KR101599851B1 - CoMP Method and apparatus for transmitting precoding matrix index in wireless communication system applied CoMP scheme - Google Patents

Abstract

Hereinafter, a method of transmitting a precoding matrix index in a CoMP communication system is disclosed. The terminal receives signals through the same band from the base stations included in the CoMP set, operating in the associated processing mode, respectively. The UE selects the first precoding matrices corresponding to the base stations included in the CoMP set using these signals, and determines a second precoding matrix by combining these first precoding matrices. The terminal then transmits an index corresponding to the second precoding matrix to the serving base station among the base stations. Where each of the first precoding matrices may correspond to column vectors of a second precoding matrix.

CoMP, joint processing, PMI

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for transmitting a precoding matrix index in a wireless communication system to which a CoMP technique is applied,

The present invention relates to a wireless communication system, and more particularly, to a wireless communication system in which a CoMP technique is applied to a wireless communication system operating in a joint processing mode, For example.

Recently, a multiple input multiple output (MIMO) system has attracted attention as a broadband wireless mobile communication technology. A MIMO system refers to a system that increases data communication efficiency by using a plurality of antennas. The MIMO system can be divided into a spatial multiplexing scheme and a spatial diversity scheme depending on whether the same data is transmitted or not.

Spatial multiplexing refers to a method of transmitting data at high speed without increasing the bandwidth of the system by simultaneously transmitting different data through a plurality of transmission antennas. The spatial diversity scheme refers to a scheme in which transmission diversity can be achieved by transmitting the same data in a plurality of transmission antennas. One example of such a space diversity technique is space time channel coding.

In addition, the MIMO technique can be divided into an open loop method and a closed loop method depending on whether feedback of channel information from a receiving side to a transmitting side is performed. In the open-loop method, information is transmitted in parallel at the transmitting end. In the receiving end, a blast (BLAST) capable of detecting signals by repeatedly using ZF (Zero Forcing) and MMSE (Minimum Mean Square Error) And a space-time trellis code (STTC) scheme that can obtain transmission diversity and coding gain using a space region. And a closed antenna scheme is a TxAA (Transmit Antenna Array) scheme.

1 is a diagram conceptually showing Coordinated Multi-Point (CoMP) techniques applied in a wireless communication system in a multi-cell environment.

Referring to FIG. 1, intra-base stations 110 and 120 and inter-base station 130 exist in a multi-cell environment. In an LTE (Long Term Evolution) system, an intra base station is composed of several cells (or sectors). The cells belonging to the base station to which the specific terminal belongs are related to the specific terminal and the intra base stations 110 and 120. That is, the cells belonging to the same base station as the cell to which the terminal belongs are the cells corresponding to the intra base stations 110 and 120, and the cells belonging to the other base stations are the cells corresponding to the inter base station 130.

In this manner, cells based on the same base station as a specific UE transmit and receive information (for example, data and channel state information (CSI)) through the x2 interface, while cells based on other base stations Cell information can be exchanged through the backhaul 140 or the like. 1, a single-cell MIMO user 150 in a single cell communicates with one serving base station in one cell (sector), and a multi-cell MIMO user 160 located at a cell boundary communicates with multiple cells May communicate with multiple serving base stations.

Coordinated Multi-Point (CoMP) scheme (hereinafter referred to as CoMP scheme) is a system for improving the throughput of a user at a cell boundary by applying improved MIMO transmission in a multi-cell environment. CoMP technique is applied to a wireless communication system, inter-cell interference can be reduced in a multi-cell environment, and a UE can receive data jointly from a multi-cell base station . In addition, each base station can simultaneously support one or more MSs MS1, MS2,... MSK using the same radio frequency resource, thereby improving the performance of the system. Further, the base station may perform a space division multiple access (SDMA) method based on the channel state information between the base station and the terminal.

The operation mode of the CoMP technique can be divided into a cooperative MIMO joint processing mode and a coordinated scheduling / beamforming (CS / CB) mode through data sharing.

