined as an NZP CSI-RS resource or an NZP CSI-RS AP group in '5. CSI Process Setting Method' described above) may be shared by a plurality of terminals. and the UE may be configured with a plurality of BF CSI-RS resources. For this case, when the base station sets up MR by higher-layer signaling or when setting up a CSI process, the X, Y, V, And/or information on the measurement reset configuration (period and/or offset of the measurement reset subframe) may be included in the MR configuration or the CSI process configuration. For example, the first terminal is configured with two BF CSI-RS resources, the first BF CSI-RS resource among the BF CSI-RS resources is shared by the first terminal and the second terminal, and the second BF CSI When the -RS resource is shared by the first terminal and the third terminal, X for the first BF CSI-RS resource may be set to 2, and X for the second BF CSI-RS resource may be set to 4.

Examples of using MR may include: '5. MR may not be applied to the channel measurement of the first CSI-RS mode described above in 'How to set up the CSI process', and method M600 in which Y=1 may be applied to the interference measurement. Method M600 or method M602 of Y=1 may be applied to channel measurement in the second CSI-RS mode, and method M600 of Y=1 may be applied to interference measurement.

In configuring the plurality of CSI processes, when aperiodic CSI reporting for the plurality of CSI processes is simultaneously requested by the base station and all MRs for the corresponding CSI processes are configured, the terminal is configured to perform the ratio of the CSI processes. CSI-RS for periodic CSI reporting may not be expected to be configured through the same CSI-RS resource configuration.

7. A base station and a terminal performing the above-described methods

4 shows a base station 100 for transmitting a CSI-RS according to an embodiment of the present invention.

The base station 100 illustrated in FIG. 4 includes a radio frequency (RF) converter 130 , a processor 110 , a memory 120 , and an antenna module 140 .

The processor 110 may be configured to implement the functions, procedures, and methods described herein in connection with a base station. In addition, the processor 110 may control each configuration of the base station 100 .

The memory 120 is connected to the processor 110 and stores various information related to the operation of the processor 110 .

The RF converter 130 is connected to the processor 110 and transmits or receives a wireless signal. The RF converter 130 includes a transmitting module 131 and a receiving module 132 .

The base station 100 receives the CSI report from the terminal through the reception module 132 .

The base station 100 stores, in the memory 120 , information necessary for CSI-RS configuration, information necessary for CSI measurement & reporting configuration, and/or configured information. In addition, the base station 100 stores the CSI reported from the terminal in the memory 120 .

The base station 100, through the processor 110, performs CSI-RS configuration and CSI measurement & reporting configuration suitable for the terminal according to the methods described herein.

The base station 100 transmits the CSI-RS configuration information, the CSI measurement & report configuration information, and the CSI-RS according to the transmission module 130 .

5 shows a terminal 200 for measuring and reporting CSI according to an embodiment of the present invention.

The terminal 200 illustrated in FIG. 5 includes an RF converter 230 , a processor 210 , a memory 220 , and an antenna module 240 .

The processor 210 may be configured to implement the functions, procedures, and methods described herein with respect to the terminal. In addition, the processor 210 may control each configuration of the terminal 200 .

The memory 220 is connected to the processor 210 and stores various information related to the operation of the processor 210 .

The RF converter 230 is connected to the processor 210 and transmits or receives a wireless signal. The RF converter 230 includes a transmitting module 231 and a receiving module 232 .

The terminal 200 receives CSI-RS configuration information, CSI measurement & report configuration information, and CSI-RS according to the CSI-RS configuration information from the base station 100 through the reception module 232 .

The terminal 200 stores the received CSI-RS configuration information and CSI measurement & report configuration information in the memory 220 .

The terminal 200, through the processor 210, measures CSI from the CSI-RS according to the methods described herein. The terminal 200 stores the measured CSI in the memory 220 .

The terminal 200 reports on the CSI stored in the memory 220 according to the methods described herein, through the processor 210 .

The terminal 200 transmits the CSI to be reported to the base station 100 through the transmission module 231 .

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the right.

Claims (20)

