TW201547297A - Scheme for transmitting reference signal in wireless communication system - Google Patents

Abstract

Methods, systems, apparatuses, evolved NodeB (eNBs), User Equipment (UE), and chip sets for all of the same, in cellular communication systems are described. One method for a UE includes receiving a Channel State Information Reference Signal (CSI-RS) transmitted by an eNB according to a pattern in a time-frequency resource grid determined based on the transmission scheme of the eNB, measuring the state of the transmission channel using the CSI-RS, generating channel state information based on the measuring, and transmitting the channel state information as feedback. The UE receives a downlink signal including data and a Cell-specific Reference Signal (CRS) from the eNB and estimates the transmission channel using the CRS and then acquires the data using the estimated channel.

Description

Mechanism for transmitting reference signals in a wireless communication system

The present invention relates to a mechanism for transmitting a reference signal in a wireless communication system, and more particularly to a method and apparatus for transmitting a reference signal based on an interference signal in a cellular communication system.

In next generation wireless communication systems (eg, Long Term Evolution-Advanced (LTE-A) systems), cell coverage is relatively small compared to traditional cellular environments. When various cells such as a legacy cell and a femtocell operate in the same environment, a non-uniform cell distribution occurs.

A user equipment (UE) can receive not only a desired signal from a serving cell (also referred to as a "required signal") but also an unwanted signal from another or "interfering" cell. (Also known as "interference signal"). In such an environment, inter-cell interference is the biggest factor that increases packet errors and thus reduces UE performance.

In an LTE wireless communication system, an evolved NodeB (eNB) transmits a reference signal (eg, a Channel State Information-Reference Signal (CSI-RS)) before transmitting the data to the UE to allow the The UE measures the channel quality of the serving cell. In addition, the eNB may utilize CSI Interference Measurement (IM) to allow the UE to measure channel quality in consideration of channels of neighboring cells.

The UE uses the CSI-IM to determine a Channel Quality Indicator (CQI) and transmits feedback of the channel quality information to the eNB. The eNB transmits the data to the UE based on the feedback. In this case, the eNB may also transmit a Cell-specific Reference Signal (CRS) for a specific cell on an Orthogonal Frequency Division Multiplex (OFDM) domain together with the data. The UE can estimate the required channel (ie, the channel of the desired signal) when the UE receives the data.

In order for a next generation UE (eg, a Long Term Evolution Advanced (LTE-A) UE) to most efficiently remove interfering signals from received signals to reduce packet errors of the desired signals, the UE requires information on the transmission mechanism of the interfering signals and Channel information that interferes with the signal. Although the CSI-IM can be used to estimate the transmission mechanism information of the interference signal, this estimation is limited because the CSI-IM reuses the pattern of the CSI-IM that is not suitable for estimating the transmission mechanism.

Therefore, in order to solve the interference problem, a method, apparatus, and system for accurately estimating a transmission mechanism of an interference signal received by a next-generation UE are required.

To overcome the limitations of CSI-IM, an aspect of the present invention provides a new CSI-RS pattern that first considers the transmission mechanism, and provides an estimate of the transmission mechanism information of the interference signal using the provided CSI-RS pattern. The method of maximizing performance. Another aspect of the present invention provides a new RS for estimating transmission mechanism information of an interference signal for use by a next generation UE for removing the interference signal.

In accordance with another aspect of the present invention, the UE can determine accurate channel status information and thereby increase system capacity. According to still another aspect of the present invention, the UE may improve a Space Frequency Block Code (SFBC), SFBC Frequency-Switched Transmit Diversity (SFBC-FSTD), or a cyclic delay. The estimation capability of the transmission mechanism of CDD Spatial Multiplexing (CDD-SM). In this aspect, the UE may cause a false alarm detection error and a miss alarm caused by the interference signal in a transmission mechanism including at least one of SFBC, SFBC-FSTD, and CDD-SM. The miss alarm detection error is minimized. According to another aspect of the present invention, the UE can improve the interference removal capability by accurately estimating the transmission mechanism of the interference signal, and thereby enhance its packet error estimation capability.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the invention, a detailed description of known configurations or functions incorporated herein is not necessary to the ordinary skill in the art and/or In the case where it becomes unclear, a detailed description of the known configuration or function will be omitted. The terms used herein are used and/or defined in consideration of the functions of the present invention, but the terms and specific implementations of the terms may vary depending on the intention or convention of the user or operator. Therefore, the definition of terms should be determined based on the contents of the specification and the knowledge of those of ordinary skill in the art, and should not be construed as limiting the general disclosure or scope of the appended claims.

In the detailed description of the invention, examples of the interpretable meanings of certain terms used in the present invention are provided; however, the terms are not limited to the examples of the understandable meanings provided below.

A base station is a body that communicates with a User Equipment (UE) and may be referred to as a BS, a Node B (NB), an eNode B (eNB), an Access Point (AP), and the like.

The user equipment is an object that communicates with the BS, and may be referred to as a UE, a Mobile Station (MS), a Mobile Equipment (ME), a device, a terminal, and the like.

In the present invention, reference signals (e.g., CSI-RS, CRS, CSI-IM, and Demodulation-Reference Signal (DM-RS)) used in the LTE system, and newly defined reference signals (e.g., "Transmission Mode-Interference Measurement (TM-IM)" and "Channel State Information-Transmission Mode-Interference Measurement (CSI-TM-IM)" signals ).

The reference signal (CRS) for a specific cell refers to a reference signal transmitted from the eNB and is used by the UE to estimate the data receiving channel (H). The CRS has characteristics for a particular cell and is transmitted in all downlink subframes and all frequency resource blocks.

The Channel State Information-Reference Signal (CSI-RS) refers to a reference signal transmitted from the eNB and used by the UE to measure channel state information (CSI) of the serving cell. The CSI-RS is not transmitted in all downlink subframes, but is sparsely transmitted to produce a relatively small overhead compared to the CRS.

