KR101402248B1 - Apparatus and method for eliminate interference in multi-user multiple input multiple output wireless communication system - Google Patents

Abstract

The present invention relates to an apparatus and method for simplifying a signal processing process for eliminating interference in a multi-user MIMO wireless communication system by pre-selecting user terminals for interference cancellation and receiving interference signal information from terminals And a user selecting unit for selecting a group of terminals to perform an interference cancellation process by calculating an interference plus noise correlation matrix (INCM) index of all terminals in the cell using the received interference information, The cell interference can be eliminated by using a smaller amount of computation than the conventional cell interference cancellation process.

A multi-user multiple input multiple output (MIMO), a precoding matrix, an interference plus noise correlation matrix (INCM) index.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a multi-user multi-input multi-output wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-user MIMO (Multi-User Multiple Input Multiple Output) wireless communication system, and more particularly, And simplifying the signal processing procedure for the signal processing apparatus.

2. Description of the Related Art [0002] Recently, as a demand for high-speed and high-quality data transmission has increased, a MIMO (Multiple Input Multiple Output) wireless communication system using a plurality of transmitting and receiving antennas has been attracting attention. The MIMO technique performs communication using a plurality of streams through a plurality of antennas, thereby greatly improving channel capacity as compared with the case of using a single antenna. For example, if both the transmitting and receiving ends use M transmit and receive antennas, the channel between each antenna is independent, and the bandwidth and total transmit power are fixed, the average channel capacity is increased by M times as compared to a single antenna . A multi-input / output system can be applied not only to a pair of transmitting and receiving ends but also between one transmitting end and a plurality of receiving ends. For example, a multi-user MIMO (Multi-User Multiple Input Multiple Output) wireless communication system is constructed assuming a base station having a plurality of transmit antennas and a plurality of terminals having at least one antenna.

The multi-user MIMO wireless communication system increases frequency efficiency by allowing a plurality of users to simultaneously use space resources secured by using a plurality of antennas. In the case of a downlink for transmitting information from a base station to a terminal, the base station pre-processes information to a plurality of users at the same time, and each of the plurality of users checks information from the signal received through each channel . In order to secure high channel capacity, an alternative is needed to eliminate multi-user interference, which is interference between terminals, and interference from neighboring cells.

As a method for eliminating the interference from the neighboring cell as described above, it is possible to use a method entitled " Device and method for interference cancellation in a multi-user MIMO wireless communication system (Samsung Electronics) ".

However, the above method has solved the limitation problem due to the limitation of the number of receiving antennas using the eigen-mode combining in the receiver of the multi-user multi-antenna system and obtained the close performance of the DPC coding, The channel capacity is compared with the transport stream mode combination of all the users in the cell to find the user combination having the best channel capacity, so that there is a disadvantage that the complexity increases when the size of the active user set increases .

It is an object of the present invention to provide an apparatus and a method for simplifying the operation of eliminating multi-user interference in a multi-user multi-antenna system.

It is another object of the present invention to provide an apparatus and method for selecting a user for eliminating cell interference using an interference and noise correlation matrix of a user terminal in a cell in a multiuser multi-antenna system.

It is still another object of the present invention to provide an apparatus and method for performing a cell interference process for users who want to remove a cell interference in a multi-user multi-antenna system.

According to a first aspect of the present invention, a base station for interference cancellation in a multi-user MIMO wireless communication system receives interference signal information from terminals, And a user selecting unit for selecting a group of terminals to perform an interference cancellation process by calculating an interference plus noise correlation matrix (INCM) index of all the terminals.

