KR102001334B1 - Precoding method and base station for removing signal interference in full duplex communication - Google Patents

Abstract

Disclosed are a precoding method for removing a signal interference in full duplex communications and a base station performing the same. The disclosed full duplex base station for removing the signal interference between a half-duplex type uplink terminal and downlink terminal comprises: a channel estimation unit estimating channel coefficients between the base station, and the uplink terminals and the downlink terminals; a reception precoding matrix generation unit generating a reception precoding matrix based on a first code and a channel with the uplink terminal; and a transmission precoding matrix generation unit generating a transmission precoding matrix based on a second code orthogonal to the first code and a channel with the downlink terminal. The first code is used in generating a transmission signal of the uplink terminal and the second code is used for removing a transmission signal of the uplink terminal, including the first code, received as an interference signal when the downlink terminal receives a signal from the base station. The disclosed base station can efficiently remove the interference between the uplink terminal and the downlink terminal in a system including the full duplex type base station and the half duplex type user terminal.

Description

TECHNICAL FIELD [0001] The present invention relates to a precoding method for interference cancellation in a full-duplex communication and a base station performing the precoding method.

The present invention relates to a precoding method for interference cancellation in a full-duplex communication and a base station performing the precoding method. More particularly, the present invention relates to an up-link method of half duplex communication, which communicates with a full- And a precoding method for a technique for eliminating interference between a terminal and a down-link terminal.

Recently, due to explosive increase of mobile traffic, efforts are being made to increase the wireless transmission capacity of the mobile communication network.

Among them, Single-Channel Full-Duplex (FD) is attracting attention as an innovative communication method capable of greatly improving the radio transmission capacity.

In the current wireless communication system, a half-duplex scheme (Half-Duplex (HD)) in which one node performs only one operation of transmitting or receiving at a specific time-frequency is assumed, and the uplink transmission and the downlink transmission are separate Use radio resources.

On the other hand, in the full duplex scheme, a node can receive a different signal at the same time while transmitting a radio signal, and performs both uplink and downlink transmission using the same radio resource. Therefore, The capacity can be increased up to 2 times.

User terminals connected to the same cell in an existing wireless network use orthogonal radio resources such as different frequencies and time slots, so that there is no interference between them.

However, there is a problem in that even in the cell, interference may occur between the user terminals (the uplink terminal and the downlink terminal) in the wireless network based on the full duplex scheme, which is a half duplex scheme.

FIG. 1 is a schematic diagram illustrating a case where inter-terminal interference occurs in a communication in a general full-duplex scheme-based wireless network, and may include a plurality of user terminals and a base station (BS).

As shown in FIG. 1, when a base station (BS) communicates with an uplink terminal and a downlink terminal, uplink transmission and downlink reception are performed at the same frequency, It can act as an interference to the terminal.

If the uplink terminal and the downlink terminal are located at a short distance from each other, such interference can significantly affect wireless communication performance for transmitting and receiving wireless data.

Therefore, it is possible to stably perform wireless communication not only between terminals with a small interference in a full-duplex wireless communication network, but also between terminals having a possibility of interference between terminals, and in a full-duplex wireless communication, It is inevitable to develop a technology capable of efficiently performing communication between a plurality of terminals.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the related art, and it is an object of the present invention to provide a precoding method of a technique for eliminating interference between a UL terminal and a downlink terminal in a half duplex system communicating with a base station of a full duplex system.

According to an aspect of the present invention, there is provided a base station of a full duplex type for eliminating signal interference between a UL terminal and a DL terminal in a half duplex scheme, A channel estimator for estimating a channel coefficient between the base station, the uplink terminals and the downlink terminals; A reception precoding matrix generator for generating a reception precoding matrix based on a first code and a channel with the uplink terminal; And a transmission precoding matrix generator for generating a transmission precoding matrix based on a second code orthogonal to the first code and a channel with the downlink terminal, wherein the first code includes a transmission signal of the uplink terminal And the second code is used for removing the transmission signal of the uplink terminal, which includes the first code, which is received as an interference signal when the downlink terminal receives a signal from the base station A base station is provided.

