KR101935648B1 - Method and Device for Determining SNR loss rate and Designing Precoder Considering Desired PAR - Google Patents

Abstract

A method and apparatus for SNR loss rate determination and precoder design considering a target PAR are disclosed. The disclosed method includes: (a) designing a null-space precoder associated with a beam to be transmitted in a null space and a real power precoder associated with a beam that is effectively transmitted to receivers using an estimated channel; (B) designing an integrated precoder by determining an SNR loss factor to be applied to the active power precoder and a null space power adjustment matrix to be applied to the null space precoder; And (c) determining an SNR loss rate to be applied to each receiver based on the SNR loss rate, wherein the SNR loss ratio and the null space power adjustment matrix are determined through convex optimization so that the SNR loss rate is minimized while the target PAR is fixed And an SNR loss rate to be applied to each receiver is determined using channel quality information with each receiver and QoS required for each receiver. According to the disclosed invention, there is an advantage that the SNR loss rate can be minimized while satisfying the target PAR in the multi-antenna system.

Description

Field of the Invention [0001] The present invention relates to SNR loss rate determination and pre-coder design method and apparatus considering target PAR,

Embodiments of the present invention are directed to a method and apparatus for SNR loss rate determination and precoder design that takes into account a target PAR.

As a waveform technology of the next generation 5G mobile communication system, techniques such as FBMC, GFDM and UFMC which have relatively high complexity but high frequency efficiency are being discussed, and OFDM-based (Orthogonal Frequency Division Multiplexing) Is also being actively discussed. However, in the OFDM scheme, nonlinear signal distortion occurs if the dynamic range of the power amplifier is not sufficiently ensured because the peak-to-average power ratio (PAR) is high.

Currently, research and development is underway on technologies to reduce PAR in OFDM, and these technologies can be largely divided into nonlinear and linear methods. Nonlinear methods include clipping, clipping & filtering, peak windowing, and peak cancellation. Linear methods include Selective Mapping (SLM), Partial Transmit Sequence (PTS), and peak windowing.

The clipping technique is basically easy to implement and has a low hardware complexity. However, there is a problem that nonlinear distortion occurs. This nonlinear distortion causes EVM (Error Vector Magnitude) deterioration at the in-band of the OFDM signal and out-band emission for the adjacent band at the out-band And the spectrum performance deteriorates.

In addition to the clipping technique, techniques such as SLM (selective mapping), PTS (partial transmit sequence), and tone reservation techniques exist. However, these methods also have a problem in that linear distortion occurs, has a large complexity, and can not appropriately utilize spatial resources.

On the other hand, nonlinear signal distortion can be avoided by using power resources in consideration of necessary back-off according to the specifications of the power amplifier mounted on the transmitter. However, this approach can be a major factor in greatly reducing transmit coverage.

 Also, for effective high capacity data transmission, it is highly probable that a data transmission / reception method using multiple input multiple output (MIMO) is also used in a low delay / ultra high speed data transmission / reception technique. However, if the MIMO precoding scheme is applied to the OFDM system, the PAR performance becomes worse.

The present invention proposes a SNR loss rate determination and precoder design method and apparatus applicable to a multi-antenna system while satisfying a target PAR.

According to an aspect of the present invention, there is provided a method comprising: (a) designing a null-space precoder associated with a beam to be transmitted in a null space and a real power precoder associated with a beam that is effectively transmitted to receivers using an estimated channel; (B) designing an integrated precoder by determining an SNR loss factor to be applied to the active power precoder and a null space power adjustment matrix to be applied to the null space precoder; And (c) determining an SNR loss rate to be applied to each receiver based on the SNR loss rate, wherein the SNR loss ratio and the null space power adjustment matrix are determined through convex optimization so that the SNR loss rate is minimized while the target PAR is fixed And an SNR loss rate to be applied to each receiver is determined based on channel quality information of each receiver and a target PAR determined using QoS required for each receiver.

) 및 영 공간 파워 조절 매트릭스는 다음의 컨벡스 최적화를 통해 결정된다. The SNR loss rate (

) And the null space power control matrix are determined by the following convex optimization.