In the CoMP technique, a serving BS and one or more neighbor BSs are connected to a scheduler through a backbone network. The scheduler can operate based on feedback of channel information related to channel states between each of the MSs MS1, MS2, ..., MSK measured by the BSs BS1, BS2, ... BSM through the backbone network. For example, the scheduler schedules information for cooperative MIMO operations for a serving base station and one or more cooperative base stations. That is, the scheduler directly performs an instruction for cooperative MIMO operation to each base station.

A terminal of a wireless communication system operating in a closed loop measures channel quality information (CQI) for a data transmission channel with a base station and also calculates a precoding matrix index , And PMI) to the base station and transmit it to the base station. In addition, in the wireless communication system using the CoMP technique, the UE transmits channel quality information and precoding matrix indexes corresponding to the base stations included in the CoMP set to the serving base station, thereby providing a more efficient federated processing mode.

In this manner, in the joint processing mode, two precoding matrix index transmissions of the UE can be considered. First, the UE may select precoding matrix indexes corresponding to the base stations included in the CoMP set and transmit the precoding matrix indexes to the serving BSs individually. Second, the terminal may send one combined PMI corresponding to the base stations included in the CoMP set to the serving base station.

However, in the current LTE (Long Term Evolution) standard, there is no description about how a terminal receiving data through the same frequency band from base stations included in a CoMP set selects and transmits a combined precoding matrix index based on a certain criterion. Therefore, a combined precoding matrix to be selected and transmitted by the UE in the joint processing mode is defined and an embodiment using the combined precoding matrix is described below.

Hereinafter, a method for selecting and transmitting a joint precoding matrix index (Joint PMI) for BSs included in a CoMP set in which a UE operates in a joint processing mode in a CoMP communication system operating in a closed loop, and a method Device.

According to an aspect of the present invention, there is provided a method for transmitting a precoding matrix index of a terminal in a Coordinated Multi-Point (CoMP) communication system, the method comprising: Selecting precoding matrices corresponding to each of the base stations using the signals, selecting one of the precoding matrices corresponding to each of the precoding matrices, Coding matrix, and transmitting an index corresponding to the second precoding matrix to a serving base station among the base stations.

Wherein the rank of the second precoding matrix corresponds to a rank higher than the rank of the first precoding matrices, and preferably the column vectors of the second precoding matrix correspond to the first precoding matrices.

More preferably, the method further comprises transmitting column indexes corresponding to each of the base stations in the second precoding matrix to the serving base station.

Further comprising transmitting a Rank Indicator (RI) corresponding to the second precoding matrix to the serving base station, wherein the index corresponding to the second precoding matrix and the rank indicator are one And is included in an indicator of "

According to another aspect of the present invention, there is provided a CoMP communication system including a Coordination Multi-Point (CoMP) set operating in a joint processing mode, Signals, a first precoding matrix corresponding to each of the base stations is selected using the signals, and a second precoding matrix is generated by combining each of the first precoding matrices, A processor for determining a precoding matrix, and a transmission module for transmitting an index corresponding to the second precoding matrix to a serving base station among the base stations.

Wherein the rank of the second precoding matrix corresponds to a rank higher than the rank of the first precoding matrices, and preferably the column vectors of the second precoding matrix correspond to the first precoding matrices.

More preferably, the processor generates column indexes corresponding to each of the base stations in the second precoding matrix, and the transmitting module is operable, together with the index of the second precoding matrix, And transmits indexes (stream indexes) to the serving base station.

The processor generates a Rank Indicator (RI) corresponding to the second precoding matrix, and the transmitting module transmits the rank indicator to the serving base station together with the index corresponding to the second precoding matrix do. More preferably, the index corresponding to the upper rank precoding matrix and the rank indicator are included in one indicator and transmitted.

It is possible to reduce the amount of feedback information that a UE transmits to a serving base station in a CoMP wireless communication system operating in a closed loop, You can expect.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The detailed description set forth below in conjunction with the appended drawings is intended to illustrate exemplary embodiments of the invention and is not intended to represent the only embodiments in which the invention may be practiced. The following detailed description includes specific details for a better understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without these specific details. For example, in the following description, certain terms are mainly described, but they need not be limited to these terms, and they may have the same meaning when they are referred to as arbitrary terms. Further, the same or similar elements throughout the present specification will be described using the same reference numerals.