Wherein the reception precoding matrix is an inverse matrix of a matrix having a multiplication of a channel coefficient between the base station and each uplink terminal and the first code as an element.

Wherein the transmission precoding matrix is an inverse matrix of a matrix having a multiplication of a channel coefficient between the base station and each downlink terminal and a complex conjugate of the second code as an element.

The transmission precoding matrix is generated using the following equation.

In the above equation, h _i is the channel coefficient between the base station and the i-th downlink terminal, C ₂ (1) and C ₂ (2) are the second code, and C ^* is the complex conjugate of C.

And the reception precoding matrix is generated using the following equation.

In the above equation, f _j is the channel coefficient between the base station and the j th uplink terminal, and C ₁ (1) and C ₁ (2) are the first codes.

And the base station transmits a signal using a number of subcarriers corresponding to the length of the first code or the second code.

An orthogonal code generator for generating an orthogonal code for eliminating signal interference between an uplink terminal and a downlink terminal; A code allocation unit allocating a first code of the orthogonal code to the uplink terminal and allocating a second code orthogonal to the first code of the orthogonal code to the downlink terminal; And an orthogonal code providing unit for providing the orthogonal code when scheduling the user terminal operating as the uplink terminal or the downlink terminal, wherein when the orthogonal code generated by the orthogonal code generating unit is 2, One identical first code is allocated to all uplink terminals and one identical second code is allocated to all downlink terminals.

The orthogonal code generator determines a length of the orthogonal code by reflecting the number of the uplink and downlink terminals. The orthogonal code generator generates the orthogonal code according to the number of orthogonal codes corresponding to the determined length, The first code and the second code are allocated according to the number of the first code and the second code.

When the uplink terminals are classified into a plurality of groups and a different first code is allocated to the plurality of groups, a second code assigned to the downlink terminal is allocated to all the first codes allocated to the plurality of groups And are orthogonal to each other.

Wherein the orthogonal code provider retransmits the orthogonal code and the allocation information to the user terminal when a change occurs in the orthogonal code and is updated.

According to another aspect of the present invention, there is provided a method for eliminating signal interference between a UL terminal and a DL terminal in a full duplex base station in a half duplex mode, Estimating a channel coefficient between the base station, the uplink terminals and the downlink terminals; And (b) generating a receive precoding matrix based on the first code and the channel with the uplink terminal; And (c) generating a transmit precoding matrix based on a second code orthogonal to the first code and a channel with the downlink terminal, wherein the first code is generated from a transmit signal of the uplink terminal And the second code is used for removing the transmission signal of the uplink terminal, which includes the first code, received by the downlink terminal as an interference signal when receiving the signal from the base station. Is provided.

Wherein the reception precoding matrix is an inverse matrix of a matrix having a multiplication of a channel coefficient between the base station and each uplink terminal and the first code as an element.

Wherein the transmission precoding matrix is an inverse matrix of a matrix having a multiplication of a channel coefficient between the base station and each downlink terminal and a complex conjugate of the second code as an element.

The transmission precoding matrix is generated using the following equation.

In the above equation, h _i is the channel coefficient between the base station and the i-th downlink terminal, C ₂ (1) and C ₂ (2) are the second code, and C ^* is the complex conjugate of C.

And the reception precoding matrix is generated using the following equation.

In the above equation, f _j is the channel coefficient between the base station and the j th uplink terminal, and C ₁ (1) and C ₁ (2) are the first codes.

And the base station transmits a signal using a number of subcarriers corresponding to the length of the first code or the second code.

According to still another embodiment of the present invention, there is provided a computer-readable recording medium on which a program for performing the precoding method is recorded.