In a method for a UE to report channel state information (CSI) to a base station in a multiple input multiple output (MIMO) antenna system,
When the first CSI-RS (reference signal) mode is operated in the base station, a plurality of first identifiers indicating a plurality of CSI-RS resource configurations are paired with each of the plurality of first identifiers, and a plurality of first identifiers are formed. 1 CSI-IM (interference measurement) receiving from the base station first CSI process configuration information including a plurality of second identifiers indicating resource configuration;
measuring a first CSI according to the first CSI process configuration information; and
According to the first CSI process configuration information, one third identifier corresponding to the first CSI-RS resource among the plurality of CSI-RS resources corresponding to the plurality of first identifiers and the first CSI-RS resource The first CSI or a plurality of fourth identifiers corresponding to a plurality of second CSI-RS resources among a plurality of CSI-RS resources corresponding to the plurality of first identifiers and the plurality of second CSI-RS resources Including the step of reporting the first CSI to the base station
Reporting method of the terminal. The method of claim 1,
When the first CSI-RS mode is operated, the first CSI-RS and the second CSI-RS transmitted on the same CSI-RS resource set in the first CSI process configuration information are beamformed in the same beam direction, and the The third CSI-RS and the fourth CSI-RS transmitted on different CSI-RS resources set in the first CSI process configuration information are beamformed in different beam directions.
Reporting method of the terminal. According to claim 1,
The measuring comprises measuring a precoding matrix indicator (PMI), a rank indicator (RI) and a channel quality indicator (CQI) for the first CSI-RS resource or the plurality of second CSI-RS resources.
Reporting method of the terminal. 4. The method of claim 3,
The first CSI-RS resource corresponds to one selected beam, and the plurality of second CSI-RS resources corresponds to a plurality of selected beams.
Reporting method of the terminal. According to claim 1,
The reporting step is
when the third identifier is reported, transmitting the third identifier and the first CSI for the third identifier to the base station; and
When the plurality of fourth identifiers are reported, transmitting a bitmap indicating the plurality of fourth identifiers and the first CSI for the plurality of fourth identifiers to the base station
Reporting method of the terminal. The method of claim 1,
When operating in the second CSI-RS mode, a second CSI process setting including a plurality of fifth identifiers indicating a plurality of second CSI-RS resource configurations and a sixth identifier indicating one second CSI-IM resource configuration receiving information from the base station;
measuring a second CSI according to the second CSI process configuration information; and
Transmitting the second CSI to the base station according to the second CSI process configuration information
Reporting method of the terminal. 7. The method of claim 6,
When operating in the second CSI-RS mode, a plurality of CSI-RSs transmitted on a plurality of CSI-RS resources set in the second CSI process configuration information are beamformed in the same beam width and beam direction.
Reporting method of the terminal. 6. The method of claim 5,
At least one demodulation reference signal (DM-RS) antenna port and at least one first first belonging to at least one CSI-RS resource indicated by the third identifier or the plurality of fourth identifiers transmitted from the base station Assuming that the QCL for all or part of a Doppler shift, a Doppler spread, an average delay, and a delay spread between the CSI-RS resources is satisfied. doing
Reporting method of the terminal. 6. The method of claim 5,
For a CSI process corresponding to quasi co-location (QCL) information configured in the terminal through physical layer signaling from the base station for physical downlink shared channel (PDSCH) reception, at least one first DM-RS antenna port and the Doppler shift, Doppler spread, average delay between at least one first CSI-RS resource belonging to at least one CSI-RS resource indicated by the third identifier or the plurality of fourth identifiers transmitted from the base station, Assuming that the QCL for all or part of the delay spread is satisfied,
The at least one first DM-RS antenna port belongs to a PDSCH transmission resource allocated by DL (downlink) DCI (downlink control information) including QCL information.
Reporting method of the terminal. delete delete delete In a multiple input multiple output (MIMO) antenna system, a method for a base station to set a process of channel state information (CSI) to a terminal, comprising:
When operating in a first CSI-RS (reference signal) mode, a plurality of first identifiers indicating a plurality of CSI-RS resource configurations are paired with each of the plurality of first identifiers, and a plurality of first identifiers are formed. including a plurality of second identifiers indicating an interference measurement (CSI-IM) resource configuration in the first CSI process setting information;
setting the first CSI process configuration information to the terminal; and
Receiving the first CSI measured according to the first CSI process configuration information from the terminal
A method of setting a base station comprising a. 14. The method of claim 13,
When operating in the first CSI-RS mode, the first CSI-RS and the second CSI-RS transmitted on the same CSI-RS resource set in the first CSI process configuration information are beamformed in the same beam direction, A third CSI-RS and a fourth CSI-RS transmitted on different CSI-RS resources set in the first CSI process configuration information are beamformed in different beam directions.
How to set up a base station. 14. The method of claim 13,
The receiving may include one third identifier corresponding to a first CSI-RS resource among a plurality of CSI-RS resources corresponding to the plurality of first identifiers, or a plurality of CSI- corresponding to the plurality of first identifiers. Receiving a plurality of fourth identifiers corresponding to a plurality of second CSI-RS resources among RS resources
How to set up a base station. 16. The method of claim 15,
The first CSI-RS resource corresponds to one first beam selected by the terminal, and the plurality of second CSI-RS resources corresponds to a plurality of second beams selected by the terminal.
How to set up a base station. 14. The method of claim 13,
When operating in the second CSI-RS mode, a plurality of fifth identifiers indicating a plurality of second CSI-RS resource configurations and a sixth identifier indicating one second CSI-IM resource configuration are assigned to the second CSI process configuration information including in the;
transmitting the second CSI process configuration information to the terminal; and
Receiving the second CSI measured according to the second CSI process configuration information from the terminal further comprising
How to set up a base station. 18. The method of claim 17,
When operating in the second CSI-RS mode, a plurality of CSI-RSs transmitted on the plurality of CSI-RS resources set in the second CSI process configuration information are beamformed in the same beamwidth and beam direction.
How to set up a base station. 18. The method of claim 17,
selecting one of the first CSI-RS mode and the second CSI-RS mode; and
Further comprising the step of operating the selected mode
How to set up a base station.
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