Also, the terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings, and the inventor is not limited to the concept of terms in order to describe his invention in the best way. It should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention based on the principle that it can be properly defined.

In the present invention, a cell or a sector means a space controlled by a base station. For convenience of explanation, it is assumed that one cell or sector is controlled by one base station. However, the present invention is not limited to this, and there may be a case where a plurality of cells or sectors controlled by one base station exist .

In the present invention, a CoMP set refers to a set of a Serving eNB operating in a CoMP mode and one or more neighboring eNBs in a wireless communication system.

와 같이 표현할 수 있으며, 여기서 채널 행렬 H 는

×

행렬이고,

은 수 신 안테나의 수를 의미하며,

는 송신 안테나의 수를 의미한다.Also, in the present invention, a rank means a maximum number that can transmit different information in a given channel. This is defined as the minimum number of independent rows or columns in the channel matrix. This is done formally

, Where the channel matrix H can be expressed as

×

Matrix,

Is the number of receive antennas,

Is the number of transmit antennas.

와 같이 표현할 수 있다.Further, in the present invention, a stream refers to each of different information sent using a multi-antenna technique, and may be referred to as a "layer ". Then the number of streams can not be greater than the maximum number of ranks that can send different information. This is done formally

Can be expressed as

As described above, the cooperative processing mode, which is one of the operation modes of the CoMP scheme, is a scheme in which the serving base station and one or more neighbor base stations included in the CoMP set transmit data to the mobile station through the same band And the cooperative processing mode is a scheme starting from the concept of converting a signal regarded as interference in the terminal's position, that is, signals inputted from neighboring base stations into a data transmission signal. In the case of the joint processing mode, the data transmitted from the base stations included in the CoMP set to the mobile station and the channel quality information and the precoding matrix index transmitted from the mobile station as feedback information are transmitted to the base stations included in the CoMP set, Are shared via a backhaul link between them.

On the other hand, since the terminal receives data from the base stations included in the CoMP set, but the frequency band for transmitting data in the cooperative processing mode is the same, it can be seen that the terminal receives data from one transmitting point. That is, when considering each of the base stations as an antenna, it can be seen that data is received through a plurality of channels through a combined channel. Thus, rather than transmitting a precoding matrix index for individual channels as feedback information, it is possible to reduce the overhead in feedback between the terminal and the base stations by transmitting one combined precoding matrix index, or a more accurate precoding matrix This is how you can select an index.

The above-described combination precoding matrix index can be implemented as the following example.

First, a terminal selects one or more precoding matrices with respect to a channel with each base station, determines a combination having the best performance when combining precoding matrices with respect to each base station, Coding matrix indexes. This method may differ from the precoding matrices measured independently for the channels and the precoding matrix for each base station in the combined precoding matrix for the joint processing mode.

Second, each base station that performs joint processing is regarded as a combined transmit antenna, and a corresponding precoding matrix is selected. For example, two base stations that transmit data using four transmit antennas of one rank are regarded as one base station that transmits data using eight transmit antennas, and a precoding matrix corresponding thereto is selected, .

Finally, the MS combines the precoding matrices of each base station selected by the MS to construct a codebook of an upper rank, i.e., an upper rank precoding matrix, and transmit the codebook. This method can be selected when selecting a codebook of an upper rank can achieve better performance, in particular, as compared to combining subordinate precoding matrices. In this case, rank indication (RI) information may be further transmitted. Hereinafter, the final method will be described in detail with reference to Table 1 below.

Table 1 is a codebook for the precoding matrix disclosed in 3GPP TS 36.211, an LTE standard document. Particularly, Table 1 is a codebook for two antenna ports.

First, one serving base station and one neighbor base station constitute a CoMP set and operate in a joint processing mode. The mobile station is located at the cell boundary of the serving base station and receives data from both the serving base station and the neighbor base station through the same frequency band I suppose. It is also assumed that one serving base station and one adjacent base station transmit data to rank 1.