A Demodulation Variable Reference Signal (DM-RS) refers to a reference signal transmitted from an eNB and used by a UE to estimate a Physical Downlink Shared Channel (PDSCH). The DM-RS has characteristics for a specific UE and is accordingly transmitted in a resource block allocated for the PDSCH of the UE.

Channel State Information-Interference Measurement (CSI-IM) refers to a reference signal transmitted from an eNB and is used by the UE to take into account interfering signals when measuring channel status information. The CSI-IM is transmitted using the same pattern as the pattern of the CSI-RS. The eNB transmits both CSI-IM and CSI-RS, and can transmit CSI-RS (ie, zero-power CSI-RS) without transmission power to improve channel state information measurement performance of the interfering cell.

According to an aspect of the present invention, a method for a User Equipment (UE) in a cellular communication system is provided, comprising: receiving a channel state information reference signal (CSI) transmitted according to a pattern in a frequency-time resource grid -RS), the pattern is determined by an evolved NodeB (eNB) based on a transmission mechanism; using the CSI-RS to measure a state of a transmission channel with the eNB; generating channel state information based on the measurement; Transmitting the channel state information as feedback to the eNB; receiving a reference signal (CRS) for the specific cell from the eNB; estimating the transmission channel using the CRS; and acquiring using the estimated channel The data transmitted on the transmission channel.

According to another aspect of the present invention, a method for an evolved NodeB (eNB) in a cellular communication system is provided, comprising: channel state information reference signal (CSI-RS) according to a pattern in a time-frequency resource grid Transmitting to a User Equipment (UE), the pattern is determined based on a transmission mechanism of the eNB; receiving channel state information of the UE generated by using the CSI-RS; and transmitting information and targeting a specific cell The downlink signal of the reference signal (CRS).

According to still another aspect of the present invention, a user equipment (UE) for use in a cellular communication system includes: a controller that receives a channel state information reference signal transmitted according to a pattern in a time-frequency resource grid (CSI-RS), the pattern is determined based on an evolutionary NodeB (eNB) transmission mechanism; the CSI-RS is used to measure a state of a transmission channel with the eNB; and a channel state is generated based on the measurement Transmitting the channel status information as feedback to the eNB; receiving a reference signal (CRS) for the specific cell from the eNB; estimating the transmission channel using the CRS; and acquiring the estimated channel using the And transmitting, by the controller, the CSI-RS, transmitting the channel status information, and receiving the CRS and the transmission channel.

According to still another aspect of the present invention, an evolved NodeB (eNB) for use in a cellular communication system is provided, comprising: a controller, the channel state information reference signal (CSI- according to a pattern in a time-frequency resource grid) RS) is transmitted to a User Equipment (UE), the pattern is determined based on a transmission mechanism of the eNB, receiving channel state information of the UE generated by using the CSI-RS, and transmitting information and specific a downlink signal of a reference signal (CRS) of the cell; and a transceiver that transmits the CSI-RS under control of the controller, receives the channel status information, and transmits the downlink signal.

According to still another aspect of the present invention, a chip set for a User Equipment (UE) in a cellular communication system is provided for receiving a transmission according to a pattern in a frequency-time resource grid a channel state information reference signal (CSI-RS), the pattern being determined by an evolved NodeB (eNB) based on a transmission mechanism; using the CSI-RS to measure a state of a transmission channel with the eNB; based on the amount Generating channel state information; transmitting the channel state information as feedback to the eNB; receiving a reference signal (CRS) for the specific cell from the eNB; estimating the transmission channel by using the CRS; The estimation channel acquires data transmitted on the transmission channel.

According to still another aspect of the present invention, a chip set for an evolved NodeB (eNB) in a cellular communication system is provided for: channel state information reference signal (CSI) according to a pattern in a time-frequency resource grid -RS) transmitted to a User Equipment (UE), the pattern being determined based on a transmission mechanism of the eNB; receiving channel state information of the UE generated by using the CSI-RS; and transmitting information and targeting A downlink signal of a reference signal (CRS) of a specific cell.

First, a mechanism for defining a CSI-RS pattern in consideration of a transmission mechanism of the eNB (for example, a transmission diversity transmission scheme using a plurality of antennas) is explained.

FIG. 1 illustrates an example of a system in which a UE receives signals from a serving cell and an interfering cell.

The UE 120 not only receives the desired signal 122 from the eNB 100 (i.e., the eNB of the serving cell), but also receives the interference signal 124 from the eNB 110 (i.e., the eNB of the interfering cell).

Figure 2 illustrates an example of an interference signal transmitted from an interfering cell.

As shown in FIG. 2, in an LTE system, CRSs 202 and 204 and a physical downlink shared channel (PDSCH) 200 corresponding to a data channel may be in a frequency-time resource grid (ie, resources having a frequency axis and a time axis). Transfer on the grid).

When transmitting data via the PDSCH 200, the eNB may utilize various transport mechanisms depending on the channel environment with the UE. Specifically, a Multiple-Input Multiple-Output (MIMO)-based eNB using multiple antennas may utilize a transmission diversity technique and a Spatial Multiplexing (SM) technology. For example, in an LTE system that utilizes two transmit antennas, a spatial frequency block code (SFBC) based transmit diversity technique or a cyclic delay diversity (CDD) based SM technique (ie, CDD-SM) may be utilized. Techniques such as SFBC or CDD-SM are implemented by two adjacent (or adjacent) subcarriers 210 (i.e., consecutive subcarriers on the frequency axis) as shown in the example of FIG. ......................... Equation (1)

Equation (1) represents a signal transmitted to antennas 及0 and 1 using two adjacent carriers 210 (e.g., resource regions defined by subcarriers 0 and 1) in an SFBC transmission mechanism. Based on equation (1), the signal and Transmitted to antennas 埠0 and 1 on subcarrier 0, and the signal and The subcarriers 1 are respectively transmitted to the antennas 及0 and 1.

