WO2009088248A2

WO2009088248A2 - Multi-input and multi-output communication system for feedforward of interference vector indicator

Info

Publication number: WO2009088248A2
Application number: PCT/KR2009/000121
Authority: WO
Inventors: Yongxing Zhou; Joon-Il Choi
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2008-01-11
Filing date: 2009-01-09
Publication date: 2009-07-16
Also published as: WO2009088248A3

Abstract

Provided are a base station that supplies an interference vector indicator to a terminal and a terminal that recognizes at least one rest precoding vector through an interference vector indicator. The base station and the terminal configure a mapping table for an interference vector indicator, which indicates at least one rest precoding vector, between at least one bit and plural vectors based on the probability that the plural vectors included in a codebook is contained in a precoding matrix. At this time, the base station creates an interference vector indicator and the terminal recognizes at least one rest precoding vector by using the mapping table. In addition, the mapping table is configured differently according to plural modes.

Description

Multiple Input / Output Communication Systems Feedforwarding Interference Vector Indicators

Embodiments of the present invention relate to a multiple input / output communication system including a base station that feeds forward an interference vector indicator and a terminal that recognizes a precoding vector corresponding to another terminal based on the interference vector indicator.

Recently, researches are being actively conducted to provide various services such as multimedia services in a wireless communication environment and to transmit data at high quality and high speed. As part of this research, technologies related to multiple input multiple output (MIMO) communication systems using multiple channels in the spatial domain are rapidly developing.

In a MIMO communication system, a base station may use a spatial division multiplexing (SDM) scheme and a spatial division multiplexing access (SDMA) scheme. That is, the base station may transmit a plurality of data streams simultaneously through a plurality of antennas according to the SDM scheme, and may transmit a plurality of data streams to multiple users through the plurality of antennas according to the SDMA scheme.

In this case, in order for the base station to efficiently transmit the plurality of data streams using the plurality of antennas, it is necessary to identify channel information about downlink channels formed between the plurality of antennas and the users of the base station. Thus, users feed back channel information for downlink channels to the base station, and the base station constructs a precoding matrix for the users based on the channel information. At this time, the base station beamforms the data streams using a plurality of precoding vectors included in the precoding matrix.

However, the plurality of precoding vectors may act as interference with each other. At this time, the base station may feedforward the indicator for the precoding vector for the specific user and the indicator for the remaining precoding vector to the specific user. For example, if the active users are user A and user B, whose rank is 2, it is assumed that the precoding vector for user A is X and the precoding vector for user B is Y. At this time, the base station can inform the user A that the precoding vector is X, the interference vector is Y, and can inform the user B that the precoding vector is Y and the interference vector is X.

Since this feedforward process can increase the overhead of the communication system, it is necessary to study techniques for efficiently performing the feedforward process.

In a communication method of a base station according to an embodiment of the present invention, generating a precoding vector indicator indicating a target precoding vector for a target user among precoding vectors included in a precoding matrix, and a plurality of vectors included in a codebook. Constructing a mapping table between the plurality of vectors and at least one bit for an interference vector indicator indicating at least one remaining precoding vector in view of the probability that they are included in the precoding matrix and using the mapping table Generating the interference vector indicator.

In this case, the base station may adaptively change the mode configuring the mapping table, and the number of bits for the interference vector indicator as well as the mapping table may vary dynamically according to the mode configuring the mapping table.

The configuring of the mapping table may be a step of configuring the mapping table by classifying the plurality of vectors based on a probability that the plurality of vectors are included in the precoding matrix, wherein the probability is the plurality of vectors. Can be predicted based on the similarity between the field and the target precoding vector or the interference of the plurality of vectors with respect to the target precoding vector.

The configuring of the mapping table may include configuring the mapping table such that orthogonal vectors of the plurality of vectors are orthogonal to the target precoding vector, or are larger than a threshold value among the plurality of vectors. The mapping table may be configured to separately classify vectors having a high probability of being included in the precoding matrix and vectors having a lower probability of being included in the precoding matrix among the plurality of vectors.

In addition, the communication method of the terminal for the target user according to an embodiment of the present invention is based on the precoding vector indicator received from the base station among the precoding vectors included in the precoding matrix for the target user for the target user Recognizing, at least one bit for an interference vector indicator representing at least one remaining precoding vector in consideration of the probability that the plurality of vectors included in the codebook are included in the precoding matrix, and a mapping between the plurality of vectors Constructing a table and analyzing the interference vector indicator received from the base station based on the mapping table to recognize the at least one remaining precoding vector.