According to a second aspect of the present invention, there is provided a method of canceling interference in a multi-user MIMO wireless communication system, the method comprising: receiving interference signal information from terminals; Calculating interference and noise correlation matrix (INCM) indexes of all the terminals, and selecting a group of terminals to perform the interference cancellation process using the calculated interference and noise correlation matrix index The method comprising the steps of:

As described above, according to the present invention, cell interference can be eliminated through a smaller amount of computation than a conventional cell interference cancellation process by selecting user terminals for cell interference cancellation using the INCM index of all users in the cell through the INCM index.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Hereinafter, an apparatus and method for simplifying signal processing for cell interference cancellation by pre-selecting user terminals for interference cancellation in a multi-user MIMO wireless communication system according to the present invention will be described.

1 is a schematic diagram of a multi-user MIMO wireless communication system in accordance with the present invention.

Referring to FIG. 1, the BS 110 simultaneously transmits data signals to the MSs 120-1 through 120-K using a plurality of transmission antennas. At this time, a data signal transmitted by the base station 110 is received by each of the terminals 120-1 to 120-K via the corresponding channel Hk. In addition, an interference signal from a neighbor cell is received at each of the terminals 120-1 to 120-K. Therefore, each of the terminals 120-1 to 120-K eliminates interference from neighboring cells and interference due to signals to other terminals.

Herein, the base station 100 selects terminals of users that are primarily activated based on an interference plus noise correlation matrix (INCM), and processes the selected terminals to remove the interference of the selected terminals.

Here, the base station 100 may calculate the INCM of all users in the cell using the interference signal information received from the terminals, thereby selecting the terminals of the active users.

For the detailed description of the present invention, it is described that the terminal of the base station 100, which is the user selection unit 102, is selected as the terminal of the activated users. However, in the user selection unit 102 defined in the present invention, May be included in the description of the base station 100 in general.

2 is a block diagram illustrating a configuration of a user selection unit in a multi-user MIMO wireless communication system according to an exemplary embodiment of the present invention.

2, the user selector 200 may include an interference plus noise correlation matrix (INCM) calculating unit 202 and an INCM index comparing unit 204. The interference plus noise correlation matrix have.

The user selection unit 200 is a device of a base station for selecting terminals of active users who wish to perform interference cancellation. The user selection unit 200 selects an interference plus noise correlation matrix INCM Covariance matrix of the terminals.

The INCM index calculation unit 202 of the user selection unit 200 calculates an interference plus noise correlation matrix INCM (interference plus noise (INCM)) indicating interference of each user affecting the system using the interference signal information received from the terminals, Covariance matrix. Here, the INCM index calculation unit 202 calculates the INCM indexes of all user terminals in the cell.

The INCM index comparing unit 204 of the user selecting unit 200 sequentially compares the INCM indexes of all user terminals in the cell calculated by the INCM index calculating unit 202.

The user selector 200 selects the terminals of the active users who want to perform interference cancellation using the INCM index size compared by the INCM index comparator 204. [ For example, the BS may select user terminals having a small INCM index value as terminals of active users who wish to perform interference cancellation.

The base station including the user selection unit 200 selects a primary active user set based on the INCM and removes the cell interference of the selected users so that the base station 200 having a relatively small amount of computation and complexity, And a role of the terminal can be performed by the base station.

As described above, the present invention has been described in terms of an apparatus for pre-selecting user terminals for interference cancellation in a multi-user MIMO wireless communication system to simplify a signal processing process for cell interference cancellation. A method for simplifying signal processing for cell interference cancellation by pre-selecting user terminals for interference cancellation in a multi-user MIMO wireless communication system using the apparatus according to an exemplary embodiment will be described.

3 is a flowchart illustrating an operation of a base station in a multi-user MIMO wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, in step 301, the BS 100 determines whether interference signal information is received from the MSs. Herein, the BS 100 may receive channel information necessary for interference cancellation from the MSs together with the interference information. In addition, the interference information may be referred to as an interference plus noise correlation matrix (INCM) indicating the interference of each user affecting the system.

Then, the BS 100 proceeds to step 303 and calculates the INCM of all users in the cell using the interference signal information received from the MSs. Herein, the base station 100 processes the INCM index calculation unit 202 to calculate an INCM index, which is an index indicating interference of a user, using the received information.