는 역 푸리에 변환 행렬을 의미함.In the above equation, t is a vector constituting the space power modulation matrix T, d is a data stream, and K is the total number of subcarriers.

Denotes an inverse Fourier transform matrix.

The step (c) applies a relatively low SNR loss rate to a receiver with a good channel quality and a low required QoS and applies a relatively high SNR loss rate to a receiver with a bad channel quality and a high required QoS.

)는 상기 추정된 채널에 대한 SVD에 의해 획득되는 매트릭스

및

를 이용하여 다음의 수학식과 같이 설계된다. The active power precoder (

) Is a matrix obtained by SVD for the estimated channel

And

Is designed using the following equation.

In the above equation, the subscript k is an index representing a subcarrier, and the subscript j is an index representing a receiver.

)는

의 영 공간을 생성하는 기저벡터 들 중 c_j개의 기저벡터로 이루어진 일열 매트릭스인

와 상기 추정된 채널에 대한 SVD에 의해 획득되는 매트릭스

를 이용하여 다음의 수학식과 같이 설계된다. The zero space pre-coder (

)

Of the base vectors generating the null space of c _j

And a matrix obtained by the SVD for the estimated channel

Is designed using the following equation.

In the above equation, R denotes a reception filter of a receiver, H denotes an estimated channel, a superscript j denotes a receiver index, and a subscript k denotes a subcarrier index.

The integrated precoder (F) to which the determined SNR loss rate and the null space power adjustment matrix T are applied is designed according to the following equation.

는 유효 전력 프리코더를 의미하고,

는 영 공간 프리코더를 의미함. In the above equation,

Quot; means an active power precoder,

Means a zero-space precoder.

) 및 영 공간 파워 조절 매트릭스는 다음의 추가적인 조건을 고려하여 컨벡스 최적화를 통해 결정된다. The SNR loss rate (

) And the zero space power control matrix are determined through the convex optimization taking into account the following additional conditions.

는 역 푸리에 변환 행렬을 의미하고,

는

를 만족하는

를 원소로 하는 대각 매트릭스이고, M은 송신기의 안테나 수이며,

는 목표 PAR을 의미하고,

는 심볼의 송신 전력을 의미하며, t는 영 공간 파워 조절 매트릭스를 구성하는 벡터이며, b는 다음의 수학식과 같이 정의되며, In the above equation,

Denotes an inverse Fourier transform matrix,

The

Satisfy

Where M is the number of antennas of the transmitter,

Means the target PAR,

T denotes a transmission power of a symbol, t denotes a vector constituting a zero space power control matrix, b denotes a following equation,

및

는 추정된 채널에 대한 SVD를 이용하여 획득되는 매트릭스이고,

는 송신 신호 벡터임.

And

Is a matrix obtained using the SVD for the estimated channel,

Is a transmission signal vector.

According to another aspect of the present invention there is provided an active power precoder comprising: a real power precoder designing unit for designating a real power precoder associated with a beam that is effectively transmitted to receivers using an estimated channel; A zero space pre-coder designing a zero space pre-coder associated with the beam transmitted to the zero space; An integrated precoder designing unit for designating an integrated precoder by determining an SNR loss rate to be applied to the active power precoder and a null space power adjustment matrix to be applied to the null space precoder; And an SNR loss rate determination unit for each receiver that determines an SNR loss rate to be applied to each receiver based on the SNR loss rate, wherein the SNR loss rate and the null space power adjustment matrix are determined by performing convex optimization so that the SNR loss rate is minimized while the target PAR is fixed And an SNR loss rate to be applied to each receiver is determined based on channel quality information of each receiver and a target PAR determined using QoS required for each receiver.

According to the present invention, there is an advantage that the SNR loss rate can be minimized while satisfying the target PAR in the multi-antenna system.

FIG. 1 is a block diagram illustrating a structure of a multi-user MIMO-OFDM system to which an SNR loss rate determination and precoder design method considering a target PAR according to an embodiment of the present invention is applied.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method and apparatus for setting a precoder and an SNR loss rate,
FIG. 3 is a conceptual structure of an integrated precoder according to the present invention; FIG.
FIG. 4 is a block diagram illustrating a structure of an SNR loss rate and precoder designing apparatus considering a target PAR according to an embodiment of the present invention; FIG.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

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

1 is a block diagram illustrating a structure of a multi-user MIMO-OFDM system to which an SNR loss rate determination and precoder design method considering a target PAR according to an embodiment of the present invention is applied.

