WO2015020505A1 - Method and device for transmitting reference signal in wireless communication system - Google Patents

Abstract

A method and a device for transmitting a reference signal in a wireless communication system are provided. A base station (BS) transmits a channel state information (CSI) reference signal (RS) resource configuration indicator, which corresponds to any one of an existing CSI-RS configuration set and an additional CSI-RS configuration set, to a mobile station (MS). According to a CSI-RS pattern of any one of the existing CSI-RS configuration set and the additional CSI-RS configuration set, which is selected on the basis of the CSI-RS resource configuration indicator, the base station (BS) maps a generated CSI-RS sequence to resource elements in a subframe using a modulation symbol and then transmits the mapped CSI-RS sequence.

Description

Method and apparatus for transmitting a reference signal in a wireless communication system

The present invention relates to wireless communication, and more particularly, to a method and apparatus for transmitting a reference signal in a wireless communication system.

UMTS (Universal Mobile Telecommunications System) is a third generation (3rd generation) operating in wideband code division multiple access (WCDMA) based on European systems such as global system for mobile communications (GSM) and general packet radio services (GPRS). generation Asynchronous mobile communication system. Long-term evolution (LTE) and LTE-advanced (LTE-A) as a 4th generation mobile communication system are under discussion by the 3rd generation partnership project (3GPP) that has standardized UMTS.

Component carrier (CC) used in a conventional multiple carrier system (CC) is important to the versatility of the physical layer, there is overlap of the control region and common signal overhead. Therefore, there are problems such as unnecessary resources in terms of spectral efficiency due to the reduction of resources for the data signal. Accordingly, in order to efficiently operate the multi-carrier system, it is required to introduce a new carrier type (NCT) constituting the multi-carrier system. In the NCT, a reference signal (RS) for a downlink control channel or a channel estimation is compared with a legacy carrier type (LCT) within a range of minimizing or minimizing performance. Can be removed or reduced. This is to obtain the maximum data transmission efficiency. The conventional conventional carrier type (LCT) is also referred to as backward compatible carrier type (BCCT) by distinguishing it from NCT.

The NCT may include non-standalone NCT and standalone NCT. Non-alone NCT is an NCT that may not exist in the form of a single cell, but may exist in the form of a secondary serving cell (SCell) when a primary serving cell (PCell) exists. On the other hand, NCT alone is NCT that can exist in the form of a single cell. For example, the sole NCT may be in the form of a PCell. In a single NCT and a non-standalone NCT, a cell-specific RS (CRS) may not be transmitted. Accordingly, the conventional physical downlink control channel (PDCCH), the physical HARQ indicator channel (PHICH), and the physical control format indicator channel (PCFICH), which are control channels based on the CRS, may be removed or replaced with other types of channels.

1 illustrates an example of a communication system in which a high power node and a low power node are disposed.

In the next-generation communication system such as 3GPP LTE-A, a small cell based on a low-power node as well as a macro cell (F1) based on a high-power node as shown in FIG. 1. In order to provide wireless communication services to indoor and outdoor through F2), research is being conducted.

Small cells aim to increase spectral efficiency with efficient deployment and operation. The small cell may be considered both in frequency band F1 which is coverage of the macro cell and in frequency band F2 other than the coverage of the macro cell. In addition, the small cells may be provided in both indoor environments (shown as cuboids in FIG. 1) and in outdoor environments (shown outside cuboids in FIG. 1). In addition, an ideal or non-ideal backhaul network may be supported between the macro cell and the small cell and / or between the small cells. In addition, the small cell may be provided in both a low density deployment environment and / or a high density deployment environment.

In a wireless communication system, it is necessary to estimate an uplink channel or a downlink channel for data transmission / reception, system synchronization acquisition, channel information feedback, and the like. In a wireless communication system, fading occurs due to a multipath time delay. The process of restoring the transmission signal by compensating for the distortion of the signal caused by a sudden environmental change due to fading is called channel estimation. In addition, it is necessary to measure the channel state (channel state) for the cell to which the terminal belongs or other cells. For channel estimation or channel state measurement, a channel estimation is generally performed using reference signals known to each other.

The channel state information (CSI) reference signal (RS) is used for channel estimation of the physical downlink shared channel (PDSCH) of the LTE-A terminal. CSI-RSs are relatively sparse in the frequency domain or time domain. Channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), etc. may be reported from the UE when necessary through estimation of CSI.

Currently, in 3GPP LTE-A, CSI-RS is not transmitted in a special subframe of a time division duplex (TDD) frame. However, in consideration of NCT or small cell environment in the future, transmission of CSI-RS may be required even in a special subframe of a TDD frame. In addition, CSI-RS is transmitted in a normal subframe at present, but considering the NCT or small cell environment in the future, the number of configurable CSI-RS patterns is limited so that the base station configures the CSI-RS. Can increase.

Therefore, a method of increasing the number of configurable CSI-RS patterns may be required.

An object of the present invention is to provide a method and apparatus for transmitting a reference signal in a wireless communication system. The present invention provides a method for configuring a channel state information (CSI) reference signal (RS) in consideration of a new carrier type (NCT) and / or a small cell. In addition, the present invention provides a method for increasing the number of configurable CSI-RS patterns by configuring additional CSI-RS in addition to the legacy CSI-RS (CSI-RS).

In one aspect, a method is provided for transmitting a reference signal by an evolved-NodeB (eNB) in a wireless communication system. The method includes a CSI-RS resource configuration indicator corresponding to any one of an existing channel state information (CSI) reference signal (RS) configuration set or an additional CSI-RS configuration set. Transmitting to a user equipment (UE), generating a CSI-RS sequence, selected from the existing CSI-RS configuration set or the additional CSI-RS configuration set selected based on the CSI-RS resource configuration indicator; Mapping the generated CSI-RS sequence to resource elements in a subframe using a modulation symbol according to the CSI-RS pattern, and OFDM generated based on the mapped CSI-RS sequence. and transmitting an orthogonal frequency division multiplexing) signal to the terminal.

The CSI-RS resource configuration indicator may be a 1-bit radio resource control (RRC) signaling indicating either the existing CSI-RS configuration set or the additional CSI-RS configuration set.

When the value of the 1 bit is 0, the CSI-RS resource configuration indicator indicates the existing CSI-RS configuration set. When the value of the 1 bit is 1, the CSI-RS resource configuration indicator is the additional CSI-RS. Can indicate an RS configuration set.

When the value of the 1 bit is 1, the CSI-RS resource configuration indicator indicates the existing CSI-RS configuration set. When the value of the 1 bit is 0, the CSI-RS resource configuration indicator is the additional CSI-RS. RS configuration may be indicated.

The CSI-RS resource configuration indicator may be a 6-bit resourceConfig parameter indicating one of the CSI-RS patterns.

The one CSI-RS pattern may be configured according to the number of CSI-RS antenna ports.

The subframe may have a normal cyclic prefix or extended CP.

When the CSI-RS sequence is mapped according to the CSI-RS pattern of any one of the additional CSI-RS configuration sets, the resource elements include first to fourth orthogonal frequency division multiplexing (OFDM) symbols and a first symbol of a first slot. Resource elements on the first and second OFDM symbols of the two slots.

In another aspect, an evolved-NodeB (eNB) is provided in a wireless communication system. The base station includes a reference signal generator configured to generate a channel state information (CSI) reference signal (RS) sequence, an existing CSI-RS configuration set selected based on a CSI-RS resource configuration indicator, or A resource mapper configured to map the generated CSI-RS sequence to resource elements in a subframe using a modulation symbol according to the CSI-RS pattern of any one of the additional CSI-RS configuration sets, and Orthogonal frequency division multiplexing (OFDM) signal generated based on the CSI-RS resource configuration indicator and the mapped CSI-RS sequence corresponding to either the existing CSI-RS configuration set or the additional CSI-RS configuration set. And a transmitter configured to transmit to a user equipment (UE).

In another aspect, a method of performing channel estimation by a user equipment (UE) in a wireless communication system is provided. The method may include a CSI-RS resource configuration indicator corresponding to one of an existing channel state information (CSI) reference signal (RS) configuration set or an additional CSI-RS configuration set. receiving from an evolved-NodeB (eNB), receiving an orthogonal frequency division multiplexing (OFDM) signal generated based on a CSI-RS sequence, and demodulating the received OFDM signal to perform channel estimation And the CSI-RS sequence according to the CSI-RS pattern of any one of the existing CSI-RS configuration set or the additional CSI-RS configuration set selected based on the CSI-RS resource configuration indicator. The generated CSI-RS sequence is mapped to resource elements in a subframe using a modulation symbol.

In another aspect, a user equipment (UE) in a wireless communication system is provided. The UE may include a CSI-RS resource configuration indicator and a CSI-RS corresponding to any one of a channel state information (CSI) reference signal (RS) configuration set or an additional CSI-RS configuration set. A receiver configured to receive an orthogonal frequency division multiplexing (OFDM) signal generated based on an RS sequence, and a channel estimator configured to demodulate the received OFDM signal to perform channel estimation, wherein the CSI-RS sequence includes: Modulating the generated CSI-RS sequence according to the CSI-RS pattern of any one of the existing CSI-RS configuration set or the additional CSI-RS configuration set selected based on the CSI-RS resource configuration indicator; symbol) to map to resource elements in a subframe.

According to the present invention, the number of CSI-RS patterns configurable in a wireless communication system can be increased.

De 1 shows an example of a communication system in which a high power node and a low power node are disposed.