In addition, the base station according to an embodiment of the present invention, when the precoding vectors included in the precoding matrix are classified into a target precoding vector and at least one remaining precoding vector for the target user, a plurality of vectors included in the codebook A mapping table configuration module for configuring a mapping table between the plurality of vectors and at least one bit for an interference vector indicator indicating the at least one remaining precoding vector in view of the probability that they are included in the precoding matrix, the An indicator generation module for generating a precoding vector indicator indicating a target precoding vector, and generating the interference vector indicator using the mapping table, and providing an indicator for providing the precoding vector indicator and the interference vector indicator to the target user. Contains modules

In addition, the terminal according to an embodiment of the present invention, when the precoding vectors included in the precoding matrix are classified into a target precoding vector and at least one remaining precoding vector for the target user, the precoding vector indicator from the base station and An indicator receiving module for receiving an interference vector indicator, at least one bit for an interference vector indicator indicating the at least one remaining precoding vector in consideration of the probability that a plurality of vectors included in a codebook are included in the precoding matrix and the Recognizing the target precoding vector based on a mapping table configuration module and a precoding vector indicator constituting a mapping table between a plurality of vectors, and analyzing the interference vector indicator using the mapping table to determine the at least one Beck knows the rest of the precoding vector Whether a module.

A base station and a terminal according to an embodiment of the present invention construct a mapping table by estimating the probability that a plurality of vectors included in a codebook are included in a precoding matrix, thereby reducing the number of bits for the interference vector indicator and using the interference vector well. I can express it.

In addition, the terminal for the base station and the target user according to an embodiment of the present invention more accurately by using the similarity between the plurality of vectors and the target precoding vector or interference of the plurality of vectors with respect to the target precoding vector as a reference. A probability that a plurality of vectors included in a codebook are included in a precoding matrix can be predicted.

In addition, the base station and the terminal according to an embodiment of the present invention can transmit / receive an interference vector indicator having an optimized form by adaptively determining the mode configuring the mapping table.

1 is a diagram illustrating an example of a multi-user multi-input / output communication system.

2 is a diagram for explaining a precoding vector indicator and an interference vector indicator.

3 is a flowchart illustrating a process of determining a mode constituting a mapping table according to an embodiment of the present invention.

4 is a flowchart illustrating a process of determining a mode of configuring a mapping table according to another embodiment of the present invention.

5 is a flowchart illustrating an operation method of a base station and a terminal in a multiple input / output communication system according to an embodiment of the present invention.

6 is a block diagram illustrating a base station and a terminal in a multi-user multi-input / output communication system according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a multi-user MIMO communication system includes one base station 110 and a plurality of

terminals

120, 130, and 140. M transmit antennas are installed in the base station 110, and one or more receive antennas may be installed in each of the plurality of

terminals

120, 130, and 140.

Further, channels (downlink channels or uplink channels) are formed between the base station 110 and each of the plurality of

terminals

120, 130, and 140, and the base station 110 and each of the plurality of

terminals

120, 130, and 140 transmit / receive signals through the formed channel.

The base station 110 may transmit one or more data streams to the plurality of

terminals

120, 130, and 140. At this time, the base station 110 may generate a transmission signal by beamforming a plurality of data streams according to a spatial division multiplexing (Spatial Division Multiplexing Access) technique.

In this case, the base station 110 should grasp channel information on the downlink channels in order to perform beamforming or to select at least one of the plurality of

terminals

120, 130, and 140. In particular, the base station 110 selects at least one of the

terminals

120, 130, and 140 using various user selection algorithms such as Greedy User Selection, Semi-orthogonal User Selection (SUS), etc. based on the channel information. You can choose.

The base station 110 may transmit pilot signals to the plurality of

terminals

120, 130, and 140 through a downlink channel. Here, the pilot signal is a signal well-known to the base station 110 and the plurality of

terminals

120, 130, and 140. In this case, each of the plurality of

terminals

120, 130, and 140 may estimate downlink channels formed between the base station 110 and the plurality of

terminals

120, 130, and 140 using a pilot signal. In addition, each of the plurality of

terminals

120, 130, and 140 provides feedback information on the estimated downlink channels to the base station 110.

The base station 110 selects at least one of the plurality of

terminals

120, 130, and 140 using the feedback information. Here, it is assumed that all of the

terminals

120, 130, and 140 are selected as active terminals.

At this time, the base station 110 determines a precoding matrix for precoding or beamforming a plurality of data streams for the plurality of

terminals

120, 130, and 140 based on the feedback information. In particular, the base station 110 may determine a precoding matrix by selecting some of the plurality of vectors included in the codebook as precoding vectors based on the feedback information.