인 경우,

이고,

이면,

의 관계를 가질 수 있다. 1, a communication system to which a method according to an embodiment of the present invention is applied includes a transmitter having a plurality of (M) antennas and a plurality (J) of receivers having a plurality of (N) . At this time,

Quot;

ego,

If so,

. ≪ / RTI >

Inverse Fourier Transform (IDFT) conversion is performed for each transmit antenna, and P / S conversion and CP (Cyclic Prefix) addition are performed for each transmit antenna after IDFT conversion.

In addition, S / P conversion and CP removal are performed for each receiver, and DFT (Discrete Fourier Transform) conversion is performed on the signal from which the CP is removed. There is a feedback channel between the transmitter and the receiver that feeds back the estimated channel information.

개의 데이터 스트림이 실려 있는 신호 벡터

를 k번째 부반송파를 통해 j번째 수신기에 전송한다. 여기서 신호벡터

는 QAM 변조 신호를 포함할 수 있다. 이때,

을 만족한다. 여기서, k는 서브 캐리어를 의미하는 인덱스이고, j는 수신기를 의미하는 인덱스이다. The transmitter

Signal vectors carrying data streams

To the jth receiver through the kth subcarrier. Here,

May comprise a QAM modulated signal. At this time,

. Here, k is an index indicating a subcarrier, and j is an index indicating a receiver.

는 송신기와 j번째 수신기 사이의 채널 매트릭스로 정의된다. 또한, j번째 수신기를 위한 k번째 서브캐리어의 프리코딩 매트릭스는

로 정의되고, k번째 서브케리어의 j번째 수신기의 수신 필터는

로 정의되며, 잡음 벡터는

으로 정의된다.

Is defined as the channel matrix between the transmitter and the jth receiver. Further, the precoding matrix of the k < th > subcarrier for the j < th &

, And the reception filter of the j < th > receiver of the k < th &

, And the noise vector is defined as

.

The reception signal for each subcarrier of the j-th receiver can be defined as Equation (1).

는

와 같이 정의될 수 있으며, 이는 각 수신기별 QAM 신호의 집합으로 정의될 수 있을 것이다. 또한, 서브 캐리어별 프리코더

는

로 정의될 수 있으며, 이는 각 서브캐리어에 대한 프리코딩 매트릭스들의 집합으로 정의될 수 있을 것이다. 각 신호벡터에 프리코더가 적용되므로, 안테나를 통해 송신되는 신호는

로 정의될 수 있을 것이다. 본 실시예에서는 모든

에 대해

를 만족한다는 것을 가정한다. On the other hand, the subcarrier-

The

, Which may be defined as a set of QAM signals for each receiver. Further, the subcarrier-

The

, Which may be defined as a set of precoding matrices for each subcarrier. Since the precoder is applied to each signal vector, the signal transmitted through the antenna is

. In this embodiment,

About

≪ / RTI >

Here, I is the identity matrix and Ps is the power of the transmission symbol.

와

및

로 정의한다. To represent one vector or matrix for all subcarriers

Wow

And

.

의 모든 원소들은 그림 1의 재배열 블록(reordering block)에서 일대일 대응 행렬

를 통해서 다음과 같이 M개의 송신 안테나를 통해서 전송된다.

.

는 i번째 안테나를 통해서 전송되는 주파수 축 신호를 의미하고, 이에 상응하는 시간 축 신호 벡터를

으로 나타낸다. 이때,

이다.

는 역 푸리에 변환 행렬이고, 블록 대각행렬

를 구성한다.vector

All the elements of the reordering block of Fig.

Through M transmit antennas as follows.

.

Denotes a frequency-axis signal transmitted through an i-th antenna, and a corresponding time-axis signal vector

Respectively. At this time,

to be.

Is an inverse Fourier transform matrix, and a block diagonal matrix

.