2 illustrates a wireless communication system to which an embodiment of the present invention can be applied.

3 shows a structure of a radio frame in 3GPP LTE.

4 shows an example of a resource grid for one downlink slot.

5A to 5B illustrate examples of a CSI-RS configuration and a CSI-RS pattern according to the number of CSI-RS antenna ports in a general CP.

6 shows an example of a CSI-RS configuration and a CSI-RS pattern according to the number of CSI-RS antenna ports in an extended CP.

7A-7B illustrate the mapping of DMRSs in normal CPs.

8 shows a mapping of DMRS in an extended CP.

9 and 10 illustrate a CSI-RS configuration method according to an embodiment of the present invention.

11 illustrates a CSI-RS configuration method according to another embodiment of the present invention.

12 and 13 illustrate a CSI-RS configuration method according to another embodiment of the present invention.

14 and 15 illustrate a CSI-RS configuration method according to another embodiment of the present invention.

16 illustrates a CSI-RS configuration method according to another embodiment of the present invention.

17 illustrates a CSI-RS configuration method according to another embodiment of the present invention.

18 illustrates a CSI-RS configuration method according to another embodiment of the present invention.

19 illustrates a CSI-RS configuration method according to another embodiment of the present invention.

20 is a view illustrating a method of transmitting a reference signal according to an embodiment of the present invention.

21 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.

Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

The present specification describes a communication network, and the work performed in the communication network is performed in the process of controlling the network and transmitting data in a system (for example, a base station) that manages the communication network, or a terminal linked to the network. Work can be done in

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented by a radio technology such as universal terrestrial radio access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as global system for mobile communications (GSM) / general packet radio service (GPRS) / enhanced data rates for GSM evolution (EDGE). OFDMA may be implemented by wireless technologies such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), and the like. IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e. UTRA is part of a universal mobile telecommunications system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is part of evolved UMTS (E-UMTS) using evolved-UMTS terrestrial radio access (E-UTRA), which employs OFDMA in downlink and SC in uplink -FDMA is adopted. LTE-A (advanced) is the evolution of 3GPP LTE.

For clarity, the following description focuses on LTE-A, but the technical spirit of the present invention is not limited thereto.

2 illustrates a wireless communication system to which an embodiment of the present invention can be applied.

2, the wireless communication system 10 is widely deployed to provide various communication services such as voice, packet data, and the like. The wireless communication system 10 includes at least one base station 11 (evolved-NodeB). Each base station 11 provides a communication service for a specific geographic area or frequency area and may be called a site. The site may be divided into a plurality of regions 15a, 15b, and 15c, which may be called sectors, and the sectors may have different cell IDs.

A user equipment (UE 12) may be fixed or mobile, and may have a mobile station (MS), a mobile terminal (MS), a user terminal (UT), a subscriber station (SS), a wireless device, a PDA, and the like. (personal digital assistant), wireless modem (wireless modem), a handheld device (handheld device) may be called other terms. The base station 11 generally refers to a station that communicates with the terminal 12, and includes a base station (BS), a base transceiver system (BTS), an access point, an femto eNB, and a home base station. (HeNB; home eNodeB), relay (relay), remote radio head (RRH) may be called in other terms. Cells 15a, 15b, and 15c should be interpreted in a comprehensive sense, indicating some areas covered by base station 11, and include mega cells, macro cells, micro cells, and pico. The term encompasses various coverage areas such as a pico cell and a femto cell.

A terminal typically belongs to one cell, and a cell to which the terminal belongs is called a serving cell. A base station that provides a communication service for a serving cell is called a serving BS. Since the wireless communication system is a cellular system, there are other cells adjacent to the serving cell. Another cell adjacent to the serving cell is called a neighbor cell. A base station that provides communication service for a neighbor cell is called a neighbor BS. The serving cell and the neighbor cell are relatively determined based on the terminal.

This technique can be used for downlink or uplink. In general, downlink means communication from the base station 11 to the terminal 12, and uplink means communication from the terminal 12 to the base station 11. In downlink, the transmitter may be part of the base station 11 and the receiver may be part of the terminal 12. In uplink, the transmitter may be part of the terminal 12 and the receiver may be part of the base station 11.

The wireless communication system may be any one of a multiple-input multiple-output (MIMO) system, a multiple-input single-output (MIS) system, a single-input single-output (SISO) system, and a single-input multiple-output (SIMO) system. Can be. The MIMO system uses a plurality of transmit antennas and a plurality of receive antennas. The MISO system uses multiple transmit antennas and one receive antenna. The SISO system uses one transmit antenna and one receive antenna. The SIMO system uses one transmit antenna and multiple receive antennas. Hereinafter, the transmit antenna means a physical or logical antenna used to transmit one signal or stream, and the receive antenna means a physical or logical antenna used to receive one signal or stream.

Wireless communication systems can be largely divided into frequency division duplex (FDD) and time division duplex (TDD). According to the FDD scheme, uplink transmission and downlink transmission are performed while occupying different frequency bands. According to the TDD scheme, uplink transmission and downlink transmission are performed at different times while occupying the same frequency band. The channel response of the TDD scheme is substantially reciprocal. This means that the downlink channel response and the uplink channel response are almost the same in a given frequency domain. Therefore, in a TDD based wireless communication system, the downlink channel response can be obtained from the uplink channel response. In the TDD scheme, the uplink transmission and the downlink transmission are time-divided in the entire frequency band, and thus the downlink transmission by the base station and the uplink transmission by the terminal cannot be simultaneously performed. In a TDD system in which uplink transmission and downlink transmission are divided into subframe units, uplink transmission and downlink transmission are performed in different subframes.

3 shows a structure of a radio frame in 3GPP LTE. This may be referred to 3GPP TS 36.211 V11.2.0 (2013-02).

Referring to FIG. 3, a radio frame consists of 10 subframes, and one subframe consists of two slots. Slots in a radio frame are numbered with slots # 0 through # 19. Transmission time interval (TTI) is a basic scheduling unit for data transmission. In 3GPP LTE, one TTI may be equal to the time taken for one subframe to be transmitted. One radio frame may have a length of 10 ms, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.

One slot includes a plurality of orthogonal frequency division multiplexing (OFDM) symbols in the time domain and a plurality of subcarriers in the frequency domain. The OFDM symbol is used to represent one symbol period since 3GPP LTE uses OFDMA in downlink, and may be called a different name according to a multiple access scheme. For example, when SC-FDMA is used as an uplink multiple access method, it may be referred to as an SC-FDMA symbol. A resource block (RB) includes a plurality of consecutive subcarriers in one slot in resource allocation units. The structure of the radio frame is merely an example. Accordingly, the number of subframes included in the radio frame, the number of slots included in the subframe, or the number of OFDM symbols included in the slot may be variously changed.

3GPP LTE defines that one slot includes 7 OFDM symbols in a normal cyclic prefix (CP), and one slot includes 6 OFDM symbols in an extended CP.

The downlink subframe includes two slots in the time domain, and each slot includes seven OFDM symbols in a normal CP. Up to three OFDM symbols (up to four OFDM symbols for 1.4Mhz bandwidth) of the first slot in the subframe are the control regions to which control channels are allocated, and the remaining OFDM symbols are the PDSCH (physical downlink shared channel). Becomes the data area to be allocated.

4 shows an example of a resource grid for one downlink slot.

The downlink slot includes a plurality of OFDM symbols in the time domain and N _RB resource blocks in the frequency domain. The number N _RB of resource blocks included in the downlink slot depends on the downlink transmission bandwidth set in the cell. For example, N _RB in 3GPP LTE may be any one of 6 to 110. One resource block includes a plurality of subcarriers in the frequency domain. The structure of the uplink slot may also be the same as that of the downlink slot.

Each element on the resource grid is called a resource element (RE). Resource elements on the resource grid may be identified by an index pair (k, l) in the slot. Where k (k = 0, ..., N _RB × 12-1) is the subcarrier index in the frequency domain and l (l = 0, ..., 6) is the OFDM symbol index in the time domain.

Here, one resource block corresponds to one slot of 0.5 ms in the time domain, and corresponds to a total of 12 subcarriers when the frequency spacing between each subcarrier is 15 Khz at 180 Khz in the frequency domain. In FIG. 4, one resource block includes 7 × 12 resource elements including 7 OFDM symbols in the time domain and 12 subcarriers in the frequency domain, but the number of OFDM symbols and the number of subcarriers in the resource block is exemplarily described. Is not limited thereto. The number of OFDM symbols and the number of subcarriers can be variously changed according to the length of the CP, the frequency interval, and the like. For example, the number of OFDM symbols is 7 for a normal CP and the number of OFDM symbols is 6 for an extended CP.

In addition, two resource blocks physically allocated in one subframe on the time axis may be referred to as a physical resource block (PRB) -pair.

Reference signal (RS) is generally transmitted in sequence. As the reference signal sequence, a sequence having excellent correlation property may be used. As an example, the reference signal sequence may use a constant amplitude zero auto-correlation (CAZAC) sequence. The CAZAC sequence includes a ZCoff-based sequence or the like, and the ZC-based sequence may be cyclically extended or truncated according to a purpose. As another example, the reference signal sequence may use a pseudo-random (PN) sequence. PN sequences include m-sequences, computer-generated PN sequences, gold sequences, and Kasami sequences.