In order to increase the throughput of the multi-user multi-input / output communication system illustrated in FIG. 1, each of the plurality of

terminals

120, 130, and 140 should be able to grasp the corresponding precoding vector and the remaining precoding vectors. For example, assume that the precoding matrix includes precoding vectors v _1, v _2, v ₃ . Here, each of v _1, v _{2, and} v ₃ is a precoding vector for each of the plurality of

terminals

120, 130, and 140.

UE 1 120 should be able to determine that the precoding vector for itself is v ₁ , and that v _{2 and} v ₃ are interference vectors for the precoding vector v ₁ for itself as the remaining precoding vectors. Similarly, UE 2 130 should be able to determine that the precoding vector for itself is v ₂ , and that v _{1 and} v ₃ are interference vectors for precoding vector v ₂ for itself as the remaining precoding vectors. K 140 must be able to determine that the precoding vector for itself is v ₃ and that v _{1 and} v ₂ are the interference vectors for the precoding vector v ₃ for itself as the remaining precoding vectors.

The base station 110 transmits feedforward information including a precoding vector and indicators capable of identifying the remaining precoding vectors to the plurality of

terminals

120, 130, and 140. In this case, each of the plurality of

terminals

120, 130, and 140 may grasp the corresponding precoding vector and the remaining precoding vectors using the feedforward information.

In addition, the base station 110 beamforms the data streams with the precoding vectors included in the precoding matrix to generate a transmission signal. In this case, since each of the plurality of

terminals

120, 130, and 140 knows the corresponding precoding vector and the remaining precoding vectors in advance, the interference existing in the received signal may be removed.

Before describing FIG. 2, it is assumed that a base station provided with M transmit antennas and a plurality of users (terminals) use the same codebook C. FIG. Here, the codebook C includes L unitary matrices, and the size of each of the unitary matrices is M × M. In this case, Codebook C

The size of the codebook, which is the number of column vectors included in the codebook, is Nq = LM. In this case, codebook C

It can also be expressed as.

Referring to FIG. 2, k, i, j, and m are indices of users, and u _k , u _i , u _j , and u _m are precoding vectors for users k, i, j and m, respectively. Where u _i , u _j , u _m are interference vectors as the remaining precoding vectors for precoding vector u _k for user k.

Log ₂ (Nq) bits are required to represent any one of the Nq vectors. When the number of users served simultaneously is P _SDMA , the base station uses P _SDMA X log ₂ (Nq) to express the precoding vector u _k and the remaining precoding vectors u _i , u _j , u _m for user k. You can see that bits are required.

The transmission of the indicators for the precoding vector and the remaining precoding vectors to a plurality of users will be referred to as precoding matrix indicator (PMI) signaling. PMI signaling is performed on a physical downlink control channel (PDCCH) and may cause a lot of overhead in a communication system. Since this overhead reduces the performance of the communication system, there is a need for a technique for efficient PMI signaling with little overhead.

Before describing FIG. 3, it is assumed that the base station is provided with M transmit antennas and K active users. Here, N _r receive antennas are installed in each of the active users, and the base station and the active users have codebook C

Suppose we use Here, each of v ₁ , v ₂ , and v _Nq is a column vector of size MX 1, and the rank r is the number of users (P _SDMA ) served simultaneously. It is also assumed that there is a constraint that the size of PMI signaling for rank r must be smaller than B _r .

1. Various Modes of Mapping Table

(1) a mode constituting a mapping table for classifying a plurality of vectors included in a codebook into orthogonal and non-orthogonal vectors for a target precoding vector u _k (minimum signaling mode)

TABLE 1

A base station according to an embodiment of the present invention may configure a mapping table as shown in Table 1 above. Here, the user k may also configure the same mapping table through the same method as the base station.

Base station according to an embodiment of the present invention

By using the bits, a precoding vector indicator indicating the target precoding vector u _k may be generated. For example, when Nq is 8, the precoding vector indicator indicates the target precoding vector using 3 bits.

In addition, the base station may separate Nq vectors included in the codebook into orthogonal vectors and non-orthogonal vectors for the target precoding vector u _k in order to generate an interference vector indicator indicating the remaining precoding vectors other than the target precoding vector. Can be. In addition, the base station individually represents each orthogonal vector for the target precoding vector u _k , and may represent non-orthogonal vectors in one case (half bit).