In this case, the UE selects one of precoding matrices having a layer index, that is, a rank index of 1 for each base station. If the UE selects a precoding matrix index 0 for the serving base station, When the matrix index 1 is selected, the combination of the precoding matrix index 0 and the precoding matrix index 1 corresponds to the precoding matrix index 1 of rank 2. In this case, the terminal may configure a precoding matrix of a lower rank as a precoding matrix corresponding to an upper rank. Herein, the precoding matrix of each base station is composed of a column vector of an upper rank precoding matrix, but the present invention is not limited thereto. That is, the selected combined precoding matrix may be a simple combination of precoding matrices for each base station in consideration of the overall performance, and a new precoding matrix other than the precoding matrix may be selected.

In such a case, the UE transmits to the serving base station, with the index of the upper rank precoding matrix, a rank indicator including information on the rank change of the upper rank precoding matrix and a column index of the column rank of the rank rank Can be transmitted.

In the above example, the upper rank precoding matrix is assumed to be rank 2, but it may be configured as a rank 3 or higher precoding matrix as shown in Table 2 below.

이며, I 는 4X4 크기의 단위 행렬이다.Table 2 is a codebook for the precoding matrix when there are four antenna ports disclosed in the LTE standard document 3GPP TS 36.211. In particular,

And I is a unit matrix of 4X4 size.

Referring to Table 2, one combined precoding matrix index with rank 4 can be determined for four base stations operating at rank one. Also, even when the serving base station operating in rank 2 and the neighboring base station operating in rank 2 are included in the CoMP set, it is possible to determine one higher rank precoding matrix as the rank 4 precoding matrix index. Further, even when the serving base station operating in rank 2 and the neighbor base station operating in rank 1 are included in the CoMP set, one higher rank precoding matrix may be determined as the rank 3 precoding matrix index.

In such a case as well, the UE can transmit a rank indicator including information on the rank change along with the index of the upper rank precoding matrix and a stream index related to a column vector corresponding to each base station.

In addition, it is possible to reduce the amount of information to be set in advance for the stream index and fed back. For example, if 1 bit information is specified for the stream index of rank 2 and the information is 0, the first base station matches the first column of the corresponding precoding matrix, the second base station matches the second column, The opposite can be defined as the opposite. In this case, instead of transmitting the stream indexes related to the corresponding column vectors for each base station, it is possible to reduce the overhead due to the feedback information by transmitting only the predetermined information about the correspondence between the stream index and the base station.

Also, the transmission periods of the rank indicator and the upper rank precoding matrix index may be the same or may be otherwise configured. When the transmission periods of the rank indicator and the upper rank precoding matrix index are the same, the rank indicator and the upper rank precoding matrix index may be composed of different information or expressed as one indicator. For example, in the case of using the above-mentioned Table 2, the rank indicator is represented by 2 bits in total from rank 1 to rank 4, and the codebook index can be represented by 4 bits from 0 to 15 in total. In this case, information on a rank indicator and an upper rank precoding matrix index may be respectively defined, or may be represented by information on a rank indicator and an upper rank precoding matrix index combination as one indicator defined by 6 bits.

2 is a conceptual diagram of a wireless communication system according to an embodiment of the present invention.

Referring to FIG. 2, a user equipment (UE) 200 receives information on neighboring base stations included in the CoMP set from the serving base station A 201. In this embodiment, it is assumed that the neighbor base station B 202 and the neighbor base station C 203 are provided as CoMP sets together with the serving base station A 201.

Since the terminal 200 receives data from the base stations included in the CoMP set, but the frequency band for receiving the data in the cooperative processing mode is the same, the terminal 200 can receive data from one transmission point . That is, the set of the serving base station A 201, the neighbor base station B 202 and the neighbor base station C 203 can be regarded as one transmission point.

In general, the UE 200 transmits the channel quality information and the precoding matrix index corresponding to the respective base stations 201 to 203 as feedback information for the joint processing mode to the serving base station. That is, channel quality information and a precoding matrix index corresponding to the channel 204 between the serving base station A 201 and the terminal 200, a channel corresponding to the channel 205 between the adjacent base station B 202 and the terminal 200, Quality information, a precoding matrix index, and channel quality information and a precoding matrix index corresponding to the channel 206 between the serving base station C 203 and the UE 200, respectively, and transmits the measured channel quality information and the precoding matrix index to the serving base station A 201.