The downlink reference signal may include a cell-specific RS (CRS), a multimedia broadcast and multicast single frequency network (MBSFN) reference signal, a UE-specific RS, and a position reference signal (PRS). RS and channel state information (CSI) reference signals (CSI-RS). The CRS is a reference signal transmitted to all UEs in a cell. The CRS may be used for channel measurement for channel quality indicator (CQI) feedback and channel estimation for PDSCH. The MBSFN reference signal may be transmitted in a subframe allocated for MBSFN transmission. The UE-specific reference signal is a reference signal received by a specific terminal or a specific group of terminals in a cell, and may be referred to as a demodulation RS (DMRS). In DMRS, a specific terminal or a specific terminal group is mainly used for data demodulation. The PRS may be used for position estimation of the terminal. CSI-RS is used for channel estimation for PDSCH of LTE-A terminal.

The CSI-RS will be described.

The CSI-RS may be transmitted through one, two, four or eight antenna ports. In this case, the antenna ports used may be p = 15, p = 15, 16, p = 15, ..., 18 and p = 15, ..., 22, respectively. The CSI RS may be defined only for the case where the frequency interval Δf between the subcarriers is 15 kHz. CSI-RS may refer to 3GPP TS 36.211 V11.2.0 (2013-02).

The CSI-RS sequence r _{l, ns} (m) may be defined as in Equation 1.

Equation 1

In Equation 1, n _s is a slot number in a radio frame, and l is an OFDM symbol number in a slot. Referring to Equation 1, the m-th CSI-RS sequence is generated by forming a real part and an imaginary part through a pseudo-random sequence c (i), and then normalizing them. c (i) may be defined by a Gold sequence of length-31. c (i) may have a value of 0 or 1 as a binary pseudo-random sequence. Therefore, as shown in Equation 1, 1-2 · c (i) may represent a value of 1 or -1, and the 2m-th sequence corresponding to an even number in the real part and the odd number in the imaginary part (2m Use the +1) th sequence. The output sequence c (n) of length M _PN (n = 0,1, ..., M _PN- 1) may be defined as in Equation 2.

Equation 2

로 표현될 수 있다. In Equation 2, N _C = 1600, and the first m-sequence x ₁ (i) is x ₁ (0) = 1, x ₁ (n) = 0, (n = 1,2, ..., 30) Can be initialized to The initialization of the second m-sequence x ₂ (i) may be initialized to different values depending on the system parameter values used in the channel or signal to which the sequence is applied.

It can be expressed as.

The pseudo random sequence c (i) may be initialized by Equation 3 at the start of each OFDM symbol.

Equation 3

In Equation 3, N _CP has a value of 1 in a general CP and 0 in an extended CP. The N _ID ^CSI may have any one of integers from 0 to 503. The N _ID ^CSI may be a virtual cell ID (VCID) for CSI-RS when signaled from a higher layer. The N _ID ^CSI may be equal to a physical cell ID (PCI) if there is no signaling from a higher layer.

In a subframe configured for transmission of the CSI-RS, the CSI-RS sequence r _{l, ns} (m) is a complex-valued modulation symbol a _k used as a reference symbol on the antenna port p according to Equation 4. _{, l} ^(p) can be mapped.

Equation 4

및 직교 시퀀스 w_l''가 곱하여져 맵핑된다.Referring to Equation ^{_{4, a k, l (p}} ) is the complex modulation symbols are mapped to sub-carrier k and l th OFDM symbol in the p th antenna port. a _{k, l} ^(p) is the CSI-RS sequence

And orthogonal sequence w _{l ''} are multiplied and mapped.

Each parameter of Equation 4 may be defined by Equation 5.

Equation 5

Referring to Equation 5, the requirements for (k ', l') and n _s can be given by Tables 1 and 2 described below.

The CSI-RS configuration includes a non-zero transmission power CSI-RS configuration indicating a pattern in which a CSI-RS is transmitted to a terminal of each cell (or transmission point (TP)), and a neighboring cell (or It may be classified into a zero transmission power CSI-RS configuration for muting a PDSCH region corresponding to CSI-RS transmission of TP). Zero or one CSI-RS configuration per CSI process may be used for a terminal assuming non-zero power CSI-RS, and zero or several CSI RS configurations may be used for a terminal assuming zero power CSI-RS.

Information about one or more non-zero power CSI-RS configuration (hereinafter, referred to as CSI-RS configuration) may be transmitted to each terminal of the corresponding cell. The information on the CSI-RS configuration includes 2-bit information indicating whether the number of antenna ports (hereinafter, CSI-RS antenna ports) for transmitting non-zero power CSI-RS is any one of 1, 2, 4, and 8; 5 bit information indicating a CSI-RS pattern configurable for each number of CSI-RS antenna ports may be included.

Table 1 shows the mapping of the CSI-RS configuration and (k ', l'), that is, the CSI-RS pattern of Equation 5 in the general CP, and Table 2 shows the CSI-RS configuration and (k) ', l'), that is, mapping of the CSI-RS pattern.

Table 1

TABLE 2

In Table 1 and Table 2, frame structure type 1 means FDD and frame structure type 2 means TDD.

Referring to Table 1, in case of a general CP, 32 CSI-RS configurations are used when the number of antenna ports is 1 or 2, 16 CSI-RS configurations are used when the number of antenna ports is 4, and the number of antenna ports is There are eight CSI-RS configurations when there are eight. Referring to Table 2, in case of the extended CP, 28 CSI-RS configurations in total with one or two antenna ports, 14 CSI-RS configurations in total with four antenna ports, and the number of antenna ports In eight, there are a total of seven CSI-RS configurations.

Referring to Tables 1 and 2, the location of one specific resource element to which the CSI-RS is mapped may be indicated for each CSI-RS antenna port with respect to the CSI-RS configuration. That is, the location of the remaining resource elements to which the CSI-RS is mapped may be determined by Equation 5 based on the location of the one specific resource element, and thus, the total CSI-RS configurable for each number of CSI-RS antenna ports. The pattern can be seen.

For example, if the number of CSI-RS antenna ports is 8 and the value of the CSI-RS configuration is 2 (= 00010), corresponding to (k ', l') = (9,2) according to Table 1 And n _s mod 2 = 1. Accordingly, it can be seen that within the subframe configured for CSI-RS transmission, the CSI-RS is mapped to a resource element having a subcarrier index of 9 and an OFDM symbol index of 2 in the second slot. The resource element indicated by Table 1 may be one of locations of resource elements to which CSI-RSs transmitted through the first CSI-RS antenna port are mapped. The positions of the remaining resource elements to which the CSI-RSs transmitted through the first CSI-RS antenna port are mapped and the positions of the resource elements to which the CSI-RSs are transmitted through the remaining CSI-RS antenna port are mapped according to Equation (5). It may be located at a predetermined distance from the resource element indicated by 1.

5 shows an example of a CSI-RS configuration and a CSI-RS pattern according to the number of CSI-RS antenna ports in a general CP.

FIG. 5A illustrates a CSI-RS pattern in the case of FDD + TDD and FIG. 5B in the case of TDD. In FIG. 5, the number indicated on each resource element represents a CSI-RS configuration number. a is CSI-RS antenna port {15, 16}, b is CSI-RS antenna port {17, 18}, c is CSI-RS antenna port {19, 20}, d is CSI-RS antenna port {19, 20 } This shows transmitting the CSI-RS. A denotes DMRS antenna ports {7, 8, 11, 13}, and B denotes transmission of DMRS on DMRS antenna ports {9, 10, 12, 14}. C represents a resource element to which the CRS is mapped. In addition, in FIG. 5, it is assumed that the number of CRS antenna ports is two, and the control region (shading part) is allocated to the first three OFDM symbols of the subframe.

The CSI-RS pattern of FIG. 5 may be applied even when the number of CRS antenna ports is one or four, or when the CRS is not transmitted. In addition, the CSI-RS pattern of FIG. 5 may be applied even when a control region is allocated to an OFDM symbol in the first 1 to 4 subframes, or when a control region is not allocated. In addition, in FIG. 5, DMRS uses two code division multiplexing (CDM) groups (A: DMRS antenna ports {7, 8, 11, 13}, and B: DMRS antenna ports {9, 10, 12, 14}). Although assumed, the CSI-RS pattern of FIG. 5 may be applied even when using one CDM group.

6 shows an example of a CSI-RS configuration and a CSI-RS pattern according to the number of CSI-RS antenna ports in an extended CP.

As in FIG. 5, the numbers indicated in each resource element in FIG. 6 indicate CSI-RS configuration numbers. a is CSI-RS antenna port {15, 16}, b is CSI-RS antenna port {17, 18}, c is CSI-RS antenna port {19, 20}, d is CSI-RS antenna port {19, 20 } This shows transmitting the CSI-RS. E indicates transmitting DMRS on DMRS antenna port {7, 8}. C represents a resource element to which the CRS is mapped. In addition, in FIG. 6, it is assumed that the number of CRS antenna ports is two, and the control region (shading part) is allocated to the first three OFDM symbols of the subframe.

The CSI-RS pattern of FIG. 6 may be applied even when the number of CRS antenna ports is one or four or when no CRS is transmitted. In addition, the CSI-RS pattern of FIG. 6 may be applied even when a control region is allocated to an OFDM symbol in the first 1 to 4 of the subframe, or when the control region is not allocated.

Hereinafter, the matters related to the CRS, the control region, and the DMRS applied in FIGS. 5 and 6 may be equally applied to the embodiments of the present invention described below.