For example, v ₁ , v ₂ , v ₃ , v ₄ ,. . It is assumed that the orthogonal vectors for the target precoding vector v ₁ of., v _{Nq = 8} are v ₂ , v ₃ and v ₄ , and the remaining vectors are non-orthogonal vectors. In this case, the interference vector indicator may be represented by 2 bits. That is, the base station maps v ₂ to '00', v ₃ to '01' and v ₄ to '10'. The base station also maps all of the remaining vectors to '11'. When the base station is at least one of v ₂ , v ₃ , and v ₄ except for the target precoding vector v ₁ from the precoding vectors included in the precoding matrix, '00', At least one of '01' and '10' is determined as the interference vector indicator. However, when none of the remaining precoding vectors is any one of v ₂ , v ₃ , and v ₄ , the base station determines '11' as the interference vector indicator. As a result, it can be seen that the base station can generate the interference vector indicator using 2 bits.

When the precoding matrix includes the target precoding vector, the probabilities that the plurality of vectors included in the codebook are included in the precoding matrix may vary. However, in a general case, it can be predicted that orthogonal vectors for the target precoding vector have a relatively high probability of being included in the precoding matrix, and that the non-orthogonal vectors have a relatively low probability of being included in the precoding matrix. Using this fact, the base station according to the embodiment of the present invention can identify the orthogonal vectors individually, and can configure a mapping table that treats the non-orthogonal vectors as one case.

Referring to FIG. 3, the base station according to an embodiment of the present invention calculates t ₀ according to the minimum signaling mode (S310). Where t ₀ =

+

In the mapping table according to the minimum signaling mode, the bits for the interference vector indicator and the plurality of vectors included in the codebook are mapped to each other so as to individually identify the orthogonal vectors, and the non-orthogonal vectors are regarded as one case. .

In this case, as will be described below, the base station according to an embodiment of the present invention may configure a mapping table to individually identify some of the non-orthogonal vectors.

In addition, the base station according to an embodiment of the present invention compares t ₀ and B _r (S320).

If t ₀ is greater than or equal to B _r , the base station determines the mapping table configured according to the minimum signaling mode, and terminates the process of determining the mode configuring the mapping table. Then, the interference vector indicator is generated according to the determined mapping table and provided to the user.

(2) a mode constituting a mapping table that additionally selects at least one non-orthogonal vector for the target precoding vector u _k

Conversely, if t ₀ is less than B _r , the base station according to an embodiment of the present invention changes the mapping table so that one non-orthogonal vector can be identified separately, and the size of PMI signaling corresponding to the changed mapping table. Calculate t ₁ (S330).

The changed mapping table may inform the user of the remaining precoding vectors more accurately than the mapping table according to the minimum signaling mode, but may have a larger size t ₁ of PMI signaling. The calculation process of t ₁ is described in detail below.

In addition, one additional non-orthogonal vector may be determined based on the similarity between the plurality of vectors and the target precoding vector or the interference of the plurality of vectors with respect to the target precoding vector. Here, the similarity between the plurality of vectors and the target precoding vector or the interference of the plurality of vectors with respect to the target precoding vector is a concept corresponding to the probability that the plurality of vectors are included in the precoding matrix.

Signal to Interference Ratio (SIR) _{i and j} of the i th beam vector with respect to the j th beam vector may be expressed by Equation 1 below.

[Equation 1]

here,

Is the spatial angle interval at which the beamforming gain of the i th beam is maximized,

silver

Is a spatial angle that belongs to

Silver space angle

It represents the beamforming gain of the i-th beam of the furnace. U _i is the i th beam vector,

Is the wavelength, d is the spacing between the transmit antennas, and n is the index of the transmit antenna.

In addition, the base station according to an embodiment of the present invention compares the calculated size t ₁ of the PMI signaling with a predetermined limit B _r (S340).

If t ₁ is greater than the predetermined limit B _r , the base station checks whether t ₁ and B _r are the same (S350). If t ₁ and B _r are equal, the base station terminates all processes and finally confirms the mapping table generated in step S330. If t ₁ and B _r are not equal, step S310 is repeated.

On the contrary, if t ₁ is smaller than the predetermined limit B _r , the base station changes the mapping table so as to separately identify another non-orthogonal vector separately. As these processes are repeated repeatedly, the base station according to an embodiment of the present invention changes the mapping table so as to separately identify the r-1 th non-orthogonal vector and calculates t _r-1 ( S360).

Then, the base station checks whether the calculated t _r-1 and B _r are the same (S370). If t _r-1 and B _r are equal, the mapping table generated in step S360 is finally determined, and if t _r-1 and B _r are not equal, the previous step is repeated. Here, the previous step is to change the mapping table so as to separately identify the r-2 th non-orthogonal vector, and calculate t _r-2 .

The q non-orthogonal vectors for the target precoding vector u _k added to be individually identified in the mapping table may be selected through the following process. Where q is 1, 2,. . , r-1.

Orthogonal Basis Setup: Find all possible sets. In this case, each of the sets is composed of rq vectors, and the rq vectors (target precoding vector u _k and

rq-1 vectors) orthogonal to each other. Here, these sets

Let's call it.