Each of equations (2) and (3) represents a signal transmitted using two adjacent carriers 0 and 1 by the CDD-SM transmission mechanism. ........................... Equation (2) ......................... Equation (3)

Equation (2) shows an example of a CDD-SM transmission mechanism in which signals are transmitted on the carrier 0 to the antennas 及0 and 1, and equation (3) shows the CDD-SM in which the signals are transmitted on the carrier 1 to the antennas 及0 and 1. An example of a transport mechanism. Signal 1/2 ( + ) and 1/2 ( - ) transmitted to carrier 埠0 and 1 on carrier 0, respectively, and signal 1/2 ( + ) and 1/2 ( + ) is transmitted on carrier 1 to antennas 及0 and 1.

An LTE system utilizing four transmit antennas has expanded transmit diversity and spatial multiplexing. The transmit diversity technique may combine SFBC with frequency switched transmit diversity (FSTD), for example, using four antennas 、0, 1, 2, and four adjacent carriers (eg, carriers 0, 1, 2, and 3).

For example, equations (4)(a) and (4)(b) represent signals when carriers 0, 1, 2, and 3 and four transmit antennas 、0, 1, 2, and 3 are utilized in the transmit diversity technique. . ...................... Equation (4)(a) ...................... Equation (4)(b)

Equations (1) to (4) (b) represent signals in a transmission mechanism for transmitting signals via adjacent carriers using a plurality of antennas. In order to accurately measure channel state information and transmission mechanism information of a received signal, it is necessary to estimate the signal received via adjacent (continuous) carriers on the frequency axis.

3 illustrates an example of CSI-RS patterns of two CSI-RSs in a time-frequency resource grid of a Resource Block (RB) composed of resource elements (REs) in an LTE system. The resource elements are defined by fourteen symbols on the time axis and twelve subcarriers on the frequency axis.

In FIG. 3, CRS #0 signal 300 is used for CRS 埠 0, CRS #1 signal 302 is used for CRS 埠 1, and CSI-RS symbol 310 is used for two CSI-RS 埠. The CSI-RS pattern may be defined by a location (or distribution) of one or more resources used to transmit the CSI-RS symbols.

4 illustrates an example of four CSI-RS 埠 CSI-RS patterns in a time-frequency resource grid of one RB in an LTE system.

In FIG. 4, a CRS #0 signal 400, a CRS #1 signal 402, and CSI-RS symbols 410 and 412 for four CSI-RSs are displayed.

Referring to the CSI-RS patterns 310, 410, and 412 shown in FIG. 3 and FIG. 4 (ie, the arrangement pattern of CSI-RS symbols), it may be noted that the CSI-RS symbols are in the signal subcarrier of the time-frequency resource grid. Spread in the direction of the time axis. That is, the CSI-RSs 310, 410, and 412 of FIGS. 3 and 4 are transmitted by two symbols adjacent (continuous) on the time axis in one subcarrier. The CSI-RS patterns of Figures 3 and 4 are opposite to the following characteristics in the transmission mechanism using transmission diversity: the transmitted signals are arranged to spread (or continuously) on the frequency axis at the same time (i.e., the same symbol). .

Therefore, the present invention provides a method for maximizing channel channel information measurement performance and transmission mechanism information estimation performance by defining a CSI-RS pattern in consideration of a transmission mechanism of a transmitter. In particular, the present invention provides a method of transmitting two or more CSI-RS symbols associated with each other using two or more consecutive subcarriers on a frequency axis. 5 and 6 illustrate a CSI-RS pattern designed in consideration of a transmission mechanism in an LTE system.

5 illustrates another example of CSI-RS patterns of two CSI-RSs in a time-frequency resource grid of one RB in an LTE system, the one RB being fourteen symbols and frequencies on the time axis The twelve subcarriers on the axis are defined.

In FIG. 5, a CRS #0 signal 500, a CRS #1 signal 502, and a CSI-RS symbol 510 for two CSI-RSs are transmitted as shown.

6 illustrates another example of CSI-RS patterns of four CSI-RSs in a time-frequency resource grid of one RB in an LTE system.

In FIG. 6, a CRS #0 signal 600, a CRS #1 signal 602, and CSI-RS symbols 610 and 612 for four CSI-RSs are transmitted as shown. The CSI-RS patterns 510, 610, and 612 shown in FIGS. 5 and 6 are spread in the frequency axis direction of the time-frequency resource grid but occupy the same time resource (ie, symbol). That is, the CSI-RSs 510, 610, and 612 of FIGS. 5 and 6 utilize two adjacent (continuous) frequency subcarriers but are transmitted in only one time resource (ie, the same symbol). The CSI-RS patterns of FIGS. 5 and 6 correspond to the following characteristics in a transmission mechanism using transmission diversity: two CSI-RS symbols associated with each other (eg, symbols transmitted via adjacent antennas) are successively in the same time Arranged on the frequency axis (ie, in the same symbol on consecutive subcarriers).

The eNB according to the present invention can transmit the CSI-RS by using the patterns shown in FIG. 5 and FIG. 6, and the UE can measure the channel status information by using the CSI-RS and transmit the feedback to the eNB. For the correspondence of the characteristics shown in FIG. 5 and FIG. 6, the CSI-RS pattern defined by considering the transmission mechanism of the transmitter can maximize the performance by improving the channel state information measurement and transmission mechanism information estimation.

Figure 7 illustrates an example of the operation of an eNB and a UE in a wireless communication system utilizing a patterned CSI-RS in accordance with the present invention.

The process of FIG. 7 can be divided into two parts, a CSI feedback part 710 and a data transmission part 720. In the feedback portion, the UE 702 provides feedback channel status information using the reference signals transmitted from the eNB 700 in step 712, while in the data transmission portion 720, the eNB 700 utilizes channel status information that the UE is fed back in the first portion 710. Transfer data. The operation of Figure 7 will be explained in more detail below.