The terminal may transmit the CSI-RS only in the downlink slot that satisfies the condition of n _s mod 2 in Table 1 and Table 2. In addition, the UE is a subframe or paging in which a special subframe of the TDD frame, transmission of the CSI-RS collides with a synchronization signal, a physical broadcast channel (PBCH), and a system information block type 1 (SystemInformationBlockType1). The CSI-RS is not transmitted in the subframe in which the message is transmitted. Also, in a set S where S = {15}, S = {15, 16}, S = {17, 18}, S = {19, 20} or S = {21, 22}, the antennas in one set S The resource element used for transmission of the CSI-RS on the port is not used for transmission of the CSI-RS on the antenna port in the PDSCH or another set S in the same slot.

Table 3 shows an example of a subframe configuration in which the CSI-RS is transmitted.

TABLE 3 CSI-RS-SubframeConfigI _CSI-RS CSI-RS CycleT _CSI-RS (subframe) CSI-RS subframe offset Δ _CSI-RS (subframes) 0-4 5 I _CSI-RS 5-14 10 I _CSI-RS -5 15-34 20 I _CSI-RS -15 35-74 40 I _CSI-RS -35 75-154 80 I _CSI-RS -75

Referring to Table 3, a period (T _CSI-RS ) and an offset (Δ _CSI-RS ) of a subframe in which the CSI-RS is transmitted may be determined according to the CSI-RS subframe configuration (I _CSI-RS ). The CSI-RS subframe configuration may be configured separately for the non-zero power CSI-RS and zero-power CSI-RS. On the other hand, the subframe for transmitting the CSI-RS needs to satisfy the equation (6).

Equation 6

The following parameters may be signaled from a higher layer such as RRC (radio resource control) for CSI-RS.

1) antennaPortsCount: It has a length of 2 bits and indicates the number of CSI-RS antenna ports in Table 1 or Table 2.

2) resouceConfig: has a length of 5 bits, and indicates the CSI-RS configuration and corresponding resource elements, that is, the CSI-RS pattern in Table 1 or Table 2.

3) subframeConfig: has a length of 8 bits, and indicates the CSI-RS subframe configuration in Table 3.

4) Pc: indicates a value related to the CSI-RS transmission power.

In addition, when considering a coordinated multi point (CoMP) transmission environment, the N _ID ^CSI of Equation 3 may be signaled from an upper layer.

The zero power CSI-RS configuration may include a 16-bit bitmap corresponding to the CSI-RS pattern when each bit has four CSI-RS antenna ports. That is, for a bit set to 1 in a 16-bit bitmap configured by a higher layer, the UE selects a resource element corresponding to the case where the number of CSI-RS antenna ports is 4 in Tables 1 and 2, and zero-power CSI-. Can be set to RS. More specifically, the most significant bit (MSB) of the 16-bit bitmap corresponds to the first CSI-RS configuration index when the number of CSI-RS antenna ports is 4 in Tables 1 and 2. Subsequent bits of the 16-bit bitmap correspond to the direction in which the CSI-RS configuration index increases when the number of CSI-RS antenna ports is 4 in Tables 1 and 2. The resource element set to the zero power CSI-RS may mute the PDSCH corresponding to the CSI-RS transmission of the neighbor cell or the TP, and transmit the PDSCH to the resource element not set to the zero power CSI-RS.

The parameters transmitted in the RRC layer for zero power CSI-RS are as follows.

1) Zero power CSI-RS configuration list: 16-bit bitmap composed of one CSI-RS configuration as one bit when the number of CSI-RS antenna ports is 4 in Table 1 or Table 2.

2) Zero Power CSI-RS Subframe Configuration (I _CSI-RS ): Like the subframeConfig parameter transmitted for the CSI-RS, it indicates the subframe configuration for the zero power CSI-RS. The zero-power CSI-RS subframe configuration has a length of 8 bits, and the period (T _CSI-RS ) and offset ( Δ _CSI-RS ) can be determined.

Table 4 shows a configuration of a special subframe within a TDD frame of 3GPP LTE.

Table 4

Referring to Table 4, the configuration of the special subframe in the TDD frame is composed of nine in the normal (cyclic prefix), and seven in the extended (extended) CP. In case of a normal CP, configuration 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9 are each of 14 orthogonal frequency division multiplexing (OFDM) symbols of one special subframe (DwPTS, guard period, The number of OFDM symbols for UpPTS) is (3, 10, 1), (9, 4, 1), (10, 3, 1), (11, 2, 1), (12, 1, 1), Indicates that it is (3, 9, 2), (9, 3, 2), (10, 2, 2), (11, 1, 2), (6, 6, 2). In the case of the extended CP, configurations 0, 1, 2, 3, 4, 5, 6, and 7 each have the number of OFDM symbols for (DwPTS, guard period, UpPTS) among 12 OFDM symbols of one special subframe. (3, 8, 1), (8, 3, 1), (9, 2, 1), (10, 1, 1), (3, 7, 2), (8, 2, 2), (9 , 1, 2), (5, 5, 2).

DMRS is demonstrated.

DMRS is supported for transmission of the PDSCH and may be transmitted on antenna ports p = 5, p = 7, p = 8 or p = 7,8, ..., v + 6. Where v is the number of layers used for transmission of the PDSCH. That is, in case of using one layer for transmission of PDSCH, DMRS may be transmitted on antenna ports 7 or 8. In addition, up to eight DMRS antenna ports may be used depending on the number of layers. DMRS may exist and be valid for PDSCH demodulation only if PDSCH transmission is associated with the corresponding antenna port. DMRS may be transmitted only on the RB to which the corresponding PDSCH is mapped.

7 shows a mapping of DMRS in a normal CP.

In FIG. 7, Rx indicates transmitting DMRS on antenna port x. For example, R ₇ represents the transfer of DMRS onto the antenna port 7. A total of 12 resource elements per DMRS antenna port may be used in a PRB pair defined as one PRB on the frequency axis and one subframe on the time axis.

7- (a) shows the mapping of DMRSs to antenna ports 7 and 8, and FIG. 7- (b) shows the mapping of DMRSs to antenna ports 9 and 10. FIG. Referring to FIG. 7, DMRSs transmitted on antenna ports 7, 8, 11, and 13 are mapped to the same resource elements on time-frequency, which may be referred to as CDM group 1. That is, R ₇ , R ₈ , R ₁₁ , and R ₁₃ may all be mapped to resource elements at the same location. In FIG. 7, R ₁₁ and R ₁₃ are not shown, but R ₁₁ and R ₁₃ may be mapped to resource elements at the same location as R ₇ and R ₈ . In addition, DMRSs transmitted on antenna ports 9, 10, 12, and 14 are also mapped to the same resource elements in time-frequency, which may be referred to as CDM group 2. That is, R ₉ , R ₁₀ , R ₁₂ , and R ₁₄ are all mapped to resource elements at the same location. In FIG. 7, although R ₁₂ and R ₁₄ are not shown, all of R ₁₂ and R ₁₄ may be mapped to resource elements at the same positions as R ₉ and R ₁₀ .

That is, CDM group 1 and CDM group 2 may be divided into positions of different resource elements on time-frequency. This may be referred to as frequency division multiplexing (FDM) and time division multiplexing (TDM) based division. In addition, antenna ports in one CDM group mapped to the same resource elements on time-frequency may be distinguished by orthogonal sequences such as orthogonal cover codes (OCCs) of Table 5. This can be called a CDM-based division.

Table 5 OCC (length = 4) [abcd] OCC A [+1 +1 +1 +1] OCC B [+1 -1 +1 -1] OCC C [+1 +1 -1 -1] OCC D [+1 -1 -1 +1]

Referring to Table 5, antenna ports 7, 8, 11, and 13 in CDM group 1 may be divided into OCCs A, B, C, and D having a length of 4, respectively, and antenna ports 9, 10, and 12 in CDM group 2. , 14 degrees may be divided into OCC A, B, C, D having a length of 4, respectively.

As shown in Table 5, an OCC having a length of 4 may be applied over four OFDM symbols in one subframe on a time axis. For example, in a general subframe using a normal CP, four OFDM symbols to which the OCC is applied are the sixth, seventh, thirteenth, and fourteenth OFDM as in the subframe of the third row of FIG. 7- (a). Symbol (OFDM symbol indexes # 5, # 6 of the first slot and OFDM symbol indexes # 5, # 6 of the second slot). Alternatively, in a special subframe using a general CP and having a special subframe configuration of any one of 3, 4, or 8, four OFDM symbols to which an OCC is applied are as shown in the second subframe of FIG. 7- (a). Third, fourth, tenth, and eleventh OFDM symbols (OFDM symbol indexes # 2, # 3 of the first slot and OFDM symbol indexes # 2, # 3 of the second slot). Alternatively, in a special subframe using a general CP and having a special subframe configuration of any one of 1, 2, 6, or 7, the four OFDM symbols to which the OCC is applied are subframes in the first row of FIG. 7- (a). As shown, the third, fourth, sixth, and seventh OFDM symbols (OFDM symbol indexes # 2, # 3, # 5, and # 6 of the first slot) may be used.

The OCC having a length of 2 may be applied over two OFDM symbols in one subframe on the time axis. For example, in a special subframe using a general CP and having a special subframe configuration of 9, two OFDM symbols to which an OCC is applied are the third and fourth OFDM symbols (OFDM symbol indexes # 2 and # 3 of the first slot). May be).

8 shows a mapping of DMRS in an extended CP.