At this time, in the present invention, as a feedback information, the terminal 200 transmits a combined precoding matrix index instead of transmitting a precoding matrix index to individual channels to the serving base station A 201.

Also, in the joint processing mode, the combination of channels between the base stations 201 to 203 and the terminal 200 rather than each of the channels between the base stations 201 to 203 and the terminal 200 reflects a data transmission path in a substantially associated processing mode Therefore, the combined channel quality information for one signal combined with the reference signals received through the same band can be generated.

3 is a flowchart illustrating a method of transmitting a precoding matrix index of a UE according to an embodiment of the present invention. Particularly, in the embodiment of the present invention, a method of constructing a codebook of an upper rank among the above-described combination precoding matrix indexes will be described. The CoMP set also comprises a serving base station and one or more neighbor base stations, and may operate in a federated processing mode.

Referring to FIG. 3, in step 301, the UE receives a signal for selecting a precoding matrix index from the Node Bs included in the CoMP set. The signal is preferably a reference signal or a pilot signal.

Subsequently, in step 302, the terminal selects a precoding matrix corresponding to each of the base stations included in the CoMP set. In this embodiment, for convenience of description, the precoding matrix selected in step 302 is expressed by the low rank precoding matrices W _LR (1), W _LR (2), ..., W _LR ( n ) a represents a precoding matrix W by _LR. Where n is the number of base stations included in the CoMP set.

In step 303, the UE selects one upper rank precoding matrix W _HR , and in step 304, the channel quality information corresponding to the combined precoding matrix W _LR and the upper rank precoding matrix W _HR ). & _Lt ; / RTI > If it is effective to communicate using the one higher rank precoding matrix W _HR , the UE, in step 305, may serve as an index corresponding to the upper rank precoding matrix W _HR as feedback information for the joint processing mode In step 306, stream indexes of the upper rank precoding matrix W _HR corresponding to each of the base stations included in the CoMP set, that is, the precoding matrix corresponding to the base station, are transmitted to the upper rank precoding And transmits to the serving base station information about which column vector among the column vectors of the matrix W _HR .

In step 307, the terminal transmits a rank indicator corresponding to the rank change of the precoding matrix, for example, a rank indicator that has changed from rank 1 to rank 2, to the serving base station. The above-described steps 305 to 307 may be simultaneously transmitted to the serving base station in one step. Further, indexes, stream indexes, and rank indicators corresponding to the upper rank precoding matrix W _HR may be transmitted in one indicator and transmitted to the serving base station in various other combinations It will be apparent to those skilled in the art that the present invention is not limited thereto.

On the other hand, if it is determined in step 304 that it is effective to communicate using the combined precoding matrix W _LR , the terminal transmits indices of the lower rank precoding matrix to the serving base station in step 308.

Hereinafter, a method of setting a CoMP set in a wireless communication system to which a CoMP technique is applied will be described as an embodiment utilizing the above-described upper rank precoding matrix ( W _HR ) transmission method.

In this embodiment, the 'associated information' refers to interference level information of neighboring base stations in communication between the terminals and the serving base station.

Also, when selecting a neighboring base station included in the CoMP set, there may be a scheme based on information measured by a user equipment (UE) and a method of selecting the serving base station itself without exchanging information with the mobile station. The present embodiment relates to a method of selecting an adjacent base station included in a CoMP set based on information measured by a terminal.

4 is a flowchart illustrating a method of setting a CoMP set according to an embodiment of the present invention.

First, the UEs must have a list of neighbor BSs. To do so, the UEs may receive a list of neighbor BSs from the serving BS or may form a list directly by measuring the neighbor BSs. The UEs then perform measurements based on the neighbor cell list. That is, the UEs measure the associated information such as the interference level for neighbor cells. The measured values for this association information may include one or more of the values described in Table 3 below.

Referring to FIG. 4, in step 401, the UE reports association information necessary for configuring a CoMP set operating in a federated processing mode to a serving base station. The association information may include one or more of the measurement values for the neighbor base station and the base station ID (or cell ID) of the neighbor base station.

In step 402, the serving base station selects one or more neighbor base stations included in the CoMP set according to preset conditions using the association information and the base station ID received in step 401, and in step 403, To the terminal. That is, the serving base station transmits the base station IDs of the selected neighbor base stations to the mobile station in step 402 so that the mobile station can recognize which neighbor base stations are included in the CoMP set.