In step 712, the eNB 700 transmits a pilot signal (i.e., a reference signal) used by the UE 702 to measure the channel status. The reference signal may for example be a CSI-RS or a CSI-IM. More specifically, the UE 702 measures the channel status of the serving cell using the CSI-RS transmitted by the Serving eNB 700, and measures the interfering cell using the CSI-IM transmitted by the Serving eNB and/or other interfering eNBs. Channel status. In step 714, the UE 702 measures the serving cell channel status using the CSI-RS received from the Serving eNB 700. In step 716, the UE 702 measures the interfering cell channel status using the CSI-IM received by the Servo eNB and/or other interfering eNBs. In step 718, the UE 702 generates Serving Cell Channel Status Information (CSI) based on the measurements in steps 714 and 716 and transmits the Servo Cell Channel Status Information (CSI) to the Serving eNB 700.

The CSI fed back to the eNB 700 in step 718 may include a channel quality indicator (CQI), an indicator indicating a modulation and coding scheme (MCS), a Rank Indicator (RI), and/or a precoding matrix indicator. (Precoding Matrix Indicator, PMI).

Using the CSI received in step 718, the eNB 700 can determine the transmission mechanism of the UE 702. For example, in an LTE system, a CRS-based transmission mode may correspond to TM 1 to TM 6. In step 722, the eNB 700 transmits the CRS while transmitting the data to the UE 702 via the PDSCH.

In step 724, the UE 702 utilizes the received CRS to estimate the data transmission channel and utilize the estimated channel to receive the data. The estimation of the channel by the UE may mean an estimation of the channel function H of the transmission channel. For example, the received signal y can be expressed as y = Hx + n, where H refers to the channel function, x refers to the transmitted signal, and n refers to the noise (including the interfering signal).

In FIG. 7, the CRS-RS may have the CSI-RS pattern shown in FIG. 5 or 6. For example, it is contemplated that the eNB 700 transmits two CSI-RS symbols via two antennas by two consecutive subcarriers in the same time resource. Since the transmission mechanism is employed on two consecutive subcarriers in the same time resource, the advantageous effects of the CSI-RS pattern application according to the present invention can be obtained.

Similarly, the CSI-IM can be transmitted by the same pattern as the pattern of the CSI-RS.

In FIG. 7, the Serving eNB may configure a zero-power CSI-RS for its CSI-IM in a pattern as shown in FIG. 5 or FIG. 6, and the interfering eNB may configure a non-zero power CSI for its CSI-IM in the same pattern. RS. Since the UE 702 receives the CSI-IM overlapping with the zero-power CSI-RS resources from the Serving eNB from the interfering eNB, the beneficial effects of the CSI-RS pattern application according to the present invention can be obtained. In the present invention, CSI-IM埠 can be understood as a transmission of at least a CSI-IM symbol.

In FIG. 8, a CRS #0 signal 800, a CRS #1 signal 802, and CSI-RS symbols 810 and 812 for four CSI-IM ports are transmitted as shown. Referring to the CSI-IM patterns 810 and 812 shown in FIG. 8, the CSI-IM symbols are spread in the frequency axis direction while remaining in the same time resource (ie, symbol). That is, the CSI-IM signal can be transmitted by the same pattern as that shown for the CSI-RS in FIG. Alternatively, the eNB of the neighboring cell may transmit a zero-power CSI-RS in the resource for CSI-IM signal transmission.

The next generation UE (e.g., UE supporting LTE-A) may remove the interference signal from the received signal to reduce the packet error of the desired signal. To remove the interference signal, the UE may utilize transmission mechanism information of the interference signal and channel status information. 9 and 11 illustrate an example of a method of implementing an operation of estimating transmission mechanism information of an interference signal by a UE to remove the interference signal in accordance with the present invention.

The present invention provides a new reference signal (hereinafter, referred to as "TM-IM") for estimating information on an interference signal transmission mechanism. The new reference signal TM-IM (Transmission Mode Interference Measurement) is a reference signal that assists in performing blind detection of the transmission mechanism information of the cell that produces the strongest interference. The TM-IM may also be referred to as channel state information-transmission mode-interference measurement (CSI-TM-IM). The UE may estimate the transmission mechanism information of the interference signal by using the TM-IM transmitted by the eNB 900, and may use the estimated transmission mechanism information of the interference signal to remove the interference signal from the received signal to further reduce the received data. The packet is incorrect.

9 illustrates an example of operation of an eNB and a UE in a wireless communication system employing TM-IM, which utilizes a pattern of CSI-RS, in accordance with the present invention.

As in Fig. 7, the process in Fig. 9 is divided into two parts: a CSI feedback section 910 and a data transmission section 930. In the first portion 910, the UE 902 feeds back channel state information to the eNB 900 using the reference signal transmitted by the eNB 900, and in the second portion 930, the eNB 900 utilizes channel state information fed back by the UE 902 in the first portion 910. Transmit downlink data. The operation of Figure 9 will be explained in more detail below.

In step 912, the eNB 900 transmits an indicator signal (i.e., a reference signal) used by the UE 902 to measure the channel status. The reference signal may for example be a CSI-RS or a CSI-IM.

The CSI-RS or CSI-IM may have the CSI-RS pattern shown in FIG. 5 or FIG. 6. For example, the eNB may transmit a diversity transmission mechanism to perform transmission by two or more CSI-RSs, in which the CSI transmitted by the two or more CSI-RSs is- Two symbols in an RS symbol (or CSI-IM symbol) may be transmitted by two consecutive subcarriers in the same time resource. For example, the transmission diversity transmission mechanism adopted by the eNB may be SFBC, SFBC-FSTD or CDD-SM.

In step 914, the UE 902 measures the channel status of the serving cell (i.e., the Serving eNB) using the CSI-RS transmitted by the eNB 900 in step 912. In step 916, the UE 902 measures the channel status of the interfering cell (ie, the interfering eNB) using the CSI-IM transmitted by the eNB 900.

Unlike step 710 of FIG. 7, as indicated by the dashed box of step 918, the UE 902 can estimate the transmission mechanism information of the interfering cell based on the CSI-IM. In FIG. 9, the Serving eNB may configure a zero-power CSI-RS for its CSI-IM in a pattern as shown in FIG. 5 or FIG. 6, and the interfering eNB may configure a non-zero-power CSI for its CSI-IM in the same pattern. -RS. Since the UE 902 receives the CSI-IM overlapping with the zero-power CSI-RS resource from the serving eNB from the interfering eNB, the UE 902 has a high probability to estimate the transmission mechanism information of the interference signal by using the CSI-IM. Such transmission mechanism information may include, for example, transmission mode (TM), PMI, RI, and MCS indicating modulation mechanism and modulation level.