PAR is an index indicating the ratio of the average power to the maximum power. When the PAR is large, the distortion of the signal may occur due to a problem of deviating from the linear amplification section of the power amplifier.

The PAR for the signal transmitted from the i < th > antenna of the transmitter can be defined as Equation (2).

, 즉 재배열 블록의 일대일 대응 매트릭스가 아이덴터티(Identity) 매트릭스라고 가정한 것이다. On the other hand, the PAR for all antennas of the transmitter can be approximated as shown in Equation (3), and the approximation of Equation

, That is, a one-to-one correspondence matrix of the rearrangement block is an identity matrix.

2 is a flowchart illustrating an overall flow of a precoder and an SNR loss rate setting method considering a target PAR according to an embodiment of the present invention.

Referring to FIG. 2, a first active power precoder and a null space pre-coder for an integrated precoder are designed (step 200). Here, the integrated precoder means a precoder for all users and subcarriers.

In the present embodiment, the use of the precoder proposed by the inventor of the present invention is presupposed. Further details of the precoder according to the present invention are described in detail in the Patent No. 10-1500882 of the inventor of the present invention And the contents of the patent may be referred to for the understanding of the present invention.

3 is a diagram illustrating a conceptual structure of an integrated precoder according to the present invention.

The integrated precoder proposed by the present inventor includes an active power precoder 300 for the beam delivered to the target receiver for PAR control and a null space precoder 310 for transmitting the beam in the null space .

) 중

에 해당되는 유효 전력비가 적용되고, 영공간 프리코더(310)에는 향후 결정하게 되는 영공간 파워 조절 매트릭스가 적용된다. 여기서 영공간(Null Space)는 수신기들에 간섭을 미치지 않는 공간을 의미한다. 즉, 본 발명의 일 실시예에 따른 프리코더는 유효 전력의 빔을 수신기를 향해 전송하도록 하고 일부의 빔에 대해서는 간섭이 없는 영 공간으로 전송하도록 빔포밍을 수행하는 것이다. In the active power precoder 300, the SNR loss rate (1-

) Of

And the zero space power control matrix to be determined in future is applied to the null space precoder 310. [ Here, the null space means a space that does not interfere with the receivers. That is, the precoder according to an embodiment of the present invention performs beamforming so as to transmit a beam of active power toward a receiver and transmit the beam to a zero space free of interference for some beams.

로 정의하고 영공간 프리코더(310)는

로 정의한다. 본 발명의 통합 프리코더는 다음의 수학식 4와 같이 표현될 수 있다. In this embodiment, the active power precoder 300

And the null space precoder 310 defines

. The integrated precoder of the present invention can be expressed as the following Equation (4).

)에 곱해지는

는 유효 전력비에 해당되며, SNR 손실율은 (1-

)로 표현할 수 있다. 영공간 프리코더(

)에 곱해지는 T는 영공간으로의 파워 조절 매트릭스이다. 영공간으로의 파워 조절을 위한 변수 매트릭스인 T는 특정 서브캐리어(k)에 대해

로 정의될 수 있다. Active power precoder (

)

Corresponds to the effective power ratio, and the SNR loss rate corresponds to (1-

). Young Space PreCoder (

) Is the power control matrix to the null space. T, which is a variable matrix for power adjustment to the null space, is defined for a particular subcarrier (k)

. ≪ / RTI >

The active power precoder 300 designes using the estimated channel information. According to a preferred embodiment of the present invention, the estimated channel is represented by SVD (Singular Value Decomposition).

가 정의된다.

매트릭스는 유효 채널인

의 최대 고유값(Eigen value) 방향의 벡터들로 이루어진다.

역시 SVD를 통해 획득되는 매트릭스이다.

와 관계가 성립할 때,

는

의 처음

개의 열벡터로 이루어지는 매트릭스로 정의될 수 있을 것이다. A matrix consisting of column vectors for basis vectors that produce the null space of a channel when representing a channel by SVD

Is defined.

The matrix is the effective channel

And a vector in the direction of the maximum eigenvalue.

It is also a matrix obtained through SVD.