-

Find a possible set of q non-orthogonal vectors that are added to be individually identified in the mapping table for the target precoding vector u _k based on. Where a possible set of q non-orthogonal vectors

Where G represents the number of combinations of q non-orthogonal vectors taken from codebook C, and y is

A specific q non-orthogonal vectors selected based on Then, all y is found by using Equation 2 below.

[Equation 2]

The size of the PMI signaling

Calculate bits Here, P _q-1 represents all possible cases in the mapping table generated in the previous step, and P _{added, q} represents cases _added to the mapping table in the current step. Also, +1 represents all vectors not selected.

As a result, when q-1 non-orthogonal vectors are added to be individually identified, the mapping table may be represented as shown in Table 2 below.

TABLE 2

The base station and the user of the present invention may transmit / receive an interference vector indicator indicating the remaining precoding vectors included in the precoding matrix by using the mapping tables shown in Tables 1 and 2 described above. In this case, the base station and the user may determine a mode configuring the mapping table appropriately in consideration of the number of bits for the interference vector indicator, and generate and use a mapping table corresponding to the determined mode.

(3) a mode constituting a mapping table for additionally selecting interference vectors based on a probability that a plurality of vectors are included in a precoding matrix through an SIR or the like

Before describing FIG. 4, the base station according to another embodiment of the present invention may not distinguish between orthogonal and non-orthogonal vectors for the target precoding vector in order to select vectors added to the mapping table. That is, adding orthogonal vectors for the target precoding vector to the mapping table preferentially means that the orthogonal vectors are determined to be determined as precoding vectors together with the target precoding vector. At this time, the base station according to another embodiment of the present invention does not discriminate orthogonal vectors and non-orthogonal vectors, and adds to the mapping table by predicting a probability that the plurality of vectors are included with the target precoding vector in the precoding matrix. You can choose which vectors to use. In particular, the probability that the plurality of vectors are included with the target precoding vector in the precoding matrix can be predicted based on the similarity or SIR between the target precoding vector and the plurality of vectors.

In this case, the interference vectors for the target precoding vector u _k added to the mapping table may be selected as vectors corresponding to an SIR larger than a predetermined threshold. And, the number of interference vectors can be adjusted by appropriately changing the threshold.

In the case of a 3-bit DFT codebook, the matrix TT may be represented by Equation 3 below.

[Equation 3]

Here, the elements of the i th row and the j th column of the matrix TT are

to be.

At this time, an embodiment of the present invention may select interference vectors that can be individually identified in a mapping table among a plurality of vectors included in a codebook using optimization criteria described in Equation 4 below.

[Equation 4]

For example, assume that the rank is 2, the threshold _q is 5 ² = 25, and u _k is the target precoding vector. For u _k = v ₁ , since elements in rows 3 and ₁ of the TT matrix are greater than 5, {v ₃ } is chosen as the interference vector that can be individually identified in the mapping table. Similarly, the {} v4 is selected with respect to u _k = v _2, v is _{1} is selected for u _k = v _3. With respect to _{_{_{u k = v 4 {v 2}}} } is selected, and the v _{7} is selected for u _k = v _5. And, u _k = v for _{_{_{6 {v 8}, u k}}} = v v for ₇ _{5}, a {v _6} is selected for u _k = v _8.

In addition, an embodiment of the present invention may adjust the threshold _q . For example, threshold _q is 3.6 ² = if 12.96 _{_{is, u k = v 1 {v}} 3}, {v 6}, {v 7} a, u _k = v for the _second with respect to {v _4}, { v ₇ }, {v ₈ } are selected as interference vectors. And for u _k = v ₃ , {v ₁ }, {v ₅ }, {v ₈ }, for u _k = v ₄ , {v ₂ }, {v ₅ }, {v ₆ }, u _k = v For v ₅ {v ₄ }, {v ₄ }, {v ₇ }, u _k = v ₆ {v ₁ }, {v ₄ }, {v ₈ } are selected as interference vectors. And for u _k = v ₇ , {v ₁ }, {v ₂ }, {v ₅ }, and for u _k = v ₈ , {v ₂ }, {v ₃ }, {v ₆ } are interference vectors. Is selected.

2. Specific examples of mapping tables

(1) Example of a mode (minimum signaling mode) constituting a mapping table for classifying a plurality of vectors included in a codebook into orthogonal and non-orthogonal vectors for a target precoding vector u _k

Assume a 3 bit DFT codebook, 4 transmit antennas, rank is 2. In this case, the mapping table corresponding to the minimum signaling mode may be shown in Table 3 below. For reference, { v ₁ } { v ₂ } { v ₃ } { v ₄ } are united in the DFT codebook.