The UEs receive the reference signal from the base stations included in the CoMP set, and each UE measures channel quality information (CQI) for the channels between the corresponding UE and the base stations included in the CoMP set To the serving base station. More preferably, in the joint processing mode, since the UE receives the reference signals received through the same band, the combined channel quality information for one combined signal of the reference signals may be measured and transmitted to the serving BS.

Also, each of the UEs transmits the low rank precoding matrices W _LR (1), W _LR (2), ..., W _LR (2), ..., W _LR ( n )) are selected and combined. Here, the combined low-rank precoding matrix is represented by W _LR . In addition, the UE selects one upper rank precoding matrix W _HR and transmits the channel quality information corresponding to the combined precoding matrix W _LR and the channel quality information corresponding to the one rank higher precoding matrix W _HR Compare the quality information.

If it is effective to communicate using the one higher rank precoding matrix W _HR , then each of the terminals is assigned an index of the upper rank precoding matrix W _HR in step 405, an index of the upper rank precoding matrix W _HR in each of the base stations included in the CoMP set To the serving base station, a rank indicator corresponding to the stream indexes of the corresponding upper rank precoding matrix W _HR and the rank change of the precoding matrix.

In step 406, the serving base station, which has received the upper rank precoding matrix ( W _HR ) indexes from the UEs, performs a first selection process. That is, the serving base station transmits an upper rank precoding matrix W _HR ) And an upper rank precoding matrix ( W _HR ) index to be transmitted to the adjacent base station using the interference level information when the higher rank precoding matrix is applied.

On the other hand, in the case of the link information received in the CoMP set configuration in step 401, the serving base station does not accurately reflect the interference level and the like which change with time. Accordingly, the UEs periodically or non-periodically or in response to a request from the serving base station transmit association information such as an interference level to the serving base station in step 407, and the receiving base station updates the association information received in the CoMP set configuration .

Subsequently, in step 408, the serving base station transmits to each neighbor base station included in the CoMP set the index, the stream index, and the rank indicator of the selected upper rank precoding matrix in the first selection process of step 406. In this case, it is preferable to transmit the linkage information updated in step 405 and the combined channel quality information measured in step 404 together.

The neighbor base station performs a second selection process of determining a precoding matrix index to be actually used by using the selected upper rank precoding matrix indices and the updated association information.

5 is a block diagram of a terminal device according to an embodiment of the present invention.

5, the terminal device includes a receiving module 510, a processor 520, and a transmitting module 530. Particularly, the processor 520 includes a precoding matrix index (PMI) ) Selection module 540, and a channel quality information generation module 550. [

The receiving module 510 may receive information on the base stations included in the CoMP set in addition to the general data transmitted from the base station. In particular, the receiving module 510 receives signals from the serving base station and one or more neighbor base stations included in the Coordinated Multi-Point (CoMP) set operating in the joint processing mode via the same band.

The processor 520 controls the overall operation of the terminal device. In particular, the precoding matrix index selection module 540 included in the processor 520 selects a precoding matrix index corresponding to the base station, ( W _LR (1), W _LR (2), ..., W ) corresponding to channels between a terminal and a plurality of base stations through which data is received through the same band, _LR ( n )) and combines them. Here, the combined low-rank precoding matrix is represented by W _LR .

Also, the precoding matrix index selection module 540 selects one upper rank precoding matrix W _HR , and _outputs the channel quality information corresponding to the combined precoding matrix W _LR and the one rank rank precoding And compares the channel quality information corresponding to the matrix W _HR . If it is effective to communicate using the one higher rank precoding matrix W _HR , the precoding matrix index selection module 540 selects the upper rank precoding matrix W _HR as feedback information for the federated processing mode Select.

More specifically, the precoding matrix index selection module 540 included in the processor 520 selects the upper rank precoding matrix corresponding to each of the base stations included in the CoMP set, corresponding to the upper rank precoding matrix W _HR , ( W _HR ) and a rank indicator according to the rank change of the precoding matrix.