When the relationship is established,

The

The beginning of

Lt; RTI ID = 0.0 > matrix. ≪ / RTI >

및

를 이용하여 사용자(j)별 유효 전력 프리코딩 매트릭스는

로 정의되며, 유효 전력 프리코더는 다음의 수학식 5와 같이 정의된다. Defined

And

Lt; RTI ID = 0.0 > (j) < / RTI >

, And the active power precoder is defined by the following Equation (5).

의 영 공간을 생성하는 기저벡터 들 중 c_j개의 기저벡터로 이루어진 일열 매트릭스인

를 정의한다. For the design of a binary, zero-space precoder

Of the base vectors generating the null space of c _j

.

로 정의되며, 영 공간 프리코더는 다음의 수학식 6과 같이 정의된다. The null space precoding matrix for each receiver (j) constituting the null space precoder is

And the null space precoder is defined as Equation (6).

)와 영공간으로의 파워 조절을 위한 변수에 대한 매트릭스 T를 결정한다(단계 202). As such, if the null space precoder and the active power precoder are individually designed, the SNR loss rate to be applied to the integrated precoder

And a matrix T for a variable for power adjustment to the null space (step 202).

라고 할 때,

의 관계가 성립한다. 컨벡스 최적화 문제를 구성하기 위해 하나의 매트릭스 또는 벡터로 표현하면 다음의 수학식 7 내지 수학식 9와 같이 표현될 수 있다. (A signal to which the precoder is applied to the QAM modulation signal)

When you say,

. In order to construct the convex optimization problem, a matrix or a vector may be expressed by the following equations (7) to (9).

The vector t in Equation (9) is a variable determined by the design. The denominator of PAR _L defined in Equation (3) can be expressed as Equation (10) with respect to the vector t.

에 대한 함수로 근사화될 수 있으며, 근사화된 PAR은 다음의 수학식 11과 같이 정의될 수 있다. Then PAR _L is the vector t, which is the element of the matrix T for the variable for power adjustment to the null space

, And the approximated PAR can be defined as: < EMI ID = 11.0 >

If the SNR loss rate is set to any fixed value, the possible range of t can be defined as a convex ball. In this case, the approximated PAR can be defined by the following Equation (12), and Equation (12) holds when the SNR loss rate is arbitrarily fixed and K is a natural number which is very large.

로 정의하고,

로 설정하며, 선형 근사화를 통해

를 고려한다. The required PAR value

Respectively,

, And by linear approximation

.

) 및 영공간으로의 파워 조절 매트릭스인 T를 구하기 위한 컨벡스 최적화는 다음의 수학식 13과 같이 정의될 수 있다. In this way, in a state in which the required PAR value is fixed, the SNR loss rate (1-

) And the power control matrix T for the null space can be defined as Equation (13). &Quot; (13) "

)을 최소화하면서 영 공간으로의 파워 조절 매트릭스인 T를 구성하는 벡터 t에 대해

의 구속 조건 및

구속 조건 하에서 목표 PAR을 만족하면서 최소화된 수신 SNR 손실율 (1-

)을 컨벡츠 최적화를 통해 구하는 것이다. As a result, the received SNR loss rate (1-

) For the vector t constituting the power control matrix T for the null space

And

Under constrained conditions, the received SNR loss rate (1-

) Through context optimization.

를 찾고

를

같이 분할하여 K개의 벡터를 찾는다. 모든 k에 대해 찾은 벡터

를 이용하여 서브 캐리어별 영 공간으로의 파워 조절 매트릭스인

를 획득한다. 모든 사용자에 대한 통합 프리코더는

,

의 블록 대각화를 통해 설계될 수 있을 것이다. 최종 설계되는 통합 프리코더는 수학식 4에 정의되어 있다. In order to solve the optimization problem of Equation (13), an interior point method (interior point method) such as an infeasible path-following method

Looking for

To

Then, K vectors are searched. Vector found for all k

The subcarrier-to-subspace power adjustment matrix < RTI ID = 0.0 >

. An integrated precoder for all users

,

It can be designed through block diagonalization. The final designed integrated precoder is defined in Equation (4).