According to an embodiment of the present invention, in a system including a full-duplex base station and a half-duplex user terminal, interference between an uplink terminal and a downlink terminal can be efficiently eliminated.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

FIG. 1 is a schematic diagram showing a case where inter-terminal interference occurs in a communication in a general full-duplex scheme-based wireless network.
FIG. 2 is a block diagram of a system for preventing inter-terminal signal interference in a full duplex system according to an embodiment of the present invention. Referring to FIG.
3 is a diagram for explaining a precoding process of a base station according to an embodiment of the present invention.
4 is a block diagram illustrating a configuration of a base station according to an embodiment of the present invention.
5 is a block diagram of a precoding matrix generator according to an embodiment of the present invention.
6 is a block diagram illustrating a configuration of an uplink terminal according to an embodiment of the present invention.
7 is a diagram illustrating generation and transmission of transmission signals of an uplink terminal according to an embodiment of the present invention.
8 is a block diagram illustrating a configuration of a downlink terminal according to an embodiment of the present invention.
9 is a diagram illustrating a process of removing an interference of a downlink terminal according to an embodiment of the present invention.
10 is a flowchart illustrating an operation of a base station according to an embodiment of the present invention.
11 is a flowchart illustrating an operation of an uplink terminal according to an embodiment of the present invention.
12 is a flowchart illustrating an operation of a downlink terminal according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" .

Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

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

FIG. 2 is a block diagram of a system for preventing inter-terminal signal interference in a full duplex system according to an embodiment of the present invention. Referring to FIG.

The present invention relates to a system (hereinafter referred to as a "full duplex system") including a base station 100 of a multi-user MIMO full duplex system and user terminals 300 and 400 transmitting or receiving signals in a half duplex system, The uplink terminal 200 and the downlink terminal 300 of the half duplex scheme use different codes (orthogonal codes) to transmit the uplink signal to the downlink terminal 300 It is an invention to reduce interference.

Hereinafter, an OFDM wireless communication system will be described as an embodiment of a full duplex system, but the wireless communication system according to another standard may be applied in the same manner.

The base station 100 of the full duplex system according to an embodiment of the present invention can generate an orthogonal code for eliminating signal interference between the uplink terminal 200 and the downlink terminal 300, A first code may be allocated to the terminal 200 and a second code of the orthogonal code may be allocated to the downlink terminal 300. [

That is, the first code and the second code are orthogonal codes orthogonal to each other. Hereinafter, the first code and the second code are referred to separately as necessary, or the first code and the second code are referred to as orthogonal codes.

The base station 100 may transmit the orthogonal code and the allocation information of the first code and the second code to the user terminals 300 and 400 when the resources are allocated to the user terminals 300 and 400 It can be transmitted at the time of scheduling.

The time point at which the base station 100 transmits the orthogonal code again may be when the orthogonal code changes (for example, the length of the orthogonal code changes).

Meanwhile, the uplink terminal 200 may generate a signal by multiplying (multiplying) a first code, which is an orthogonal code assigned by the base station 100, to a modulated symbol to be transmitted, As shown in FIG.

At this time, the uplink terminal 200 can transmit the generated signal in the number of time slots or subcarriers corresponding to the length of the first code.

That is, the generated signal can be transmitted to the base station 100 using a number of time slots corresponding to the length of the first code in the time domain and a number of subcarriers corresponding to the length of the first code in the frequency domain .

Hereinafter, an exemplary embodiment of transmitting the generated signal to the base station 100 in a number of time slots corresponding to the length of the first code will be described.

For example, if the length of the first code is 2, the uplink terminal 200 can transmit a signal to the base station 100 in the first time slot and the second time slot.

Conventionally, one signal is transmitted in one time slot. However, according to the present invention, since the signal is transmitted by extending the time axis according to the length of the orthogonal code, the number of users can be doubled by increasing the time axis.

Meanwhile, the downlink terminal 300 receives a signal transmitted from the base station 100 and an interference signal transmitted from the uplink terminal 200 transmitting a signal to the base station 100.

In this case, the interference signal of the uplink terminal 200 includes the first code, which is an orthogonal code, so that the downlink terminal 300 can transmit the interference signal to the uplink terminal 200 using the second code orthogonal to the first code It is possible to remove the interference signal caused by the interference.

Because the uplink terminal 200 transmits a signal in a number of time slots corresponding to the length of the first code, the interference signal from the uplink terminal 200 received by the downlink terminal 300 is also transmitted to the first May be received in a number of time slots corresponding to the length of the code.