In FIG. 8, Rx indicates transmitting DMRS on antenna port x. For example, R ₇ represents transmitting DMRS on antenna port 7. A total of 16 resource elements may be used per DMRS antenna port in a PRB pair defined as one PRB on the frequency axis and one subframe on the time axis. Referring to FIG. 8, DMRSs transmitted on antenna ports 7 and 8 are mapped to the same resource elements on time-frequency. DMRS on antenna ports 9-14 in the extended CP is not supported. Antenna ports 7 and 8 may be distinguished by OCCs having a length of 2 in Table 6.

Table 6 OCC (length = 2) [ab] OCC A [+1 +1] OCC B [+1 -1]

Hereinafter, a CSI-RS configuration method according to embodiments of the present invention will be described. In the following description, the CSI-RS pattern indicates the type of REs used for CSI-RS transmission according to the number of CSI-RS antenna ports indicated by the antennaPortsCount parameter in a specific subframe indicated by the subframeConfig parameter. Therefore, as described above, the CSI-RS pattern may be used in the same meaning as the resource configuration corresponding to the type of REs used for CSI-RS transmission in a specific subframe indicated by the resourceConfig parameter. That is, in the following description, the CSI-RS pattern and the CSI-RS resource configuration may be used as the same meaning.

First, a method of increasing the number of configurable CSI-RS patterns in a subframe having a general CP up to 2 times according to an embodiment of the present invention is described. As described above, a total of 32 CSI-RS patterns when the number of CSI-RS antenna ports is 1 or 2 in a subframe having a general CP, and a total of 16 CSI when the number of CSI-RS antenna ports is 4 When the number of -RS patterns and the number of CSI-RS antenna ports is 8, a total of 8 CSI-RS patterns exist. This may be indicated by a 5-bit resourceConfig parameter signaled via RRC.

According to an embodiment of the present invention, when the number of CSI-RS antenna ports is 1 or 2 in a subframe having a general CP, 32 (or 28) CSI-RS patterns are added to total 64 ( Or 60 CSI-RS patterns may be configured. In addition, when the number of CSI-RS antenna ports is 4 in a subframe having a general CP, 16 (or 14) CSI-RS patterns are added to total 32 (or 30) CSI-RS patterns. Can be configured. In addition, when the number of CSI-RS antenna ports is 8 in a subframe having a general CP, 8 (or 7) CSI-RS patterns are added to total 16 (or 15) CSI-RS patterns. Can be configured.

9 and 10 illustrate a CSI-RS configuration method according to an embodiment of the present invention. 9 and 10 illustrate REs in which an existing CSI-RS pattern may be configured and REs in which an additional CSI-RS pattern may be configured in a subframe having a general CP. In FIGS. 9 and 10, REs shown in dark gray are REs to which an existing CSI-RS pattern (legacy CSI-RS pattern) may be configured, and REs shown in light gray are configured to newly add a CSI-RS pattern. REs that can be.

Referring to FIG. 9, a CSI-RS pattern may be newly defined for a total of 64 REs in one PRB pair. Accordingly, as described above, when the number of CSI-RS antenna ports is 1 or 2, 32 CSI-RS patterns are added to total 64 CSI-RS patterns when the number of CSI-RS antenna ports is 4 A total of 32 CSI-RS patterns may be added by adding 16 CSI-RS patterns, and when the number of CSI-RS antenna ports is 8, 8 CSI-RS patterns may be added to form a total of 16 CSI-RS patterns. .

9- (a) and 9- (b), all REs on the 1st and 2nd OFDM symbols of the first slot within one PRB pair (total of 24 REs for each OFDM symbol) CSI-RS pattern may be configured. In addition, a newly added CSI-RS pattern among all the REs on the first and second OFDM symbols of the second slot (total of 24 REs with 12 REs for each OFDM symbol) in one PRB pair may be configured. Can be. In addition, a newly added CSI-RS pattern of some of the REs on the 3rd and 4th OFDM symbols of the first slot (a total of 16 REs with 8 REs per OFDM symbol) in one PRB pair. This can be configured. 9- (a) and 9- (b), positions of some REs to which a newly added CSI-RS pattern may be configured on the third and fourth OFDM symbols of the first slot are different. 9- (a) and 9- (b), however, the number of REs to which a newly added CSI-RS pattern can be configured on the third and fourth OFDM symbols of the first slot is 8 for each OFDM symbol. In total, 16 are the same.

9- (c) and 9- (d), as in FIGS. 9- (a) and 9- (b), on one and two OFDM symbols of a first slot in one PRB pair. A newly added CSI-RS pattern may be configured among all REs and all REs on the first and second OFDM symbols of the second slot. However, a newly added CSI-RS pattern among some REs (16 REs in total with 8 REs per OFDM symbol) among the REs on the fourth and fifth OFDM symbols of the first slot in one PRB pair. What can be configured is different from Figs. 9- (a) and 9- (b). This takes into account that the PSS may be located in the third OFDM symbol of the first slot for the six PRBs in the middle of the special subframe of the TDD frame. 9- (c) and 9- (d), positions of some REs to which a newly added CSI-RS pattern may be configured on the fourth and fifth OFDM symbols of the first slot are different from each other. 9- (c) and 9- (d), however, the number of REs to which a newly added CSI-RS pattern can be configured on the fourth and fifth OFDM symbols of the first slot is eight for each OFDM symbol. In total, 16 are the same.

Referring to FIG. 10, a CSI-RS pattern may be newly defined for a total of 56 resource elements in one PRB pair. Accordingly, as described above, when the number of CSI-RS antenna ports is 1 or 2, 28 CSI-RS patterns are added, so that when a total of 60 CSI-RS patterns are 4 and the number of CSI-RS antenna ports is 4, When 14 CSI-RS patterns are added, a total of 30 CSI-RS patterns may be added, and when the number of CSI-RS antenna ports is 7, 7 CSI-RS patterns may be added to form a total of 15 CSI-RS patterns.

Referring to FIG. 10- (a), as in FIG. 9- (a) or 9- (c), all REs and second slots on the first and second OFDM symbols of the first slot within one PRB pair. A newly added CSI-RS pattern among all REs on the first and second OFDM symbols of may be configured. However, the number of some REs for which a newly added CSI-RS pattern may be configured on the third and fourth OFDM symbols of the first slot in one PRB pair is different. That is, among the REs on the third and fourth OFDM symbols of the first slot in one PRB pair, a newly added CSI-RS pattern may be configured among eight REs, four for each OFDM symbol. Accordingly, a total of eight REs, four for each OFDM symbol, may be used, similarly to the number of REs that could form a CSI-RS pattern on an OFDM symbol in which a conventional DMRS is located.

Referring to FIG. 10- (b), as in FIG. 9- (b) or 9- (d), all REs and second slots on the first and second OFDM symbols of the first slot in one PRB pair. A newly added CSI-RS pattern among all REs on the first and second OFDM symbols of may be configured. However, the number of some REs for which a newly added CSI-RS pattern may be configured on the fourth and fifth OFDM symbols of the first slot in one PRB pair is different. That is, among the REs on the fourth and fifth OFDM symbols of the first slot in one PRB pair, a newly added CSI-RS pattern may be configured among eight REs, four for each OFDM symbol. Accordingly, a total of eight REs, four for each OFDM symbol, may be used, similarly to the number of REs that could form a CSI-RS pattern on an OFDM symbol in which a conventional DMRS is located.

Some of the REs in which the additional CSI-RS pattern described in FIG. 9 and FIG. 10 may be configured depend on the position of the DMRS defined differently according to the subframe type (general subframe and each subframe configuration). The configuration of the CSI-RS pattern may be limited. That is, even though the REs are defined in FIG. 9 and FIG. 10 so that additional CSI-RS patterns can be configured, REs overlapping the REs to which the DMRS is allocated are excluded from the REs configurable for CSI-RS transmission. However, the CSI-RS pattern is not separately defined according to the form of the subframe, and only REs used for DMRS transmission may be excluded from the REs defined so that an additional CSI-RS pattern may be configured.

11 illustrates a CSI-RS configuration method according to another embodiment of the present invention. FIG. 11 illustrates REs in which an additional CSI-RS pattern may be actually configured according to the shape of a subframe based on the embodiment described with reference to FIG. 9- (a). In FIG. 11, REs shown in dark gray are REs in which an existing CSI-RS pattern (legacy CSI-RS pattern) may be configured, and REs shown in light gray are REs in which a newly added CSI-RS pattern may be configured. admit. In addition, in FIG. 11, A is a DMRS antenna port {7, 8, 11, 13}, and B are REs used to transmit DMRS on the DMRS antenna port {9, 10, 12, 14}. Vertically hatched sections represent GP and UpPTS regions.

11- (a) shows REs in which an additional CSI-RS pattern may be configured in a general subframe having a general CP. REs in which the additional CSI-RS pattern of FIG. 11- (a) may be configured are the same as REs in which the additional CSI-RS pattern of FIG. 9- (a) may be configured. 11- (b) shows REs in which an additional CSI-RS pattern can be configured in special subframe configuration 3, 4 or 8 with general CP, and FIG. 11- (c) shows special subframe configuration with general CP. Represents REs in which an additional CSI-RS pattern may be configured at 1, 2, 6 or 7. REs in which the additional CSI-RS patterns of FIGS. 11- (b) and 11- (c) may be configured are compared to REs in which the additional CSI-RS patterns of FIGS. 9- (a) may be configured. Partly limited by the REs used for DMRS transmission on the third and fourth OFDM symbols of the slot. 11- (d) shows REs in which an additional CSI-RS pattern can be configured in a special subframe configuration 9 having a general CP. REs in which the additional CSI-RS pattern of FIG. 11- (d) may be configured are the third and fourth slots of the first slot, as compared to REs in which the additional CSI-RS pattern of FIG. 9- (a) may be configured. Partly limited by the REs used for DMRS transmission on the OFDM symbol, the REs on the first and second OFDM symbols of the second slot cannot be used by both the GP and UpPTS regions.