TABLE 3

Referring to Table 3 above, the interference vector indicator includes two bits. The interference vector indicator maps them to '00', '01', and '10' to individually identify the interference vectors 1, 2, and 3 of the plurality of vectors. The remaining vectors except for interference vectors 1, 2, and 3 are all mapped to '11'.

For example, interference vectors 1, 2, and 3 orthogonal to v ₁ are { v ₂ } { v ₃ } { v ₄ }, and the non-orthogonal vectors for v ₁ are { v ₅ } { v ₆ } { v ₇ } { v ₈ }. In this case, when the precoding matrix includes any one of { v ₂ } { v ₃ } { v ₄ }, the base station determines one of '00', '01', and '10' as the interference vector indicator. . However, when any one of { v ₅ } { v ₆ } { v ₇ } { v ₈ } is included in the precoding matrix, the base station determines '11' as the interference vector indicator.

In addition, the embodiment of the present invention may be applied to a codebook for the case where the number of transmit antennas of 3GPP LTE2 shown in Table 4 is two.

TABLE 4

In this case, when the rank is 2 in the codebook of 3GPP LTE2, the mapping table may be configured as shown in Equation 5 below.

TABLE 5

Here, 'Unitary Pairing' denotes a vector v ₂ orthogonal to v ₁ , and 'Non-Unitary Pairing' denotes { v ₃ } { v ₄ } { v ₅ } { v ₆ }.

(2) Specific example of mapping table for additionally selecting interference vectors based on SIR

Assume that it is a 3 bit DFT codebook, the number of transmit antennas is 4 and the rank is 2. In addition, it is assumed that the threshold _q of Equation 4 is 3.6 ² = 12.96. In this case, the mapping table may be represented as shown in Table 6 below.

TABLE 6

Referring to Table 6, when threshold _q is 3.6 ² = 12.96, three interference vectors are determined for each target precoding vector. For example, for u _k = v ₁ {v ₃ }, {v ₆ }, {v ₇ } are selected as interference vectors. At this time, each of {v ₃ }, {v ₆ }, and {v ₇ } is mapped to '00', '01', and '10'.

Similarly, u _k = with respect to _{_{v 2 {v 4}, {}} v 7}, {v 8}, u k = v 3 to about _{_{{v 1}, {v 5}} }, {v 8}, u k = v for _{_{4 {v 2}, {v}} 5}, {v 6}, u k = v for _{_{5 {v 4}, {v}} 4}, {v 7}, u k = v for ₆ {v ₁ }, {v ₄ }, and {v ₈ } are selected as interference vectors. And for u _k = v ₇ , {v ₁ }, {v ₂ }, {v ₅ }, and for u _k = v ₈ , {v ₂ }, {v ₃ }, {v ₆ } are interference vectors. Is selected.

4, the base station according to an embodiment of the present invention calculates t ₀ according to the minimum signaling mode (S410).

Here, the minimum signaling mode in FIG. 4 refers to adding one case to the mapping table. That is, the minimum signal run mode determines only the best vector of one of the plurality of vectors as an interference vector, allows only the determined interference vector to be individually identified, and considers the remaining vectors as one case. For example, according to the minimum signaling mode, only {v ₃ } is selected as the interference vector for the target precoding vector u _k = v ₁ .

In addition, the base station according to an embodiment of the present invention compares t ₀ and B _r (S420). If t ₀ is greater than or equal to B _r , the base station finally determines the mapping table according to the minimum signaling mode, and terminates all processes. However, if t ₀ is smaller than B _r , the base station adjusts the threshold of Equation 4 so that three vectors are added as interference vectors of the mapping table, and calculates t ₁ (S430).

In addition, the base station according to an embodiment of the present invention compares t ₁ and B _r (S440). If t ₁ is not less than B _r , the base station checks whether t ₁ and B _r are the same (S450). If t ₁ and B _r are the same, the mapping table generated in step S430 is finally determined, and all processes are terminated. On the contrary, if t ₁ and B _r are not the same, step S410 is performed again.

In addition, the base station according to an embodiment of the present invention is a process of adjusting the threshold value so that three vectors are added sequentially and the process of comparing the size of the PMI signaling corresponding to the changed mapping table with B _r by adjusting the threshold value. Repeat. These, processes are shown in steps S460 and S470.

In step S470, if t _h-1 (where h is an integer greater than 0) is equal to B _r , a mapping table including 2 ^h-1 interference vectors is finally determined. In contrast, if t _h-1 is not equal to B _r , the process of generating a mapping table including 2 ^h-2 interference vectors is performed again, and all processes are terminated.