Meanwhile, the base station 100 may apply a precoding matrix to the transmission signal and the reception signal for beamforming of the MIMO antenna. In this specification, a precoding matrix applied to a transmission signal of a base station will be referred to as a transmission precoding matrix, and a precoding matrix applied to a reception signal will be referred to as a reception precoding matrix.

3 is a diagram for explaining a precoding process of the base station 100 according to an embodiment of the present invention.

3 (a), the downlink terminal 300 multiplies the received signal by the second code to remove the interference signal from the uplink terminal 200, May precisely determine a transmit precoding matrix based on the channel with the downlink terminals 300 and the second code.

3B, since the base station 100 receives a signal including the first code from the uplink terminal 200, the base station 100 may transmit the signal including the first code to the pre- May determine a receive precoding matrix based on the channel with the uplink terminals 200 and the first code.

The base station 100 may transmit the generated signal in a number of time slots or subcarriers corresponding to the length of the orthogonal code.

As described above, the base station according to an embodiment of the present invention determines the transmit precoding matrix and the receive precoding matrix using the channel and the first code and the second code with the user terminals 200 and 300, The beamforming of the MIMO antenna of the base station can be effectively performed.

4 is a block diagram illustrating a configuration of a base station 100 according to an embodiment of the present invention.

The base station 100 according to an embodiment of the present invention includes an orthogonal code generator 110, a code allocator 120, an orthogonal code generator 130, a precoding matrix generator 160, a channel estimator 180 A control unit 140, and a storage unit 150. [0029]

The channel estimator 180 may estimate a channel coefficient between the base station and the user terminals 200 and 300. [ The channel coefficient between the base station and the uplink terminal 200 is used to calculate a reception precoding matrix at the reception precoding matrix generator 164 and the channel coefficient between the base station and the downlink terminal 300 is used to generate a transmission precoding matrix May be used to compute a transmit precoding matrix at portion < RTI ID = 0.0 > 162. < / RTI >

The orthogonal code generator 110 may generate an orthogonal code for eliminating signal interference between the uplink terminal 200 and the downlink terminal 300. At this time, the orthogonal code generation unit 110 may determine the length of the orthogonal code by reflecting the number of the uplink terminal 200 and the downlink terminal 300.

If the length of the orthogonal code is 2, the orthogonal code includes one first code assigned to the uplink terminal 200 and one second code assigned to the downlink terminal 300 (orthogonal to the first code) 1 ≪ / RTI >

In this case, all the uplink terminals 200 use the same first code, and all the downlink terminals 300 use the same second code.

The code allocation unit 120 may allocate a first code of the orthogonal code to the uplink terminal 200 and a second code orthogonal to the first code to the downlink terminal 300. [ Once the code allocation is completed, the orthogonal code is used as allocated, and the code allocation may not be performed at a specific point in time.

In one embodiment, when the length of the orthogonal code is 2, the code allocation unit 120 may allocate one first code and one second code to the uplink terminal 200 and the downlink terminal 300, respectively have.

In another embodiment, when the uplink terminals 200 are divided into three groups A, B, and C and the length of the orthogonal code is 4, the code assigning unit 120 assigns three different orthogonal codes to each other. 1 code, and the remaining one orthogonal code can be allocated to the A, B, and C groups, and the remaining one orthogonal code can be allocated to the downlink terminal 300 as a second code.

When asymmetry occurs in the number of uplink terminals 200 and the number of downlink terminals 400, the code allocation unit 120 allocates the number of uplink terminals 200 and the number of downlink terminals 400 ) ≪ / RTI >

Meanwhile, the orthogonal code providing unit 130 may provide an orthogonal code including a first code and a second code to the user terminal 300 or 400, and the providing time may be transmitted when resources are allocated, that is, .

For reference, the first code and the second code allocation information may be further transmitted together with the orthogonal code.

In addition, the orthogonal code providing unit 130 may retransmit the orthogonal code and the allocation information to the user terminals 300 and 400 when a change occurs in the orthogonal code such as a code length.

At this time, the orthogonal code providing unit 130 may transmit the orthogonal code and the allocation information to the newly added field in the previous stage of the existing subframe.