In step 305, the BS 100 compares the INCM index measured in step 303, and then proceeds to step 307 to select a group of users to remove the interference.

Here, the INCM exponent calculation unit 202, which has received the instruction from the base station 100, may calculate the INCM exponent according to the following situation. In other words, when the BS 100 assumes that the channel states of the users are on the average, and the distribution of the users is not uniformly distributed from the BS to a similar distance, the INCM index Can be calculated.

First, when it is determined that the channel conditions of each user are on average, the BS 100 may calculate the INCM index using Equation (1) below.

Here, R _Zk represents the INCM index of the k-th user.

Also, when the base station 100 determines that the distribution of users is not uniformly distributed at a similar distance from the base station, the base station 100 may calculate the INCM index using Equation (2) below.

Here, R _Zk denotes an INCM exponent of a k-th user, and H _k denotes a channel matrix of a k-th user.

Here, the base station 100 can calculate R _Zk , which represents the INCM index of the k-th user in Equation (1) to Equation (2) using Equation (3).

Wherein R _Zk is a k-th user of the interference and noise covariance matrix, the H _{I, K} is the k-th user of the interference channel, the _{I x, K} is the k-th user of the interference signal, wherein σ means the noise power.

In addition, when the BS 100 determines that the channel status of each user is on the average, it selects a user corresponding to a smaller value of the INCM index when selecting a group of users to remove the interference . This means that users who are relatively distant from the base station 100 are selected. Meanwhile, when it is confirmed that the distribution of users is not uniformly distributed at a similar distance from the base station 100, the BS 100 selects a group of users who want to remove the interference, . This means to select a group of users considering the path loss of the channel according to the distance from the base station 100.

Thereafter, the BS 100 proceeds to step 309 to perform an interference cancellation process.

Herein, the interference cancellation process of the base station 100 may be performed, for example. The base station 100 may transmit weight matrix information and precoding matrix information, which are information required for the interference cancellation process of the terminal, Lt; / RTI > However, the present invention relates to an algorithm for selecting user terminals to perform interference cancellation, and a detailed description of the interference cancellation process of the base station 100 will be omitted.

Then, the base station 100 ends the algorithm.

4 is a flowchart illustrating an operation of a terminal in a multi-user MIMO wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, in step 401, the MS determines whether a signal transmitted from the BS 100 is not received. Since the terminal confirms the resource allocation result through the message received from the base station 100, the terminal can recognize a period in which the signal to the self is not received.

If it is confirmed that the signal transmitted from the base station 100 is received, the terminal performs the process of step 401 again.

On the other hand, if it is confirmed that the signal transmitted from the base station 100 is not received, the terminal proceeds to step 403 to measure the interference channel and the interference signal. Herein, the interference channel means a channel value with the neighboring base station 100, and the interference signal means a signal from the neighboring base station 100, which means information used in the process of removing interference of a cell.

After measuring the interference channel and the interference signal, the terminal proceeds to step 405 and transmits the interference channel information and the interference signal information to the base station 100. Also, the terminal can transmit channel information with the base station 100. [

Thereafter, the MS proceeds to step 407 and performs an interference cancellation process. Herein, the interference cancellation process of the UE will be described. The interference cancellation process is performed by receiving the weight matrix information from the base station 100 and multiplying the received signal received from the base station 100 by the interference suppression matrix. Suppress interference. Then, the terminal may remove the interference by multiplying the reception signal multiplied by the interference suppression matrix by the weight matrix. The present invention relates to an algorithm for selecting user terminals to perform the interference cancellation, and a detailed description of the interference cancellation process of the terminal will be omitted.

Thereafter, the terminal terminates the algorithm.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but is capable of various modifications within the scope of the invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

1 schematically illustrates a multi-user MIMO wireless communication system in accordance with the present invention,

2 is a block diagram illustrating a configuration of a user selection unit in a multi-user MIMO wireless communication system according to an exemplary embodiment of the present invention.