The channel quality information measurement module 550 measures channel quality information using the reference signal received by the reception module 510. In particular, in the joint processing mode, the channel quality information generation module 550 measures combined channel quality information for one signal in which a plurality of reference signals are combined.

The transmitting module 530 may transmit the precoding matrix index and the channel quality information to the base station. If the wireless communication system operates in a joint processing mode, the precoding matrix index selection module 540 may select the upper rank precoding matrix ( W _HR ) index, stream indexes associated therewith, and a rank indicator to the serving base station. In particular, in the joint processing mode, the transmitting module 530 preferably transmits the combined channel quality information measured by the channel quality information measuring module 550 to the serving BS.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The foregoing description of the preferred embodiments of the invention disclosed herein has been presented to enable any person skilled in the art to make and use the present invention. While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. For example, those skilled in the art can utilize each of the configurations described in the above-described embodiments in a manner of mutually combining them.

Accordingly, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Although the channel quality information transmission method and the apparatus therefor are applied to the 3GPP LTE system in the wireless communication system to which the CoMP scheme is applied, the present invention is applicable to other various mobile communication systems It is possible to apply it to the system.

FIG. 1 conceptually illustrates Coordinated Multi-Point (CoMP) techniques applied in a wireless communication system in a multi-cell environment,

2 is a conceptual diagram of a wireless communication system according to an embodiment of the present invention,

3 is a flowchart illustrating a method of transmitting a precoding matrix index of a UE according to an embodiment of the present invention;

4 is a flowchart illustrating a method of setting a CoMP set according to an embodiment of the present invention,

5 is a block diagram of a terminal device according to an embodiment of the present invention.

Claims (12)

A method for transmitting a precoding matrix index of a terminal in a Coordinated Multi-Point (CoMP) communication system, Receiving signals from the base stations included in the CoMP set, operating in a joint processing mode, via the same band, respectively; Selecting first precoding matrices corresponding to each of the base stations using the signals; Generating a second precoding matrix in which the precoding matrices are combined; And And transmitting an index corresponding to the second precoding matrix to a serving BS among the BSs, The rank of the second precoding matrix is The first precoding matrix having a rank higher than the rank of the first precoding matrices, A method of transmitting a precoding matrix index of a terminal. delete The method according to claim 1, The column vectors of the second precoding matrix Corresponding to the first precoding matrices, A method of transmitting a precoding matrix index of a terminal. The method according to claim 1, Further comprising transmitting column indexes corresponding to each of the base stations in the second precoding matrix to the serving base station. A method of transmitting a precoding matrix index of a terminal. The method according to claim 1, And transmitting a Rank Indicator (RI) corresponding to the second precoding matrix to the serving base station. A method of transmitting a precoding matrix index of a terminal. 6. The method of claim 5, The index corresponding to the second precoding matrix and the rank indicator And is included in one indicator and transmitted, A method of transmitting a precoding matrix index of a terminal. A receiving module for receiving signals from base stations included in a Coordinated Multi-Point (CoMP) set, each operating in a joint processing mode, through the same band; A processor for selecting first precoding matrices corresponding to each of the base stations using the signals and combining the first precoding matrices to determine a second precoding matrix; And And a transmission module for transmitting an index corresponding to the second precoding matrix to a serving BS among the BSs, The rank of the second precoding matrix is The first precoding matrix having a rank higher than the rank of the first precoding matrices, A terminal device in a CoMP communication system. delete 8. The method of claim 7, The column vectors of the second precoding matrix Corresponding to the first precoding matrices, A terminal device in a CoMP communication system. 8. The method of claim 7, Wherein the processor generates column indexes corresponding to each of the base stations in the second precoding matrix, Wherein the transmitting module transmits the column indexes along with the index of the second precoding matrix to the serving base station. A terminal device in a CoMP communication system. 10. The method of claim 9, The processor generates a Rank Indicator (RI) corresponding to the second precoding matrix, Wherein the transmitting module transmits the rank indicator to the serving base station together with an index corresponding to the second precoding matrix. A terminal device in a CoMP communication system. 12. The method of claim 11, The index corresponding to the upper rank precoding matrix and the rank indicator are And is included in one indicator and transmitted, A terminal device in a CoMP communication system.

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