The precoding matrix generator 160 may generate a precoding matrix for beamforming of the MIMO antenna of the base station.

5 is a block diagram of a precoding matrix generator according to an embodiment of the present invention.

Referring to FIG. 5, the precoding matrix generator 160 may include a transmit precoding matrix generator 162 and a receive precoding matrix generator 164.

The transmit precoding matrix generator 162 may generate a transmit precoding matrix. The transmission precoding matrix may be determined in consideration of the interference cancellation process using the orthogonal code of the downlink terminal 300. [ That is, the transmission precoding matrix may be determined in consideration of the second code and the channel coefficient between the base station and the downlink terminal 300. The signal after the i < th > downlink terminal 300 removes the interference using the second code is expressed by Equation (1).

In Equation (1), r _i is a signal after the i-th downlink UE removes the interference, h _i is the channel coefficient of the BS and the i-th downlink UE, x (1) and x , C ₂ (1) and C ₂ (2) are the second code, and C ^* is the conjugate complex number of C.

Therefore, the signal after eliminating the interference of the entire downlink terminal is expressed by Equation (2).

In Equation (2), K _d is the total number of downlink terminals 300.

Therefore, the transmission signal of the base station for allowing the entire downlink terminal 300 to obtain a desired signal after interference cancellation is expressed by the following equation.

In Equation (3), [H ^-1 ] _i denotes an i-th row vector of H ^-1 , and r _i denotes a signal to be obtained after interference cancellation by the i-th downlink terminal 300.

Therefore, the transmit precoding matrix can be determined as shown in Equation (4) below.

That is, the transmission precoding matrix may be calculated as an inverse matrix of a matrix having a multiplication of a channel coefficient between a base station and each downlink terminal 300 and a complex conjugate of a second code as elements.

The reception precoding matrix generator 164 may generate a reception precoding matrix. The reception precoding matrix may be determined in consideration of the transmission signal of the uplink terminal 200. That is, the reception precoding matrix may be determined in consideration of the first code and the channel coefficient between the base station and the uplink terminal 200.

The reception signal of the base station received from the overall uplink terminal 200 is expressed by Equation (5).

In Equation 5, v (1), and v (2) is a received signal of the base station, f _j is a channel coefficient between the j-th UL terminal 200 and the base station, C ₁ is the first code, s _j Is a signal to be transmitted by the j-th uplink terminal 200, and K _u is the number of all uplink terminals 200.

Therefore, the signal to be transmitted from the UL terminal 200 can be calculated using the following equation (6).

Therefore, the reception precoding matrix can be determined as shown in Equation (7).

That is, the reception precoding matrix may be calculated as an inverse matrix of a matrix having a multiplication of a first code and a channel coefficient between the base station and each of the uplink terminals 200 as an element.

The control unit 140 includes elements of the base station 100 such as an orthogonal code generating unit 110, a code assigning unit 120, an orthogonal code providing unit 130, a precoding matrix generating unit 160, And the channel estimation unit 180 to perform the above-described operations.

Meanwhile, the storage unit 150 may store an algorithm for allowing the controller 140 to control the components of the base station 100 and various data required or derived in the control process.

The base station 100 may include only a precoding matrix generator 160, a channel estimator 180, a controller 140, and a storage unit 150 as another embodiment of the present invention. The base station 100 may not include the orthogonal code generator 110, the code allocator 120, and the orthogonal code generator 130. In this case, The orthogonal codes can be preset and stored.

FIG. 6 is a block diagram illustrating a configuration of an uplink terminal according to an embodiment of the present invention, and FIG. 7 is a diagram illustrating generation and transmission of a transmission signal of an uplink terminal according to an embodiment of the present invention.

The uplink terminal 200 according to an exemplary embodiment of the present invention may include a transmission signal generator 210, a signal transmitter 220, a controller 230, and a memory 240.

The transmission signal generating unit 210 generates a signal using the first code C1 for allowing the downlink terminal 300 to remove the interference due to the transmission signal of the downlink terminal 300 .