The UE 902 generates channel state information (of the serving cell) based on the measurement result in step 920 and feeds the CSI back to the eNB 900. The channel status information transmitted to the eNB 900 may include at least one of CQI, PMI, and RI.

In step 932, the eNB 900 determines the transmission mechanism using the channel status information and then transmits the CRS and TM-IM while transmitting the data to the UE 902 via the PDSCH. Similarly, the TM-IM can be transmitted from the Serving eNB and/or the interfering eNB by the same pattern as the CSI-RS pattern.

In step 934, the UE 902 estimates the data transmission channel using the CRS and receives the data using the estimated channel. The UE 902 can estimate the channel using the channel function H of the transmission channel. At the same time, the UE 902 can use the TM-IM to estimate the transmission mechanism information of the interference signal, and use the estimated transmission mechanism information to remove the interference signal from the received signal and receive the data. For example, the transmission mechanism information of the interference signal estimated by the UE may be an interference signal parameter, such as the transmission mode (TM), RI, PMI or MCS calculated in step 918.

In FIG. 9, the Serving eNB may configure a zero-power CSI-RS for its TM-IM in a pattern as shown in FIG. 5 or FIG. 6, and the interfering eNB may configure a non-zero power CSI for its TM-IM in the same pattern. RS. Since the UE 902 receives the TM-IM overlapping with the zero-power CSI-RS resource from the serving eNB from the interfering eNB, the UE 902 has a high probability to estimate the transmission mechanism information of the interference signal by using the CSI-IM.

10 illustrates an example of a TM-IM pattern of four TM-IMs in a time-frequency resource grid of one RB in an LTE system according to the present invention, the one RB being represented by fourteen symbols on the time axis and Twelve subcarriers on the frequency axis are defined.

In FIG. 10, a CRS #0 signal 1000, a CRS #1 signal 1002, and TM-IM symbols 1010 and 1012 for four TM-IM ports are transmitted. Referring to the TM-IM patterns 1010 and 1012 shown in FIG. 10, the TM-IM symbols are spread in the frequency axis direction in the same time resource. That is, the TM-IM signal can be transmitted by the same pattern as the pattern of the CSI-RS. Alternatively, the eNB of the neighboring cell may transmit a zero power CSI-RS in the resource for TM-IM signal transmission.

11 illustrates an example of operation of an eNB and a UE in a CSI-TM-IM utilizing a CSI-RS in a wireless communication system employing CSI-TM-IM in accordance with the present invention.

As described above, the present invention provides a new reference signal (hereinafter, referred to as "CSI-TM-IM") for estimating channel state information and information of an interference signal transmission mechanism. The new reference signal CSI-TM-IM (Channel Status Information - Transmission Mode - Interference Measurement) is a reference signal that assists in performing blind detection of the transmission mechanism information of the interfering cell and helps to measure channel status information. CSI-TM-IM can also be referred to as CSI-RSTM (Channel Status Information - Reference Signal Transmission Mode). The UE may estimate the transmission mechanism information of the interference signal or measure the channel status information by using the CSI-TM-IM transmitted by the eNB. The UE may further reduce the packet error when receiving the data based on the estimated transmission mechanism information of the interference signal, and further reduce the packet error when receiving the data, and may generate a feedback based on the measured channel status information. Accurate channel state transmission mechanism to receive data.

The process of FIG. 11 is divided into two parts: a CSI feedback section 1110 and a data transmission section 1130. The UE 1102 transmits channel state information using the reference signal transmitted by the eNB 1100 in the feedback portion 1110, and the eNB 1100 transmits the downlink data using the channel state information in the data transmission portion 1130. The operation of Figure 11 will be explained in more detail below.

The eNB 1100 transmits a pilot signal (i.e., a reference signal) used by the UE 1102 to measure the channel status in step 1112. The reference signal may for example be a CSI-RS or a CSI-IM.

The CSI-RS may have a CSI-RS pattern as shown in FIG. 5 or FIG. 6. Similarly, the CSI-IM can be transmitted by the same pattern as the pattern of the CSI-RS.

In step 1114, the UE 1102 measures the channel state information of the serving cell (ie, the serving eNB) using the CSI-RS transmitted by the eNB 1100. In step 1116, the UE 1102 measures channel state information of the interfering cell (ie, the interfering eNB) using the CSI-IM transmitted by the eNB 1100 and the interfering eNB.

Unlike step 710 of FIG. 7, as indicated by the dashed box of step 1118, the UE 1102 can estimate the transmission mechanism information of the interfering cell based on the CSI-IM. In FIG. 11, the Serving eNB may configure a zero-power CSI-RS for its CSI-IM in a pattern as shown in FIG. 5 or FIG. 6, and the interfering eNB may configure a non-zero power CSI for its CSI-IM in the same pattern. RS. Since the UE 1102 receives the CSI-IM overlapping with the zero-power CSI-RS resource from the serving eNB from the interfering eNB, the UE 1102 has a high probability to estimate the transmission mechanism information of the interference signal by using the CSI-IM. The transmission mechanism information may include, for example, a transmission mode (TM), a PMI, an RI, and an MCS indicating a modulation mechanism and a modulation level.

In step 1120, the UE 1102 generates channel state information (of the serving cell) based on the measurement result and transmits the CSI to the eNB 1100. The channel status information transmitted to the eNB 1100 may include at least one of CQI, PMI, and RI.

In step 1132, the eNB 1100 determines the transmission mechanism using the channel status information and transmits the CRS and CSI-TM-IM while transmitting the data to the UE 1102 via the PDSCH. Similarly, CSI-TM-IM can be transmitted by the same pattern as the patterns shown in FIGS. 5 and 6.