Referring to FIG. 5, the base station according to an embodiment of the present invention generates a precoding vector indicator indicating a target precoding vector for a target user among precoding vectors included in the precoding matrix (S510).

Further, according to an embodiment of the present invention, the base station includes at least one bit for an interference vector indicator indicating at least one remaining precoding vector in consideration of a probability that a plurality of vectors included in a codebook are included in the precoding matrix; A mapping table between the plurality of vectors is configured (S520).

In this case, the base station may configure the mapping table by classifying the plurality of vectors based on the probability that the plurality of vectors are included in the precoding matrix. For example, only a predetermined number of vectors may be determined as interference vectors of the mapping table according to a high probability that the plurality of vectors are included in the precoding matrix. In this case, vectors not selected as interference vectors are considered one case.

Further, as described above, the base station determines the plurality of vectors in the precoding matrix based on the similarity between the plurality of vectors and the target precoding vector or the interference of the plurality of vectors with respect to the target precoding vector. The probability to be included can be predicted. The base station may determine only the vectors having a probability included in the precoding matrix higher than the predetermined threshold value as the interference vectors of the mapping table. At this time, vectors having a probability included in the precoding matrix lower than the predetermined threshold value are regarded as one case.

The base station may configure a mapping table that distinguishes the plurality of vectors into orthogonal and non-orthogonal vectors for the target precoding vector, and considers only orthogonal vectors as interference vectors.

In addition, the base station according to an embodiment of the present invention generates an interference vector indicator indicating the remaining precoding vector other than the target precoding vector among the precoding vectors included in the precoding matrix by using any one of various mapping tables. (S530).

At this time, the mapping table used by the base station is also used by the terminal.

In addition, the base station according to an embodiment of the present invention provides the generated precoding vector indicator and the interference vector indicator to the terminal (S540).

In addition, the terminal for the target user according to an embodiment of the present invention recognizes the target precoding vector for the target user of the precoding vectors included in the precoding matrix based on the precoding vector indicator received from the base station ( S550).

In addition, the terminal for the target user according to an embodiment of the present invention configures the mapping table in the same manner as the base station (S560).

In addition, the terminal for the target user according to an embodiment of the present invention recognizes the remaining precoding vectors included in the precoding matrix by analyzing the interference vector indicator using the configured mapping table (S570).

In addition, the terminal for the target user according to an embodiment of the present invention removes the interference from the received data signal using the recognized precoding vector and the remaining precoding vectors (S580).

The methods according to the invention can be implemented in the form of program instructions that can be executed by various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. Program instructions recorded on the media may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well-known and available to those having skill in the computer software arts. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

Referring to FIG. 6, the multi-user multi-input / output communication system according to an embodiment of the present invention includes a base station 610 and

K terminals

620, 630, and 640.

The base station 610 includes a mapping table configuration module 611, an indicator generation module 612, and an indicator providing module 613.

The mapping table construction module 611 may include at least one bit for the interference vector indicator indicating at least one remaining precoding vector in consideration of the probability that the plurality of vectors included in the codebook are included in a precoding matrix, and the plurality of vectors. Configure the mapping table between them. Since the mapping table configuration module 611 may apply the principle of configuring the mapping table described with reference to FIGS. 1 to 5 as it is, detailed description thereof will be omitted.

In addition, the indicator generation module 612 generates a precoding vector indicator indicating the target precoding vector, and generates the interference vector indicator using the mapping table. In addition, the indicator providing module 613 provides the precoding vector indicator and the interference vector indicator to the target user.

In addition, the terminal K 640 includes a mapping table configuration module 641, an indicator receiving module 642, and a vector recognition module 643.

The mapping table configuration module 641 of the terminal K 640 also configures the mapping table using the same principle as the mapping table configuration module 642 of the base station 610.

In addition, the indicator receiving module 642 receives the precoding vector indicator and the interference vector indicator from the base station 610, and the vector recognition module 643 uses the configured mapping table, the precoding vector indicator, and the interference vector indicator to target-free. Recognize a coding vector and at least one remaining precoding vector.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

Claims

Generating a precoding vector indicator indicating a target precoding vector for the target user among the precoding vectors included in the precoding matrix;

A mapping table between the plurality of vectors and at least one bit for an interference vector indicator indicating at least one remaining precoding vector in consideration of the probability that the plurality of vectors included in the codebook are included in the precoding matrix. step; And

Generating the interference vector indicator using the mapping table

Communication method of a base station in a multiple input and output communication system comprising a.
The method of claim 1,