Specifically, when a modulated symbol containing information for transmitting the transmission signal of the j-th uplink terminal 200 to the base station 100 by x _uj (t) and the j-th uplink terminal 200 is s _uj , The transmission signal generated by the transmission signal generating unit 210 during the L symbol by applying the first code C ₁ can be expressed by Equation (8) below.

The process of generating and transmitting a transmission signal by the uplink terminal 200 is illustrated in FIG.

The signal transmission unit 220 may transmit the transmission signal generated by the transmission signal generation unit 210 to the base station 100.

At this time, the signal transmitting unit 220 can transmit the generated signal in a number of time slots corresponding to the length of the first code (C ₁ ).

이라고 하면, 상기 [수학식 8]에 의해 송신 신호는 아래의 [수학식 9]와 같이 나타낼 수 있다.For example, when the symbol is 2 (L = 2), the first code

, The transmission signal can be expressed by the following equation (9) by the above-mentioned equation (8).

Here, K _u is the number of uplink users, and (1) and (2) on the left can be subcarriers or time for transmitting signals.

Thus, the first time slot and transmits a x c ₁₁ · s at _{uj uj} (1), it is possible to transfer c ₂₁ · s _uj 2 in time slot x _uj (2).

Conventionally, one signal is transmitted in one time slot. However, according to the present invention, since the signal is transmitted by extending the time axis according to the length of the code, the number of users can be doubled by increasing the time axis.

Meanwhile, when the uplink terminal 200 generates a signal using the first code (C ₁ ), which is an orthogonal code, and transmits the signal to the base station 100, the controller 230 controls the time corresponding to the length of the first code For example, the transmission signal generator 210 and the signal transmitter 220 to perform the above-described operation so as to transmit a signal in the slot of the uplink terminal 200, It can also be controlled.

Meanwhile, the memory 240 may store an algorithm for controlling the components of the uplink terminal 200 by the control unit 230 and various data required or derived in the control process.

FIG. 8 is a block diagram illustrating a configuration of a downlink terminal according to an embodiment of the present invention, and FIG. 9 is a diagram illustrating an interference cancellation process of a downlink terminal according to an embodiment of the present invention.

The downlink terminal 300 according to an embodiment of the present invention may include a signal receiving unit 310, an interference signal removing unit 320, a control unit 330, and a memory 340.

The signal receiving unit 310 may receive a signal from the base station 100 and may receive a part of the signals transmitted from the uplink terminal 200 to the base station 100 .

This is because the uplink terminal 200 and the downlink terminal 300 transmit or receive signals in a half duplex mode while the base station 100 operates in full duplex mode.

The signal received by the signal receiving unit 310 can be expressed by Equation (10).

Here, u (t) is the signal received by the downlink terminal 300 at time t, h is the channel coefficient between the base station 100 transmitter 110 and the downlink terminal 300, and W _d is the beamforming K _d is the number of downlink terminals 300 and S _d is a modulated symbol containing information to be transmitted from the base station 100 to the downlink terminal 300, digital pre-coding matrix for the S _d of the base station 100 for beam-forming, K _u is the number of uplink terminal 200, g _ji is the j-th UL terminal 200 and the i-th DL terminal (300 , X _u is the transmission signal of the uplink terminal 200, and n (t) is the noise of the downlink terminal 300.

A signal received at the signal receiving unit 310 of the downlink terminal 300 during the L symbol can be expressed by Equation (11) below.

If Equation (8) is applied to Equation (11), it can be expressed as Equation (12) below.

Here, it can be confirmed that the 'first code C ₁ ' is reflected in the signal transmitted to the downlink terminal 300 among the signals transmitted from the uplink terminal 200 to the base station 100.

The interference signal remover 320 receives the interference signal as the signal of the uplink terminal 200 in the signal received by the signal receiver 310, that is, the signal transmitted from the uplink terminal 200 to the base station 100 The signal received by the downlink terminal 300 can be removed.

The interference signal canceling unit 320 uses a second code (hereinafter, referred to as an orthogonal code) C _{2 that} is a code orthogonal to the code C ₁ of the uplink terminal 200 The interference signal due to the uplink terminal 200 included in the signal can be removed and expressed by Equation (13).