Meanwhile, FIG. 11 shows REs in which an additional CSI-RS pattern may be actually configured according to the shape of a subframe based on the embodiment described in FIG. 9- (a), but embodiments of the present invention are limited thereto. It doesn't happen. That is, in the same manner based on the embodiments described with reference to FIGS. 9- (b) to 9- (d), 10- (a), and 10- (b), additional CSI- according to the subframe type is provided. REs for which the RS pattern may actually be configured may be defined differently.

12 and 13 illustrate a CSI-RS configuration method according to another embodiment of the present invention. FIG. 12 illustrates an example of each CSI-RS pattern configured in REs in which an additional CSI-RS pattern may be configured based on the embodiment described with reference to FIG. 9. FIG. 13 illustrates an example of each CSI-RS pattern configured in REs in which an additional CSI-RS pattern may be configured based on the embodiment described with reference to FIG. 10. 12 and 13, REs shown in dark gray are REs to which an existing CSI-RS pattern (legacy CSI-RS pattern) can be constructed, and REs shown in light gray are to constitute a newly added CSI-RS pattern. REs that can be. In Figures 12 and 13, the number is the index of each CSI-RS pattern. An index of each CSI-RS pattern illustrated in FIGS. 12 and 13 is just an example, and the CSI-RS pattern may be indexed by another method.

12- (a) to 12- (d) show the number of CSI-RS antenna ports in REs to which the additional CSI-RS pattern of FIGS. 9- (a) to 9- (d) may be configured, respectively. An example of each CSI-RS pattern when eight is shown. Each CSI-RS pattern is composed of eight REs. Accordingly, a total of 64 REs in which additional CSI-RS patterns may be configured may be allocated to eight additional CSI-RS patterns. When the number of CSI-RS antenna ports is four, two CSIs in which each CSI-RS pattern composed of eight REs shown in FIGS. 12- (a) to 12- (d) are composed of four REs Can be divided into -RS patterns. Accordingly, when the number of CSI-RS antenna ports is four, a total of 64 REs in which additional CSI-RS patterns may be configured may be allocated to 16 additional CSI-RS patterns. When the number of CSI-RS antenna ports is one or two, each CSI-RS pattern composed of four REs may be divided into two CSI-RS patterns composed of two REs. Accordingly, when the number of CSI-RS antenna ports is one or two, a total of 64 REs in which additional CSI-RS patterns may be configured may be allocated to 32 additional CSI-RS patterns.

13- (a) and 13- (b) show the number of CSI-RS antenna ports in REs to which the additional CSI-RS pattern of FIGS. 10- (a) and 10- (b) can be configured, respectively. An example of each CSI-RS pattern when eight is shown. Each CSI-RS pattern is composed of eight REs, so that a total of 56 REs for which additional CSI-RS patterns can be configured may be allocated to seven additional CSI-RS patterns. When the number of CSI-RS antenna ports is four, two CSIs in which each CSI-RS pattern composed of eight REs shown in FIGS. 13- (a) and 13- (b) are composed of four REs Can be divided into -RS patterns. Accordingly, when the number of CSI-RS antenna ports is four, a total of 56 REs for which additional CSI-RS patterns may be configured may be allocated to 14 additional CSI-RS patterns. When the number of CSI-RS antenna ports is one or two, each CSI-RS pattern composed of four REs may be divided into two CSI-RS patterns composed of two REs. Accordingly, when the number of CSI-RS antenna ports is one or two, a total of 56 REs for which additional CSI-RS patterns may be configured may be allocated to 28 additional CSI-RS patterns, respectively.

14 and 15 illustrate a CSI-RS configuration method according to another embodiment of the present invention. 14 and 15 illustrate an example of each CSI-RS pattern configured in the REs in which additional CSI-RS patterns may be configured, based on the embodiment described with reference to FIG. 12- (a). It is shown in detail according to the number. In FIG. 14 and FIG. 15, REs shown in dark gray are REs to which an existing CSI-RS pattern (legacy CSI-RS pattern) may be configured, and REs shown in light gray are configured to newly add a CSI-RS pattern. REs that can be. In FIG. 14 and FIG. 15, the number is an index of each CSI-RS pattern. The index of each CSI-RS pattern illustrated in FIGS. 14 and 15 is just an example, and the CSI-RS pattern may be indexed by another method.

14- (a) shows an example of a specific CSI-RS pattern when the number of CSI-RS antenna ports is one or two. 14- (b) shows an example of a specific CSI-RS pattern when the number of CSI-RS antenna ports is four. 14- (c) shows an example of a specific CSI-RS pattern when the number of CSI-RS antenna ports is eight. In this case, in FIG. 14, a is CSI-RS antenna port {15} or {15, 16}, b is CSI-RS antenna port {17, 18}, c is CSI-RS antenna port {19, 20}, and d is CSI. -RSs are used to transmit the CSI-RS on the antenna port {19, 20}. That is, CSI-RS through one or two CSI-RS antenna ports, a through four CSI-RS antenna ports, C through the CSI-RS through a and b, eight CSI-RS antenna ports. In the case of CSI-RS, a, b, c and d may be used.

15- (a) to 15- (c) illustrate the existing 32 CSI-RS patterns (when the number of CSI-RS antenna ports is one or two), and FIGS. 14- (a) to FIG. The indexes of the CSI-RS patterns shown in each of 14- (c) are added by 32 respectively.

14 and 15 illustrate specific CSI-RS patterns according to the number of CSI-RS antenna ports based on the embodiment described with reference to FIG. 12- (a), but embodiments of the present invention are limited thereto. It is not. That is, additional CSI-RS patterns may be configured in the same manner based on the embodiments described with reference to FIGS. 12- (b) to 12- (d), 13- (a), and 13- (b). The CSI-RS pattern may be configured differently according to the number of CSI-RS antenna ports in the REs.

Additional CSI-RS patterns according to the number of CSI-RS antenna ports illustrated in FIGS. 14 and 15 may be indicated by Table 7 below.

TABLE 7

Table 7 may be used in addition to Table 1 described above. That is, Table 1 indicates mapping of an existing CSI-RS configuration and a CSI-RS pattern in a subframe having a general CP, and Table 7 shows an additional CSI-RS configuration and a CSI-RS pattern of a subframe having a general CP. You can indicate the mapping.

As described above, the CSI-RS configuration of Table 1 may be indicated by a 5-bit resourceConfig parameter signaled from the RRC layer. The CSI-RS configuration of Table 7 may be indicated in two ways as follows.

1) Table 7 indicating an additional CSI-RS configuration may be indicated in a form defined separately from Table 1 indicating an existing CSI-RS configuration. That is, the 5-bit resourceConfig parameter indicating the additional CSI-RS configuration of Table 7 may be defined separately from the 5-bit resourceConfig parameter indicating the existing CSI-RS configuration of Table 1. The location of the first RE for the first CSI-RS antenna port among the CSI-RS antenna ports is indicated by the resourceConfig parameter, and the positions of the remaining REs for each CSI-RS antenna port may be indicated by Equation 5 described above. . This form corresponds to FIG. 14 and may correspond to Case A in Table 7.

A new 1 bit indicating which CSI-RS configuration is selected between the existing CSI-RS configuration and the additional CSI-RS configuration may be signaled through the RRC layer. If the value of the new 1 bit is 0 (or 1), the existing CSI-RS configuration, that is, Table 1 may be indicated. If the value of the new 1 bit is 1 (or 0), an additional CSI-RS configuration, that is, Table 7 may be indicated. According to the new 1-bit value, whether the CSI-RS configuration indicated by the 5-bit resourceConfig parameter is an existing CSI-RS configuration of Table 1 or an additional CSI-RS configuration separately configured in Table 7 may be determined.

2) Table 7 indicating an additional CSI-RS configuration may be indicated in the form of being incorporated into Table 1 indicating an existing CSI-RS configuration. That is, the additional CSI-RS configuration of Table 7 is not defined separately, but instead, the 5-bit resourceConfig parameter indicating the existing CSI-RS configuration of Table 1 is changed to 6 bits, thereby changing the CSI-RS configuration of Table 1 and Table 7. You can direct them all. Table 1 and Table 7 may be combined. The location of the first RE for the first CSI-RS antenna port among the CSI-RS antenna ports is indicated by the resourceConfig parameter, and the positions of the remaining REs for each CSI-RS antenna port are described above. It may be indicated by the equation (5) described. This form corresponds to FIG. 15 and may correspond to Case B in Table 7.

Table 7 shows that the additional CSI-RS configuration includes both a separately defined form (Case A) and an integrated form of the existing CSI-RS configuration (Case B), but since Case A and Case B are mutually exclusive, Table 7 may include only one of Case A and Case B.

Hereinafter, according to an embodiment of the present invention, a method of maximally doubling the number of CSI-RS patterns configurable in a subframe having an extended CP will be described. As described above, a total of 28 CSI-RS patterns when the number of CSI-RS antenna ports is 1 or 2 in a subframe having an extended CP, and 14 CSI when the number of CSI-RS antenna ports is 4 When the -RS pattern has 8 CSI-RS antenna ports, there are a total of 7 CSI-RS patterns. This may be indicated by a 5-bit resourceConfig parameter signaled via RRC.