In step 1134, the UE 1102 estimates the data transmission channel using the CRS and then receives the data using the estimated channel. The UE 1102 can estimate the channel using the channel function H. In step 1136, the UE 1102 also uses the CSI-TM-IM to estimate the transmission mechanism information of the interference signal, and measures the channel status information for transmission re-feedback. The UE 1102 uses the transmission mechanism information from step 1118 to remove the interference signal from the received signal. For example, the transmission mechanism information of the interference signal may include interference signal parameters such as transmission mode (TM), RI, PMI or MCS. In addition, CSI-TM-IM can be used to estimate CSI as a feedback CSI. In other words, one CSI-TM-IM can be utilized for both the interference transmission mechanism estimation and the CSI estimation.

12 illustrates an example of four CSI-TM-IM埠 CSI-TM-IMs in a time-frequency resource grid of one RB in an LTE system according to the present invention, the one RB being fourteen on the time axis The symbols are defined by twelve subcarriers on the frequency axis.

In FIG. 12, a CRS #0 signal 1200, a CRS #1 signal 1202, and CSI-TM-IM symbols 1210 and 1212 for four CSI-TM-IM ports are transmitted. Referring to the CSI-TM-IM patterns 1210 and 1212 shown in FIG. 12, the CSI-TM-IM symbols are spread in the frequency axis direction in the same time resource. That is, the CSI-TM-IM signal can be transmitted by the same pattern as the pattern of the CSI-RS. Alternatively, the eNB of the neighboring cell may transmit a zero-power CSI-RS in the resource for CSI-TM-IM signal transmission.

13 illustrates an example of a method in which an eNB transmits information or CSI process information for identifying a reference signal to a UE in accordance with the present invention.

As shown in FIG. 13, the eNB 1300 may transmit reference signal identification information or CSI process information to the UE 1302 in step 1310 before the operation of transmitting the reference signal and channel state information feedback as described in FIGS. 7-12.

The reference signal identification information corresponds to indicating to the UE at least one of a reference signal for channel measurement (ie, CSI-RS, CSI-IM, TM-IM, CSI-TM-IM, and zero-power CSI-RS) Information, the reference signal is transmitted based on the pattern according to the invention. The reference signal identification information may be transmitted by radio resource control (RRC) layer communication or by downlink control information (DCI) of the physical layer.

The CSI process information (eg, for an LTE system) corresponds to information indicating that it is selected from reference signals for channel measurement (ie, CSI-RS, CSI-RS, CSI-IM, TM-IM, CSI-TM-IM) And at least one reference signal of the zero-power CSI-RS) and a location of a resource to be used for transmitting the reference signal, the reference signal being transmitted based on the pattern according to the present invention. Preferably, the CSI process information may consist of a piece of information including a plurality of pieces of information about 3 to 4 reference signals in a group. The CSI process information may be transmitted by the RRC layer transmission or by the physical layer DCI.

Figure 14 is a block diagram of an eNB device in accordance with the present invention.

The eNB device 1400 can include a transceiver 1410 (eg, a radio frequency (RF) wafer) that can communicate with the UE via a signal and a controller 1420 (eg, a modem chip) for controlling the transceiver 1410. Transceiver 1410 and controller 1420 can also be implemented as one component (eg, a chipset).

The controller 1420 is a component for implementing the reference signal according to the present invention and the data transmission method performed by the eNB. That is, all operations of the above eNB can be understood as being implemented by the controller 1420.

Figure 15 is a block diagram of a UE device in accordance with the present invention.

The UE device 1500 can include a transceiver 1510 that can communicate with an eNB or another UE via a signal and a controller 1520 for controlling the transceiver 1520. The transceiver 1510 and the controller 1520 can also be implemented as one component.

The controller 1520 is a component for implementing a transmission/reception method of the UE according to the present invention. That is, all operations of the above UE can be understood as being implemented by the controller 1520.

The system configuration shown in Figures 1 through 15, an example of a time-frequency resource grid, an example of a method, and a block diagram of the apparatus are not intended to limit the scope of the invention. That is, all of the descriptions, time-frequency resource grid arrangements, configurations, or operational steps associated with FIGS. 1 through 15 are not to be understood as essential to the practice of the invention, and without departing from the scope of the invention. The invention may be practiced using only some of the elements described.

The above operations can be implemented by providing a memory device storing the corresponding code to any constituent unit of the communication system entity, the base station, or the terminal. That is, the communication system entity, the terminal, the base station, or the controller of the terminal or the base station reads and executes the code stored in the memory device by using a processor or a central processing unit (CPU). Do the above.

Various component units, modules, etc. may be combined by hardware circuits (eg, logic circuits based on complementary metal oxide semiconductors), firmware, software, and/or hardware and firmware, and/or embedded in machine readable media. The software in the implementation. As an example, various electronic configurations and methods can be performed using, for example, transistors, logic gates, and application specific integrated circuits (ASICs).

Various component units, modules, etc. may be combined by hardware circuits (eg, logic circuits based on complementary metal oxide semiconductors), firmware, software, and/or hardware and firmware, and/or embedded in machine readable media. The software in the implementation. As an example, various electronic configurations and methods can be performed using, for example, transistors, logic gates, and application specific integrated circuits (ASICs).