In Equation (13), it can be confirmed that the corresponding interference signal is removed by inserting the orthogonal code C ₂ into the interference signal by the uplink terminal 200.

이라고 하면, 제1 코드에 직교하는 제2 코드(C₂)는

와 같이 나타낼 수 있다.For reference, when the length of the first code (C ₁ ) is 2 when the embodiment described while explaining the uplink terminal 200

, The second code (C ₂ ) orthogonal to the first code is

As shown in Fig.

The process of removing the interference signal by the uplink terminal 200 in the downlink terminal 300 is illustrated in FIG.

Meanwhile, the controller 330 controls the components of the downlink terminal 300, for example, the downlink terminal 300 to remove the interference signal from the uplink terminal 200 using the orthogonal code C ₂ . The signal receiving unit 310, the interference signal removing unit 320, and the memory 340. [

Meanwhile, the memory 340 may store various data required or derived in an algorithm and a control process for the control unit 330 to control the elements of the downlink terminal 300.

10 is a flowchart illustrating an operation of the base station 100 according to an embodiment of the present invention.

The base station 100 generates an orthogonal code of a specific length by reflecting the number of the uplink terminal 200 and the downlink terminal 300 (S801).

After step S801, the base station 100 allocates the first code of the orthogonal codes to the uplink terminal 200 and allocates the second code of the orthogonal codes to the downlink terminal 300 (S802).

After step S802, the base station 100 provides an orthogonal code at the time of resource allocation, i.e., scheduling, to a user terminal operating as an uplink terminal or a downlink terminal (S803).

At this time, allocation information of the first code and the second code may be further provided.

After S803, the base station 100 estimates a channel coefficient with each of the terminals (S804).

After S804, the base station 100 generates a precoding matrix based on the orthogonal code and the channel coefficient (S805).

11 is a flowchart illustrating an operation of an uplink terminal according to an embodiment of the present invention.

The uplink terminal 200 generates a signal to be transmitted to the base station 100 during L symbols. At this time, the downlink terminal 300 generates a signal using the first code (C ₁ ) for eliminating the interference caused by the transmission signal of the base station 300 (S901).

The first code C ₁ is orthogonal to the second code C ₂ , which is an orthogonal code assigned to the downlink terminal 300.

After S901, the uplink terminal 200 transmits the generated signal to the base station 100 in the time slot corresponding to the length of the orthogonal code (S902).

12 is a flowchart illustrating an operation of a downlink terminal according to an embodiment of the present invention.

The downlink terminal 300 receives the signal transmitted from the base station 100 and the interference signal transmitted from the uplink terminal 200 transmitting the signal to the base station 100 (S1001).

After step S1001, the downlink terminal 300 removes the interference signal from the uplink terminal 200 using the second code (C ₂ ), which is an orthogonal code orthogonal to the first code (C ₁ ) included in the interference signal (S1002).

The above-described technical features may be implemented in the form of program instructions that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media 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 machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules to perform the operations of the embodiments, and vice versa.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

100: base station
110: orthogonal code generating unit, 120: code assigning unit, 130: orthogonal code providing unit
140: control unit, 150: storage unit 160: precoding matrix generation unit
162: Transmission precoding matrix generator 164: Receive precoding matrix generator
180: channel estimation unit
200: Uplink terminal
210: Transmission signal generation unit, 220: Signal transmission unit
230: control unit, 240: memory
300: Downlink terminal
310: Signal receiving unit, 320: Interference signal removing unit
330: control unit, 340: memory

Claims (17)

1. A base station of a full duplex system for eliminating half-duplex signal interference between an uplink terminal and a downlink terminal,
A channel estimator for estimating a channel coefficient between the base station, the uplink terminals and the downlink terminals;
A reception precoding matrix generator for generating a reception precoding matrix based on a first code and a channel with the uplink terminal; And
A transmission precoding matrix generator for generating a transmission precoding matrix based on a second code orthogonal to the first code and a channel with the downlink terminal,
Wherein the first code is used for generating a transmission signal of the uplink terminal,
The second code is used to remove the transmission signal of the uplink terminal, which includes the first code, received by the downlink terminal as an interference signal when receiving the signal from the base station,
Wherein the reception precoding matrix is an inverse of a matrix having a multiplication of a channel coefficient between the base station and each uplink terminal and the first code as elements.
delete The method according to claim 1,
Wherein the transmit precoding matrix is an inverse of a matrix having a multiplication of a channel coefficient between the base station and each downlink terminal and a complex conjugate of the second code as an element. The method according to claim 1,
Wherein the transmit precoding matrix is generated using the following equation.