3 is a flowchart illustrating an operation of a base station in a multi-user MIMO wireless communication system according to an exemplary embodiment of the present invention.

4 is a flowchart illustrating an operation of a terminal in a multi-user MIMO wireless communication system according to an exemplary embodiment of the present invention.

Claims (13)

A base station for interference cancellation in a multi-user MIMO wireless communication system, A calculation unit for receiving interference signal information from terminals and calculating an interference plus noise correlation matrix (INCM) index of all terminals in the cell using the received interference information; And a user selector for selecting a group of terminals to perform an interference cancellation process by comparing sizes calculated through the calculator, Wherein the calculation unit calculates the interference and noise correlation matrixes in at least one of a situation in which the channel states of the respective users are assumed to be similar on average and a situation in which the distribution of users is not uniformly distributed at a similar distance from the base station, And calculating an exponent. delete delete The method according to claim 1, The calculation unit may calculate, Wherein the interference and noise correlation matrix index is calculated using the following Equation (4), assuming that the channel states of the respective users are approximately the same.

here,

The interference and noise covariance matrix of the k-th user, HI, K is the interference channel of the k-th user, xI, K is the interference signal of the k-th user, and? The method according to claim 1, The calculation unit may calculate, And calculates the interference and noise correlation matrix index in a situation where the distribution of users is not uniformly distributed at a similar distance from the base station using Equation (5) below.

here,

Wherein H is an interference channel of the k-th user, K is an interference channel of the k-th user, xI and K are interference signals of the k-th user, Matrix. 5. The method of claim 4, The base station for interference cancellation in the multi-user MIMO- And selecting users having a small value of the interference and noise correlation matrix index so as to select users having a small influence of interference among users distributed at similar distances from the base station. 6. The method of claim 5, The base station for interference cancellation in the multi-user MIMO- Wherein the step of selecting an active set of users considering a path loss of a channel according to a distance of the base station selects users having a high value of the interference and noise correlation matrix index. A method for interference cancellation in a multi-user MIMO wireless communication system, Receiving interference signal information from terminals, Calculating interference and noise correlation matrix (INCM) indexes of all terminals in the cell using the received interference signal information;  And selecting a group of terminals to perform the interference cancellation process using the calculated interference and noise correlation matrix index, The interference and noise correlation matrix index, Wherein the calculation is performed in at least one of the following situations: assuming that the channel status of each user is on the average, and a situation in which the distribution of users is not uniformly distributed at a similar distance from the base station. delete 9. The method of claim 8, Wherein the interference and noise correlation matrix index is calculated using Equation (6) below, assuming that the channel states of the users are on average.

here,

Wherein R _Zk is a k-th user of the interference and noise covariance matrix, the H _{I, K} is the k-th user of the interference channel, the _{I x, K} is the k-th user of the interference signal, wherein σ means the noise power. 9. The method of claim 8, Wherein the interference and noise correlation matrix index is calculated using Equation (7) in a situation where the distribution of users is not uniformly distributed at a similar distance from the base station.

here,

Wherein R _Zk is a k-th user of the interference and noise covariance matrix, the H _{I, K} is the k-th user of the interference channel, the x _{I, K} is the interference signal k-th user, wherein σ is the noise power H _k is k Lt; th > user channel matrix. 11. The method of claim 10, Wherein the step of selecting a group of terminals to perform an interference cancellation process using the interference and noise correlation matrix index comprises: And selecting users having a small interference value and a noise correlation matrix index by selecting users having a small influence of interference among users distributed at similar distances from the base station. 12. The method of claim 11, Wherein the step of selecting a group of terminals to perform an interference cancellation process using the interference and noise correlation matrix index comprises: Selecting a set of active users considering a path loss of a channel according to a distance of the base station, and selecting users having a large value of the interference and noise correlation matrix index.

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