100‧‧‧Serv eNB
110‧‧‧Interfering eNB
120‧‧‧UE
122‧‧‧Required signal
124‧‧‧Interference signal
200‧‧‧ Physical Downlink Shared Channel (PDSCH)
202‧‧‧Reference signal for a specific cell (CRS#0 signal)
204‧‧‧Reference signal for a specific cell (CRS#1 signal)
210‧‧‧Subcarrier
300‧‧‧CRS#0 signal
302‧‧‧CRS#1 signal
310‧‧‧CSI-RS symbol
400‧‧‧CRS#0 signal
402‧‧‧CRS#1 signal
410‧‧‧CSI-RS symbol
412‧‧‧CSI-RS symbol
500‧‧‧CRS#0 signal
502‧‧‧CRS#1 signal
510‧‧‧CSI-RS symbol
600‧‧‧CRS#0 signal
602‧‧‧CRS#1 signal
610‧‧‧CSI-RS symbol
612‧‧‧CSI-RS symbol
700‧‧‧eNB
702‧‧‧UE
710‧‧‧CSI feedback part
720‧‧‧Data transmission section
712-718, 722-724‧‧‧ steps
800‧‧‧CRS#0 signal
802‧‧‧CRS#1 signal
810‧‧‧CSI-RS symbol
812‧‧‧CSI-RS symbol
900‧‧‧eNB
902‧‧‧UE
910‧‧‧CSI feedback part
930‧‧‧Data transmission section
912-920, 932-934‧‧‧ steps
1000‧‧‧CRS#0 signal
1002‧‧‧CRS#1 signal
1010‧‧‧TM-IM symbol
1012‧‧‧TM-IM symbol
1100‧‧‧eNB
1102‧‧‧UE
1110‧‧‧CSI feedback part
1130‧‧‧Data transmission section
1112～1120, 1132～1136‧‧‧ steps
1200‧‧‧CRS#0 signal
1202‧‧‧CRS#1 signal
1210‧‧‧CSI-TM-IM symbol
1212‧‧‧CSI-TM-IM symbol
1300‧‧‧eNB
1302‧‧‧UE
1310‧‧‧Steps
1400‧‧‧eNB device
1410‧‧‧ transceiver
1420‧‧‧ Controller
1500‧‧‧UE device
1510‧‧‧ transceiver
1520‧‧‧ Controller

The above and other aspects, features, and advantages of the present invention will become more apparent from the detailed description of the appended claims. Figure 2 illustrates an example of an interference signal transmitted from an interfering cell. Figure 3 illustrates an example of a pattern that utilizes two CSI-RS 埠 in an LTE system. Figure 4 illustrates an example of a pattern that utilizes four CSI-RS 埠 in an LTE system. Figure 5 illustrates an example of a pattern that utilizes two CSI-RS 埠 in an LTE system. Figure 6 illustrates an example of a pattern that utilizes four CSI-RS 埠 in an LTE system. Figure 7 illustrates an example of the operation of an eNB and a UE in a wireless communication system utilizing a patterned CSI-RS in accordance with the present invention. Figure 8 illustrates an example of a pattern of four CSI-IM 埠 in an LTE system in accordance with the present invention. Figure 9 illustrates an example of operation of an eNB and a UE and an interference signal transmission mechanism reference signal in a wireless communication system using a patterned CSI-RS in accordance with the present invention. Figure 10 illustrates an example of a pattern of four TM-IMs in an LTE system in accordance with the present invention. Figure 11 illustrates an example of operation of an eNB and a UE and a channel state information-interference signal transmission mechanism reference signal in a wireless communication system using a patterned CSI-RS in accordance with the present invention. Figure 12 illustrates an example of a pattern of four CSI-TM-IM 埠 in an LTE system in accordance with the present invention. 13 illustrates an example of a method by which an eNB transmits information for identifying a reference signal and CSI process information to a UE according to the present invention. Figure 14 is a block diagram of an eNB device in accordance with the present invention. Figure 15 is a block diagram of a UE device in accordance with the present invention.

500‧‧‧CRS#0 signal

502‧‧‧CRS#1 signal

510‧‧‧CSI-RS symbol

Claims (26)