Once the SNR loss rate to be applied to the integrated precoder for all users and subcarriers is determined, the SNR loss rate of the precoder to be applied to each receiver is determined (step 204). The SNR loss rate to be applied to each receiver is the SNR loss rate multiplied by the effective power precoder of the precoder of each receiver in the integrated precoder and the sum of the SNR loss rates for each receiver is proportional to the determined SNR loss rate.

The SNR loss rate to be applied to each receiver is determined by the channel quality information of the transmitter and each receiver and the QoS required for each receiver. For example, if the channel quality information of a particular receiver is good and the required QoS is not high, a relatively high SNR loss rate is applied to the receiver. In addition, if the channel quality information of a particular receiver is not good and the required QoS is high, a relatively low SNR loss rate is applied to the receiver.

4 is a block diagram illustrating a structure of an SNR loss factor and precoder designing apparatus considering a target PAR according to an embodiment of the present invention.

4, the apparatus for designing an SNR loss rate and precoder according to an embodiment of the present invention includes an active power precoder design unit 400, a null space precoder design unit 410, an integrated precoder design unit 420, And an SNR loss rate determining unit 430.

Active power precoder design section (400) designs active power precoder associated with effective power to receivers of integrated pre-coder. As described above, the effective power precoder is determined based on a matrix representing the channel by SVD, and is designed as shown in Equation (5).

의 영 공간을 생성하는 기저벡터 들 중 c_j개의 기저벡터로 이루어진 일열 매트릭스인

를 이용하여 결정되며, 수학식 6과 같이 설계된다. The zero space pre-coder design section 410 designs a zero-space precoder which is a precoder associated with the beam into the null space of the integrated precoder. The zero-space precoder is a matrix of SVD channels

Of the base vectors generating the null space of c _j

And is designed as shown in Equation (6).

)과 영 공간 프리코더에 적용될 영 공간 파워 조절 매트릭스(T)를 결정하여 수학식 4와 같이 통합 프리코더를 설계한다. The integrated precoder design section 420 calculates the SNR loss rate (1-

) And a space power control matrix (T) to be applied to the null space precoder. The integrated precoder is designed as shown in Equation (4).

The receiver-specific SNR loss rate determination unit 430 determines the SNR loss rate of the precoder to be applied to each receiver based on the determined SNR loss rate of the integrated precoder. As described above, the SNR loss rate for each receiver can be determined using the channel quality information of the transmitter and each receiver and the required QoS.

As described above, the present invention has been described with reference to particular embodiments, such as specific elements, and specific embodiments and drawings. However, it should be understood that the present invention is not limited to the above- And various modifications and changes may be made thereto by those skilled in the art to which the present invention pertains. Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

Claims (14)

(A) designing a null-space precoder associated with a beam to be transmitted to the null space and a real power precoder associated with the beam that is effectively transmitted to the receivers using the estimated channel;
(B) designing an integrated precoder by determining an SNR loss factor to be applied to the active power precoder and a null space power adjustment matrix to be applied to the null space precoder; And
(C) determining an SNR loss rate to be applied to each receiver based on the SNR loss rate,
The SNR loss ratio and the null space power adjustment matrix are determined through the convex optimization so that the SNR loss rate is minimized while the target PAR is fixed,
Wherein the SNR loss rate to be applied to each receiver is determined using channel quality information with each receiver and a QoS required for each receiver, and the SNR loss rate determination and precoder designing method considering the target PAR.
The method according to claim 1,
The SNR loss rate (

) And the null space power control matrix are determined through the following convex optimization.

In the above equation, t is a vector constituting the space power modulation matrix T, d is a data stream, and K is the total number of subcarriers.

Denotes an inverse Fourier transform matrix. The method according to claim 1,
The step (c) is characterized by applying a relatively low SNR loss rate to a receiver having a good channel quality and a low required QoS, applying a relatively high SNR loss rate to a receiver having a poor channel quality and a high required QoS SNR loss rate and precoder design method considering target PAR.
3. The method of claim 2,
The active power precoder (

) Is a matrix obtained by SVD for the estimated channel

And

Wherein the SNR loss rate is calculated using Equation (1).