According to an embodiment of the present invention, when the number of CSI-RS antenna ports is one or two in a subframe having an extended CP, 36 CSI-RS patterns are added to form a total of 64 CSI-RS patterns. Can be. In addition, when the number of CSI-RS antenna ports is 4 in a subframe having an extended CP, 18 CSI-RS patterns may be added to form a total of 32 CSI-RS patterns. In addition, when the number of CSI-RS antenna ports is 8 in a subframe having a general CP, 9 CSI-RS patterns may be added to form a total of 16 CSI-RS patterns.

16 illustrates a CSI-RS configuration method according to another embodiment of the present invention. FIG. 16 illustrates REs in which an existing CSI-RS pattern may be configured and REs in which an additional CSI-RS pattern may be configured in a subframe having an extended CP. REs shown in dark gray in FIG. 16- (a) are REs to which an existing CSI-RS pattern (legacy CSI-RS pattern) can be constructed. In FIG. 16- (b), REs shown in light gray are newly added. REs in which the CSI-RS pattern may be configured.

Referring to FIG. 16- (b), a CSI-RS pattern may be newly defined for a total of 72 REs in one PRB pair. Therefore, as described above, when the number of CSI-RS antenna ports is one or two, 36 CSI-RS patterns are added, so that when the total of 64 CSI-RS patterns is four and the number of CSI-RS antenna ports is four, A total of 32 CSI-RS patterns may be added by adding 18 CSI-RS patterns, and when the number of CSI-RS antenna ports is 8, 9 CSI-RS patterns may be added to form a total of 16 CSI-RS patterns. .

Referring to FIG. 16- (b), a new addition among all REs (a total of 24 REs with 12 REs for each OFDM symbol) on the first and second OFDM symbols of the first slot in one PRB pair The CSI-RS pattern may be configured. In addition, a newly added CSI-RS pattern among all the REs on the third and fourth OFDM symbols of the first slot (a total of 24 REs with 12 REs for each OFDM symbol) in one PRB pair may be configured. Can be. In addition, a newly added CSI-RS pattern among all the REs on the first and second OFDM symbols of the second slot (total of 24 REs with 12 REs for each OFDM symbol) in one PRB pair may be configured. Can be. In this case, the REs on the second OFDM symbol of the second slot may be used as REs for transmitting only one of the existing CSI-RS or the additional CSI-RS.

Some of the REs in which the additional CSI-RS pattern described in FIG. 16 may be configured are CSI-RSs according to the positions of DMRSs defined differently according to the subframe type (general surf frame and each component of the special subframe). The configuration of the pattern may be limited. That is, even though the REs are defined so that an additional CSI-RS pattern may be configured in FIG. 16, the REs overlapping the REs to which the DMRS is allocated are excluded from the REs configurable for CSI-RS transmission. However, the CSI-RS pattern is not separately defined according to the form of the subframe, and only REs used for DMRS transmission may be excluded from the REs defined so that an additional CSI-RS pattern may be configured.

17 illustrates a CSI-RS configuration method according to another embodiment of the present invention. FIG. 17 illustrates REs in which an additional CSI-RS pattern may be actually configured according to the shape of a subframe based on the embodiment described with reference to FIG. 16. In FIG. 17, REs shown in dark gray are REs that can form an existing CSI-RS pattern (legacy CSI-RS pattern), and REs shown in light gray are REs in which a newly added CSI-RS pattern can be configured. admit. The horizontally hatched portions are REs on the second OFDM symbol of the second slot and are REs in which an existing CSI-RS pattern may be configured or an additional CSI-RS pattern may be configured. In addition, E in FIG. 17 are REs used to transmit DMRS on DMRS antenna ports {7, 8}. Vertically hatched sections represent GP and UpPTS regions.

17- (a) shows REs in which an additional CSI-RS pattern may be configured in a general subframe having an extended CP. 17- (b) shows REs in which an additional CSI-RS pattern may be configured in special subframe configuration 1, 2, 3, 5, or 6 having an extended CP.

18 illustrates a CSI-RS configuration method according to another embodiment of the present invention. FIG. 18 illustrates an example of each CSI-RS pattern configured in REs on which additional CSI-RS patterns may be configured based on the embodiment described with reference to FIG. 16. The REs shown in light gray in FIG. 18 are REs for which a newly added CSI-RS pattern may be configured. In FIG. 18, a number is an index of each CSI-RS pattern. The index of each CSI-RS pattern shown in FIG. 18 is merely an example, and the CSI-RS pattern may be indexed by another method.

FIG. 18 shows an example of each CSI-RS pattern when the number of CSI-RS antenna ports is 8 in REs in which the additional CSI-RS pattern of FIG. 16 may be configured. Each CSI-RS pattern is composed of eight REs, so a total of 72 REs in which additional CSI-RS patterns can be configured may be allocated to nine additional CSI-RS patterns. When the number of CSI-RS antenna ports is four, each CSI-RS pattern composed of eight REs shown in FIG. 18 may be divided into two CSI-RS patterns composed of four REs. Accordingly, when the number of CSI-RS antenna ports is 4, a total of 72 REs for which additional CSI-RS patterns may be configured may be allocated to 18 additional CSI-RS patterns. When the number of CSI-RS antenna ports is one or two, each CSI-RS pattern composed of four REs may be divided into two CSI-RS patterns composed of two REs. Accordingly, when the number of CSI-RS antenna ports is one or two, a total of 72 REs in which additional CSI-RS patterns may be configured may be allocated to 36 additional CSI-RS patterns, respectively.

19 illustrates a CSI-RS configuration method according to another embodiment of the present invention. FIG. 19 illustrates an example of each CSI-RS pattern configured in REs in which an additional CSI-RS pattern may be configured based on the number of CSI-RS antenna ports, based on the embodiment described with reference to FIG. 18. will be. The REs shown in light gray in FIG. 19 are REs for which a newly added CSI-RS pattern may be configured. In FIG. 19, a number is an index of each CSI-RS pattern. The index of each CSI-RS pattern shown in FIG. 19 is merely an example, and the CSI-RS pattern may be indexed by another method.

19- (a) shows an example of a specific CSI-RS pattern when the number of CSI-RS antenna ports is one or two. 19- (b) shows an example of a specific CSI-RS pattern when the number of CSI-RS antenna ports is four. 19- (c) shows an example of a specific CSI-RS pattern when the number of CSI-RS antenna ports is eight. In FIG. 19, a denotes a CSI-RS antenna port {15} or {15, 16}, b denotes a CSI-RS antenna port {17, 18}, c denotes a CSI-RS antenna port {19, 20}, and d denotes a CSI. -RSs are used to transmit the CSI-RS on the antenna port {19, 20}. That is, CSI-RS through one or two CSI-RS antenna ports, a through four CSI-RS antenna ports, C through the CSI-RS through a and b, eight CSI-RS antenna ports. In the case of CSI-RS, a, b, c and d may be used.

Additional CSI-RS patterns according to the number of CSI-RS antenna ports shown in FIG. 19 may be indicated by Table 8. FIG.

Table 8

Table 8 may be used in addition to Table 2 described above. That is, Table 2 indicates mapping of the existing CSI-RS configuration and the CSI-RS pattern in the subframe with the extended CP, Table 8 shows the additional CSI-RS configuration and CSI-RS pattern of the subframe with the extended CP You can indicate the mapping.

As described above, the CSI-RS configuration of Table 2 may be indicated by a 5-bit resourceConfig parameter signaled from the RRC layer. Table 8 indicating additional CSI-RS configuration may be indicated in the form of integration into Table 2 indicating an existing CSI-RS configuration. That is, the additional CSI-RS configuration of Table 8 is not defined separately, but instead the 5-bit resourceConfig parameter indicating the existing CSI-RS configuration of Table 2 is changed to 6 bits, thereby changing the CSI-RS configuration of Table 2 and Table 8. You can direct them all. Tables 2 and 8 can be combined. The location of the first RE for the first CSI-RS antenna port among the CSI-RS antenna ports is indicated by the resourceConfig parameter, and the positions of the remaining REs for each CSI-RS antenna port may be indicated by Equation 5 described above. . This form corresponds to FIG. 19.

20 shows an example of a method of transmitting a reference signal according to an embodiment of the present invention.

Referring to FIG. 20, in step S100, the base station transmits a CSI-RS resource configuration indicator to the terminal. The CSI-RS resource configuration indicator may be used to indicate an existing CSI-RS configuration and / or an additional CSI-RS configuration.

The CSI-RS resource configuration indicator may be 1 bit transmitted through the RRC layer. If the value of the CSI-RS resource configuration indicator is 0 (or 1), the existing CSI-RS configuration of Table 1 may be indicated. If the value of the CSI-RS resource configuration indicator is 1 (or 0), the additional CSI-RS configuration of Table 7 may be indicated. According to the value of the CSI-RS resource configuration indicator, it may be determined whether the CSI-RS configuration indicated by the 5-bit resourceConfig parameter is an existing CSI-RS configuration of Table 1 or an additional CSI-RS configuration separately configured in Table 7.

Alternatively, the CSI-RS resource configuration indicator may be a 6-bit resourceConfig parameter. By changing the existing 5-bit resourceConfig parameter to 6 bits, the existing CSI-RS configuration and additional CSI-RS configuration in Table 1 and Table 7 can be indicated simultaneously in a subframe having a general CP, and having an extended CP Existing CSI-RS configuration and additional CSI-RS configuration in subframes Table 2 and Table 8 may be indicated simultaneously.

In step S110, the base station generates a CSI-RS sequence. The CSI-RS sequence may be generated by Equations 1 to 3 below.