A method for a user equipment (UE) in a cellular communication system, comprising: receiving a channel state information reference signal (CSI-RS) transmitted according to a pattern in a frequency-time resource grid, the pattern being based on Determining a transmission mechanism of the evolved NodeB (eNB); measuring the state of the transmission channel with the eNB by using the CSI-RS; generating channel state information based on the measurement; and transmitting the channel state information as feedback Receiving, by the eNB, a reference signal (CRS) for a specific cell; estimating the transmission channel by using the CRS; and acquiring data transmitted on the transmission channel by using the estimated channel. The method of claim 1, wherein the UE operates in a transmit diversity transmission mechanism, and the pattern corresponds to two consecutive subcarriers on a frequency axis by the time-frequency resource grid To transmit a pattern of two consecutive CSI-RS symbols. The method of claim 2, wherein the two consecutive CSI-RS symbols correspond to two CSIs transmitted by two CSI-RSs used in the transmission diversity transmission mechanism. RS symbol. The method of claim 1, further comprising: receiving a CSI interference measurement (CSI-IM) transmitted according to the pattern. The method of claim 1, further comprising: receiving a first reference signal, wherein the first reference signal is transmission mechanism information transmitted according to the pattern and used to estimate an interference signal; and utilizing the A reference signal estimates the transmission mechanism information of the interference signal, and uses the estimated transmission mechanism information of the interference signal to remove the interference signal from a downlink signal. The method of claim 1, further comprising: receiving a second reference signal, the second reference signal being transmitted according to the pattern and used for measuring channel state information of the interference signal and estimating the Information about the transmission mechanism of the interference signal; estimating the transmission mechanism information of the interference signal by using the second reference signal, and using the estimated transmission mechanism information of the interference signal to remove the downlink signal from the downlink signal Interference signal; generating channel state information of the UE by using the estimated transmission mechanism information of the interference signal; and transmitting the generated channel state information as re-feedback. The method of claim 1, wherein the spatial frequency block code (SFBC), the SFBC-frequency switched transmission diversity (FSTD), and the cyclic delay diversity-space multiplexing (CDD-SM) are used. A transmission mechanism of the one transmits the CSI-RS. The method of claim 1, wherein the channel status information comprises a channel quality indicator (CQI), a level indicator (RI), and a precoding matrix indicator indicating a modulation and coding scheme (MCS). At least one of (PMI). The method of claim 5, wherein the transmission mechanism information of the interference signal comprises at least one of the following parameters of the interference signal: a transmission mode (TM), a precoding matrix indicator (PMI), level indicator (RI), and modulation and coding mechanism (MCS) indicating the modulation mechanism and modulation level. The method of claim 1, further comprising, before the step of receiving the CSI-RS, receiving: information indicating at least one of: CSI-RS, zero-power CSI-RS, CSI interference Measurement (CSI-IM), a first reference signal for estimating transmission mechanism information of the interference signal, and a second reference for measuring channel state information of the interference signal and estimating transmission mechanism information of the interference signal The signal is transmitted according to the pattern by radio resource control (RRC) layer communication or transmitted as downlink control information (DCI). The method of claim 1, further comprising, before the step of receiving the CSI-RS: receiving information indicating a CSI process related to at least one of: CSI-RS, zero-power CSI -RS, CSI interference measurement (CSI-IM), a first reference signal for estimating transmission mechanism information of the interference signal, and channel state information for measuring the interference signal and a transmission mechanism for estimating the interference signal A second reference signal of information transmitted by radio resource control (RRC) layer communication according to the pattern or transmitted as downlink control information (DCI). A method for an evolved NodeB (eNB) in a cellular communication system, comprising: transmitting a channel state information reference signal (CSI-RS) to a user equipment (UE) according to a pattern in a time-frequency resource grid, The pattern is determined based on a transmission mechanism of the eNB; receiving channel state information of the UE generated by using the CSI-RS; and transmitting a downlink including a data and a reference signal (CRS) for a specific cell signal. The method of claim 12, wherein the eNB operates in a transmit diversity transmission mechanism, and the pattern corresponds to two consecutive subcarriers on a frequency axis by the time-frequency resource grid To transmit a pattern of two consecutive CSI-RS symbols. The method of claim 13, wherein the two consecutive CSI-RS symbols correspond to two CSIs transmitted by two CSI-RSs used in the transmission diversity transmission mechanism. RS symbol. The method of claim 12, further comprising: transmitting a CSI interference measurement (CSI-IM) according to the pattern. The method of claim 12, further comprising: transmitting a first reference signal according to the pattern, the first reference signal being used by the UE to estimate transmission mechanism information of the interference signal. The method of claim 12, further comprising: transmitting a second reference signal according to the pattern, the second reference signal being used by the UE to measure channel state information of the interference signal and estimating the Information about the transmission mechanism of the interference signal; and receiving channel state information of the UE generated based on the transmission mechanism information of the interference signal, where the transmission mechanism information of the interference signal is by using the second reference signal Estimate. The method of claim 12, wherein the spatial frequency block code (SFBC), the SFBC-frequency switched transmission diversity (FSTD), and the cyclic delay diversity-space multiplexing (CDD-SM) are used. A transmission mechanism of the one transmits the CSI-RS. The method of claim 12, wherein the channel status information comprises a channel quality indicator (CQI), a level indicator (RI), and a precoding matrix indicator indicating a modulation and coding scheme (MCS). At least one of (PMI). The method of claim 16, wherein the transmission mechanism information of the interference signal comprises at least one of the following parameters of the interference signal: a transmission mode (TM), a precoding matrix indicator (PMI), level indicator (RI), and modulation and coding mechanism (MCS) indicating the modulation mechanism and modulation level. The method of claim 12, further comprising, before the step of transmitting the CSI-RS, transmitting: information indicating at least one of: CSI-RS, zero-power CSI-RS, CSI interference Measurement (CSI-IM), a first reference signal for estimating transmission mechanism information of the interference signal, and a second reference for measuring channel state information of the interference signal and estimating transmission mechanism information of the interference signal The signal is transmitted according to the pattern by radio resource control (RRC) layer communication or transmitted as downlink control information (DCI). The method of claim 12, further comprising, before the step of transmitting the CSI-RS: transmitting information indicating a CSI process related to at least one of: CSI-RS, zero-power CSI -RS, CSI interference measurement (CSI-IM), a first reference signal for estimating transmission mechanism information of the interference signal, and channel state information for measuring the interference signal and a transmission mechanism for estimating the interference signal A second reference signal of information transmitted by radio resource control (RRC) layer communication according to the pattern or transmitted as downlink control information (DCI). A user equipment (UE) for use in a cellular communication system, comprising: a controller that receives a channel state information reference signal (CSI-RS) transmitted according to a pattern in a time-frequency resource grid, the pattern is Determining based on an evolved NodeB (eNB) transmission mechanism; using the CSI-RS to measure a state of a transmission channel with the eNB; generating channel state information based on the measurement; using the channel state information as feedback Transmitting to the eNB; receiving a reference signal (CRS) for a specific cell from the eNB; estimating the transmission channel by using the CRS; and acquiring data transmitted on the transmission channel by using the estimated channel And a transceiver that receives the CSI-RS under control of the controller, transmits the channel status information, and receives the CRS and the transmission channel. An evolved NodeB (eNB) for use in a cellular communication system, comprising: a controller for transmitting a channel state information reference signal (CSI-RS) to a user equipment (UE) according to a pattern in a time-frequency resource grid Determining, according to a transmission mechanism of the eNB, receiving channel state information of the UE generated by using the CSI-RS, and transmitting a downlink including a data and a reference signal (CRS) for a specific cell And a transceiver that transmits the CSI-RS under control of the controller, receives the channel status information, and transmits the downlink signal. A chip set for a user equipment (UE) in a cellular communication system for: receiving a channel state information reference signal (CSI-RS) transmitted according to a pattern in a frequency-time resource grid, the pattern Determined by the evolved NodeB (eNB) based on the transmission mechanism; using the CSI-RS to measure the state of the transmission channel with the eNB; generating channel state information based on the measurement; using the channel state information as Retrieving transmission to the eNB; receiving a reference signal (CRS) for the specific cell from the eNB; estimating the transmission channel using the CRS; and acquiring the transmission on the transmission channel using the estimated channel data. A chip set for an evolved NodeB (eNB) in a cellular communication system, for: transmitting a channel state information reference signal (CSI-RS) to a user equipment according to a pattern in a time-frequency resource grid (UE The pattern is determined based on a transmission mechanism of the eNB; receiving channel state information of the UE generated by using the CSI-RS; and transmitting a downlink including a reference signal (CRS) for a specific cell Link signal.