In the above equation, h _i is the channel coefficient between the base station and the i-th downlink terminal, C ₂ (1) and C ₂ (2) are the second code, and C ^* is the complex conjugate of C. The method according to claim 1,
Wherein the receive precoding matrix is generated using the following equation.

In the above equation, f _j is the channel coefficient between the base station and the j th uplink terminal, and C ₁ (1) and C ₁ (2) are the first codes. The method according to claim 1,
Wherein the base station transmits a signal using a number of subcarriers corresponding to the length of the first code or the second code. The method according to claim 1,
An orthogonal code generator for generating an orthogonal code for eliminating signal interference between an uplink terminal and a downlink terminal;
A code allocation unit allocating a first code of the orthogonal code to the uplink terminal and allocating a second code orthogonal to the first code of the orthogonal code to the downlink terminal; And
Further comprising an orthogonal code providing unit for providing the orthogonal code to a user terminal operating as the uplink terminal or the downlink terminal upon scheduling,
When there are two orthogonal codes generated by the orthogonal code generation unit,
The code assigning unit
Allocates one identical first code to all uplink terminals,
And allocates one identical second code to all downlink terminals. 8. The method of claim 7,
The orthogonal code generation unit
Determines the length of the orthogonal code by reflecting the number of the uplink terminal and the downlink terminal,
The code assigning unit
And allocates the first code and the second code according to the number of the uplink terminal and the downlink terminal in the number of orthogonal codes corresponding to the determined length. 8. The method of claim 7,
When the uplink terminals are classified into a plurality of groups and different first codes are allocated to the plurality of groups,
Wherein the second code assigned to the downlink terminal is orthogonal to all the first codes assigned to the plurality of groups. 8. The method of claim 7,
The orthogonal code providing unit,
And the orthogonal code and the allocation information are retransmitted to the user terminal when the orthogonal code changes and is updated. A method for eliminating signal interference between a UL terminal and a DL terminal in a full duplex base station half duplex system,
(a) estimating a channel coefficient between the base station, the uplink terminals and the downlink terminals; And
(b) generating a receive precoding matrix based on the first code and the channel with the uplink terminal; And
(c) generating a transmit precoding matrix based on a second code orthogonal to the first code and a channel with the downlink terminal,
Wherein the first code is used for generating a transmission signal of the uplink terminal,
The second code is used to remove the transmission signal of the uplink terminal, which includes the first code, received by the downlink terminal as an interference signal when receiving the signal from the base station,
Wherein the reception precoding matrix is an inverse of a matrix having a multiplication of a channel coefficient between the base station and each of the uplink terminals and the first code as elements.
delete 12. The method of claim 11,
Wherein the transmit precoding matrix is an inverse of a matrix having a multiplication of a channel coefficient between the base station and each downlink terminal and a complex conjugate of the second code as an element. 12. The method of claim 11,
Wherein the transmit precoding matrix is generated using the following equation.

In the above equation, h _i is the channel coefficient between the base station and the i-th downlink terminal, C ₂ (1) and C ₂ (2) are the second code, and C ^* is the complex conjugate of C. 12. The method of claim 11,
Wherein the reception precoding matrix is generated using the following equation.

In the above equation, f _j is the channel coefficient between the base station and the j th uplink terminal, and C ₁ (1) and C ₁ (2) are the first codes. 12. The method of claim 11,
Wherein the base station transmits a signal using a number of subcarriers corresponding to the length of the first code or the second code. 12. A computer-readable recording medium on which a program for performing the precoding method of claim 11 is recorded.

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