In the above equation, the subscript k is an index representing a subcarrier, and the subscript j is an index representing a receiver.
3. The method of claim 2,
The zero space pre-coder (

)

Of the base vectors generating the null space of c _j

And a matrix obtained by the SVD for the estimated channel

Wherein the SNR loss rate is calculated using Equation (1).

In the above equation, R denotes a reception filter of a receiver, H denotes an estimated channel, a superscript j denotes a receiver index, and a subscript k denotes a subcarrier index.
3. The method of claim 2,
Wherein the integrated precoder (F) to which the determined SNR loss rate and the null space power adjustment matrix T are applied is designed according to the following equation: SNR loss rate < RTI ID = 0.0 >

In the above equation,

Quot; means an active power precoder,

Means a zero-space precoder.
3. The method of claim 2,
The SNR loss rate (

) ≪ / RTI > and the null space power control matrix are determined through convex optimization taking into account the following additional conditions: < EMI ID = 16.1 >

In the above equation,

Denotes an inverse Fourier transform matrix,

The

Satisfy

Where M is the number of antennas of the transmitter,

Means the target PAR,

T denotes a transmission power of a symbol, t denotes a vector constituting a zero space power control matrix, b denotes a following equation,

And

Is a matrix obtained using the SVD for the estimated channel,

Is a transmission signal vector.
A real power precoder designing a real power precoder associated with a beam that is effectively transmitted to receivers using an estimated channel;
A zero space pre-coder designing a zero space pre-coder associated with the beam transmitted to the zero space;
An integrated precoder designing unit for designating an integrated precoder by determining an SNR loss rate to be applied to the active power precoder and a null space power adjustment matrix to be applied to the null space precoder; And
And a receiver-specific SNR loss rate determining unit for determining an SNR loss rate to be applied to each receiver based on the SNR loss rate,
The SNR loss ratio and the null space power adjustment matrix are determined through the convex optimization so that the SNR loss rate is minimized while the target PAR is fixed,
Wherein the SNR loss rate to be applied to each receiver is determined using channel quality information with each receiver and QoS required for each receiver.
9. The method of claim 8,
The SNR loss rate (

) And the null space power adjustment matrix are determined through the following convex optimization.

In the above equation, t is a vector constituting the space power modulation matrix T, d is a data stream, and K is the total number of subcarriers.

Denotes an inverse Fourier transform matrix.
9. The method of claim 8,
The receiver-specific SNR loss rate determination unit applies a relatively low SNR loss rate to a receiver having a good channel quality and a low required QoS and applies a relatively high SNR loss rate to a receiver having a bad channel quality and a high required QoS SNR loss rate decision and precoder design device considering target PAR.
10. The method of claim 9,
The active power precoder (

) Is a matrix obtained by SVD for the estimated channel

And

Wherein the SNR loss rate is determined according to the following equation.

In the above equation, the subscript k is an index representing a subcarrier, and the subscript j is an index representing a receiver.
10. The method of claim 9,
The zero space pre-coder (

)

Of the base vectors generating the null space of c _j

And a matrix obtained by the SVD for the estimated channel

Wherein the SNR loss rate is determined according to the following equation.

In the above equation, R denotes a reception filter of a receiver, H denotes an estimated channel, a superscript j denotes a receiver index, and a subscript k denotes a subcarrier index.
10. The method of claim 9,
Wherein the integrated precoder (F) to which the determined SNR loss rate and the null space power adjustment matrix T are applied is designed according to the following equation: < EMI ID = 1.0 >

In the above equation,

Quot; means an active power precoder,

Means a zero-space precoder.
10. The method of claim 9,
The SNR loss rate (

) ≪ / RTI > and the null space power control matrix are determined through the convex optimization taking into account the following additional conditions: < EMI ID = 16.1 >

In the above equation,

Denotes an inverse Fourier transform matrix,

The

Satisfy

Where M is the number of antennas of the transmitter,

Means the target PAR,

T denotes a transmission power of a symbol, t denotes a vector constituting a zero space power control matrix, b denotes a following equation,

And

Is a matrix obtained using the SVD for the estimated channel,

Is a transmission signal vector.

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