Configuring the mapping table

And configuring the mapping table by classifying the plurality of vectors based on a probability that the plurality of vectors is included in the precoding matrix.
The method of claim 1,

Configuring the mapping table

Predict the probability that the plurality of vectors are included in the precoding matrix based on the similarity between the plurality of vectors and the target precoding vector or the interference of the plurality of vectors with respect to the target precoding vector, and the mapping Comprising a step of constructing a table communication method of the base station in a multiple input and output communication system.
The method of claim 1,

Configuring the mapping table

And configuring the mapping table such that orthogonal vectors of the target precoding vectors are separately classified among the plurality of vectors.
The method of claim 1,

Configuring the mapping table

The mapping table may be configured such that vectors having a probability of being included in the precoding matrix higher than a threshold among the plurality of vectors and vectors having a probability of being included in the precoding matrix lower than a threshold among the plurality of vectors are classified separately. A communication method of a base station in a multiple input and output communication system, characterized in that the step of configuring.
The method of claim 1,

Determining a mode for configuring the mapping table for the number of bits for the interference vector indicator

More,

Configuring the mapping table

And configuring the mapping table according to a mode for configuring the mapping table.
The method of claim 6,

And the number of bits for the interference vector indicator is controlled under a predetermined constraint.
The method of claim 1,

Providing the precoding vector indicator and the interference vector indicator to the target user

Communication method of a base station in a multiple input and output communication system, characterized in that it further comprises.
The method of claim 1,

And the target user configures the same mapping table.
Recognizing a target precoding vector for the target user among the precoding vectors included in the precoding matrix based on the precoding vector indicator received from the base station;

A mapping table between the plurality of vectors and at least one bit for an interference vector indicator indicating at least one remaining precoding vector in consideration of the probability that the plurality of vectors included in the codebook are included in the precoding matrix. step; And

Analyzing the interference vector indicator received from the base station based on the mapping table to recognize the at least one remaining precoding vector.

The communication method of the terminal for the target user in a multiple input and output communication system comprising a.
The method of claim 10,

Removing interference present in the received data signal using the target precoding vector and the at least one remaining precoding vector.

The communication method of the terminal for the target user in a multiple input and output communication system, characterized in that it further comprises.
The method of claim 10,

Configuring the mapping table

And configuring the mapping table by classifying the plurality of vectors based on the probability that the plurality of vectors are included in the precoding matrix.
The method of claim 10,

Configuring the mapping table

Predict the probability that the plurality of vectors are included in the precoding matrix based on the similarity between the plurality of vectors and the target precoding vector or the interference of the plurality of vectors with respect to the target precoding vector, and the mapping Comprising a step of configuring a table communication method of a terminal for a target user in a multiple input and output communication system.
The method of claim 10,

The base station is configured to configure the same mapping table, the communication method of the terminal for the target user in a multiple input and output communication system.
A computer-readable recording medium having recorded thereon a program for performing the method of claim 1.
When the precoding vectors included in the precoding matrix are classified into a target precoding vector and at least one remaining precoding vector for the target user,

Construct a mapping table between the plurality of vectors and at least one bit for an interference vector indicator representing the at least one remaining precoding vector in consideration of the probability that the plurality of vectors included in the codebook are included in the precoding matrix. A mapping table configuration module;

An indicator generation module for generating a precoding vector indicator indicating the target precoding vector, and generating the interference vector indicator using the mapping table; And

Indicator providing module for providing the precoding vector indicator and the interference vector indicator to the target user

A base station for a multiple input and output communication system comprising a.
The method of claim 16,

The mapping table configuration module

Predict the probability that the plurality of vectors are included in the precoding matrix based on the similarity between the plurality of vectors and the target precoding vector or the interference of the plurality of vectors with respect to the target precoding vector, and the mapping A base station for a multiple input and output communication system, characterized in that the table is configured.
When the precoding vectors included in the precoding matrix are classified into a target precoding vector and at least one remaining precoding vector for the target user,

An indicator receiving module for receiving a precoding vector indicator and an interference vector indicator from a base station;

Construct a mapping table between the plurality of vectors and at least one bit for an interference vector indicator representing the at least one remaining precoding vector in consideration of the probability that the plurality of vectors included in the codebook are included in the precoding matrix. A mapping table configuration module; And

A vector recognition module that recognizes the target precoding vector based on the precoding vector indicator and analyzes the interference vector indicator using the mapping table to recognize the at least one remaining precoding vector.

Terminal for a target user in a multiple input and output communication system comprising a.
The method of claim 18,

A processor module for canceling interference present in the received data signal using the target precoding vector and the at least one remaining precoding vector

Terminal for the target user in a multiple input and output communication system, characterized in that it further comprises.