In step S120, the base station modulates the generated CSI-RS sequence according to the CSI-RS pattern of one existing CSI-RS configuration or one additional CSI-RS configuration selected based on the CSI-RS resource configuration indicator. To map to resource elements in the subframe. The modulation symbol may be generated by Equation 4. The CSI-RS sequence may be mapped to a resource element according to the CSI-RS pattern described in FIGS. 9 to 19 according to various embodiments of the present disclosure. In addition, the CSI-RS sequence may be mapped to a resource element based on Table 7 in a subframe having a general CP and Table 8 in a subframe having an extended CP.

In step S130, the base station transmits an OFDM signal generated based on the CSI-RS sequence mapped to the resource element to the terminal.

In step S140, the UE receives an OFDM signal, demodulates it, and performs channel estimation. The procedure for demodulating an OFDM signal may be the reverse of the procedure for generating an OFDM signal. For example, the terminal de-maps the received OFDM signal to resource elements to detect a modulation symbol and detect a CSI-RS sequence from the modulation symbol. The terminal performs channel estimation by comparing the detected CSI-RS sequence with the CSI-RS sequence generated by the terminal itself.

21 is a block diagram of a wireless communication system in which an embodiment of the present invention is implemented.

The base station 800 includes a processor 810, a transmitter 820, and a receiver 830. The processor 810 includes a reference signal generator 811 and a resource mapper 812.

The reference signal generator 811 is configured to generate a CSI-RS sequence. The reference signal sequence may be generated by equations (1) through (3).

The resource mapper 812 modulates the generated CSI-RS sequence according to a CSI-RS pattern of one existing CSI-RS configuration or one additional CSI-RS configuration selected based on the CSI-RS resource configuration indicator. Configured to map to resource elements within a subframe using a symbol. The modulation symbol may be generated by Equation 4. The CSI-RS sequence may be mapped to a resource element according to the CSI-RS pattern described in FIGS. 9 to 19 according to various embodiments of the present disclosure. In addition, the CSI-RS sequence may be mapped to a resource element based on Table 7 in a subframe having a general CP and Table 8 in a subframe having an extended CP.

The transmitter 820 is configured to transmit the OFDM signal generated based on the CSI-RS resource configuration indicator and the CSI-RS sequence mapped to the resource element, to the terminal 900. The CSI-RS resource configuration indicator may be used to indicate an existing CSI-RS configuration and / or an additional CSI-RS configuration. The CSI-RS resource configuration indicator may be 1 bit transmitted through the RRC layer. According to the value of the CSI-RS resource configuration indicator, it may be determined whether the CSI-RS configuration indicated by the 5-bit resourceConfig parameter is an existing CSI-RS configuration of Table 1 or an additional CSI-RS configuration separately configured in Table 7. Alternatively, the CSI-RS resource configuration indicator may be a 6-bit resourceConfig parameter. By changing the existing 5-bit resourceConfig parameter to 6 bits, the existing CSI-RS configuration and additional CSI-RS configuration in Table 1 and Table 7 can be indicated simultaneously in a subframe having a general CP, and having an extended CP Existing CSI-RS configuration and additional CSI-RS configuration in subframes Table 2 and Table 8 may be indicated simultaneously.

The receiver 830 is configured to receive an uplink signal from the terminal 900.

The terminal 900 includes a channel estimator 910, a transmitter 920, and a receiver 930.

The receiver 930 is configured to receive the CSI-RS resource configuration indicator and the OFDM signal from the base station 800.

The channel estimator 910 is configured to demodulate the received OFDM signal to perform channel estimation. The procedure for demodulating an OFDM signal may be the reverse of the procedure for generating an OFDM signal. For example, the channel estimator 910 detects a modulation symbol by demapping the received OFDM signal to resource elements, and detects a CSI-RS sequence from the modulation symbol. The channel estimator 910 performs channel estimation by comparing the detected CSI-RS sequence with the CSI-RS sequence generated by the UE itself.

The transmitter 920 is configured to transmit an uplink signal to the base station 800.

According to an embodiment of the present invention, an additional CSI-RS pattern may be configured using additional RRC signaling or a ResourceConfig parameter in which the number of bits is increased. Existing existing CSI-RS configuration and additional CSI-RS configuration is set the same regardless of each subframe type, and some configured CSI-RS pattern may be excluded according to the shape of each subframe. Accordingly, the number of configurable CSI-RS patterns can be increased up to two times.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims (20)

In the method for transmitting a reference signal by the evolved-NodeB (eNB) in a wireless communication system, The CSI-RS resource configuration indicator corresponding to any one of the existing channel state information (CSI) reference signal (RS) configuration set or an additional CSI-RS configuration set may be configured as a UE. transmitting to equipment; Generating a CSI-RS sequence; Modulating the generated CSI-RS sequence according to the CSI-RS pattern of any one of the existing CSI-RS configuration set or the additional CSI-RS configuration set selected based on the CSI-RS resource configuration indicator; symbol) to map to resource elements in the subframe; And And transmitting an orthogonal frequency division multiplexing (OFDM) signal generated based on the mapped CSI-RS sequence to the terminal. The method of claim 1, The CSI-RS resource configuration indicator is a 1-bit radio resource control (RRC) signaling indicating any one of the existing CSI-RS configuration set or the additional CSI-RS configuration set. The method of claim 2, When the value of the 1 bit is 0, the CSI-RS resource configuration indicator indicates the existing CSI-RS configuration set, And when the value of the 1 bit is 1, the CSI-RS resource configuration indicator indicates the additional CSI-RS configuration set. The method of claim 2, If the 1-bit value is 1, the CSI-RS resource configuration indicator indicates the existing CSI-RS configuration set, And when the value of the 1 bit is 0, the CSI-RS resource configuration indicator indicates the additional CSI-RS configuration set. The method of claim 1, And the CSI-RS resource configuration indicator is a 6-bit resourceConfig parameter indicating one of the CSI-RS patterns. The method of claim 1, The one CSI-RS pattern is configured according to the number of CSI-RS antenna ports. The method of claim 1, The subframe has a normal (cyclic) prefix (CP) or extended (extended) CP. The method of claim 1, When the CSI-RS sequence is mapped according to the CSI-RS pattern of any one of the additional CSI-RS configuration set, Wherein the resource elements are resource elements on first to fourth orthogonal frequency division multiplexing (OFDM) symbols of a first slot and first and second OFDM symbols of a second slot. A method of performing channel estimation by a user equipment (UE) in a wireless communication system, Evolved a CSI-RS resource configuration indicator corresponding to either the existing channel state information (CSI) reference signal (RS) configuration set or an additional CSI-RS configuration set Receiving from NodeB); Receiving an orthogonal frequency division multiplexing (OFDM) signal generated based on a CSI-RS sequence from the base station; And Demodulating the received OFDM signal to perform channel estimation; The CSI-RS sequence is generated according to the CSI-RS pattern of any one of the existing CSI-RS configuration set or the additional CSI-RS configuration set selected based on the CSI-RS resource configuration indicator. And a sequence is mapped to resource elements in a subframe using a modulation symbol. The method of claim 9, The CSI-RS resource configuration indicator is a 1-bit radio resource control (RRC) signaling indicating any one of the existing CSI-RS configuration set or the additional CSI-RS configuration set. The method of claim 10, When the value of the 1 bit is 0, the CSI-RS resource configuration indicator indicates the existing CSI-RS configuration set, And when the value of the 1 bit is 1, the CSI-RS resource configuration indicator indicates the additional CSI-RS configuration set. The method of claim 10, If the 1-bit value is 1, the CSI-RS resource configuration indicator indicates the existing CSI-RS configuration set, And when the value of the 1 bit is 0, the CSI-RS resource configuration indicator indicates the additional CSI-RS configuration set. The method of claim 9, And the CSI-RS resource configuration indicator is a 6-bit resourceConfig parameter indicating one of the CSI-RS patterns. The method of claim 9, The one CSI-RS pattern is configured according to the number of CSI-RS antenna ports. The method of claim 9, The subframe has a normal (cyclic) prefix (CP) or extended (extended) CP. The method of claim 9, When the CSI-RS sequence is mapped according to the CSI-RS pattern of any one of the additional CSI-RS configuration set, Wherein the resource elements are resource elements on first to fourth orthogonal frequency division multiplexing (OFDM) symbols of a first slot and first and second OFDM symbols of a second slot. In a user equipment (UE) in a wireless communication system, CSI-RS resource configuration indicator and CSI-RS sequence corresponding to any one of the existing channel state information (CSI) reference signal configuration set or additional CSI-RS configuration set. A receiver configured to receive an orthogonal frequency division multiplexing (OFDM) signal generated based on the; And A channel estimator configured to demodulate the received OFDM signal to perform channel estimation; The CSI-RS sequence is generated according to the CSI-RS pattern of any one of the existing CSI-RS configuration set or the additional CSI-RS configuration set selected based on the CSI-RS resource configuration indicator. And a sequence is mapped to resource elements in a subframe using a modulation symbol. The method of claim 17, The CSI-RS resource configuration indicator is a terminal characterized in that the 1-bit radio resource control (RRC) signaling indicating either of the existing CSI-RS configuration set or the additional CSI-RS configuration set. The method of claim 17, The CSI-RS resource configuration indicator is a terminal characterized in that the 6-bit resourceConfig parameter indicating the CSI-RS pattern. The method of claim 17, The one CSI-RS pattern is characterized in that configured according to the number of CSI-RS antenna port.

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