KR102206549B1 - Transmitting apparus and precoding method thereof - Google Patents

Abstract

According to one aspect of the present disclosure, a precoding method for a transmission apparatus including a 1-bit digital-to-analog converter (DAC) includes: calculating a first precoding vector by using a basic precoder; selecting at least one antenna to be switched off among a plurality of transmission antennas based on a preset threshold value; performing an algorithm for correcting an error vector of the first precoding vector on the first precoding vector to correct the error vector of the first precoding vector so as to obtain a second precoding vector; refining the second precoding vector to obtain a third precoding vector; and performing precoding by using the third precoding vector. Accordingly, an error floor problem in a large multi-antenna system is solved.

Description

Transmitting device and precoding method of the transmitting device {TRANSMITTING APPARUS AND PRECODING METHOD THEREOF}

The technical idea of the present disclosure relates to a transmission device and a precoding method of the transmission device.

The content described in this section merely provides background information on the present embodiment and does not constitute the prior art.

Recently, due to the generalization of information and communication services, the emergence of various multimedia services, and the emergence of high-quality services, the demand for wireless communication services is rapidly increasing. In order to actively cope with this, first of all, the capacity of the communication system must be increased.As a way to increase the communication capacity in a wireless communication environment, a method of finding a new available frequency band and a method of increasing the efficiency of limited resources can be considered. have. Among them, as a method of increasing the efficiency for limited resources, by attaching a plurality of antennas to the transceiver to additionally secure a spatial area for resource utilization, a diversity gain is obtained, or by transmitting data in parallel through each antenna. The so-called Multiple-Input-Multiple-Output (MIMO) antenna transmission and reception technology that increases transmission capacity is drawing attention.

These MIMO technologies are being actively developed while receiving greater attention in relation to the environment of a huge multi-antenna system in recent years. For example, as power consumption and system cost due to a large number of antennas are a problem due to the nature of a large multi-antenna system environment, a 1-bit resolution digital to analog converter (DAC) is used at a transmitter such as a base station as a solution. A method of performing MIMO transmission processing by using is proposed.

However, in the case of using a DAC of 1-bit resolution in a large multi-antenna system, when a general precoding scheme to increase data transmission reliability is applied, a signal to noise ratio (SNR) related problem occurs. Therefore, a solution to this is required.

A technical problem to be achieved by embodiments according to the technical idea of the present disclosure is to provide a transmission device for a large multi-antenna system and an efficient precoding method of the transmission device.

The technical problem to be achieved by the technical idea of the present disclosure is not limited to the problem mentioned above, and another problem that is not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present disclosure, a precoding method of a transmission device including a 1-bit digital to analog converter (DAC) includes calculating a first precoding vector using a basic precoder, Based on the step of selecting at least one or more antennas to be switched off from among a plurality of transmission antennas, an algorithm for correcting an error vector of the first precoding vector is performed with respect to the first precoding vector Obtaining a modified second precoding vector, obtaining a third precoding vector by refining the second precoding vector, and performing precoding using the third precoding vector It may include.

According to an exemplary embodiment, the selecting of the at least one or more antennas to be switched off may include an antenna to switch off a corresponding transmission antenna when the first precoding vector quantized by 1 bit is smaller than the preset threshold value. It may include the step of selecting.

According to an exemplary embodiment, the preset threshold may be determined by [Equation 4].

[Equation 4]

Here, θth is a threshold value, H † is a pseudo inverse of the channel matrix H , s is a transmission symbol vector, M is the number of transmission antennas, and ∥· ∥ ₁ is 1-norm.

According to an exemplary embodiment, in the obtaining of the modified second precoding vector, when H _j † s ≥ θth, an element of the corresponding second precoding vector is determined as H _j † s , and H _j † If s <θth, the step of determining a corresponding second precoding vector element as 0 may be included. Here, θth is a threshold value, H † is a pseudo inverse of the channel matrix H , and s is a transmission symbol vector.

According to an exemplary embodiment, obtaining the modified second precoding vector may include determining a first precoding vector as a second precoding vector when the error vector is 0.

According to an exemplary embodiment, the error vector may be determined by [Equation 8].

[Equation 8]

는 1비트 양자화기이다. Where e is an error vector, s is a transmission symbol vector, H is a channel matrix,

Is a 1-bit quantizer.

According to an exemplary embodiment, the obtaining of the third precoding vector includes determining a flip order to flip an element of the second precoding vector, and based on the flip order, the second precoding It may include flipping elements of the vector to obtain a third precoding vector in which the second precoding vector is flipped.

According to an exemplary embodiment, the obtaining of the third precoding vector in which the second precoding vector is flipped may include flipping an element of the second precoding vector, and the flipped 2A precoding vector and the flipped second precoding vector. Obtaining a 2B precoding vector, a matrix M determined by [Equation 10] for each of the second precoding vector, the flipped flipped 2A precoding vector, and the flipped flipped 2B precoding vector By multiplying by, a precoding vector having a result including an element having a minimum value may be determined as a third precoding vector.

[Equation 10]

Here, H is a channel matrix, and s is a transmission symbol vector.

을 만족하는 수열(

)이 있는 경우, 상기 플립 순서는

순서로 결정할 수 있다. According to an exemplary embodiment, the step of determining the flip order is in the vector v determined by [Equation 9]

A sequence that satisfies (

), the flip order is

You can decide in order.

[Equation 9]

Here, x is the second precoding vector.

According to an exemplary embodiment, the flipping of the elements of the second precoding vector to obtain the flipped 2A precoding vector and the flipped 2B precoding vector includes all elements of the second precoding vector. It may include performing a flip on the.

According to an exemplary embodiment, the basic precoder may include a ZF precoder.

A transmission apparatus according to another aspect of the present disclosure includes a transmission/reception unit, at least one processor, and a memory electrically connected to the processor, wherein the memory includes a first precoder using a basic precoder when the processor is executed. Calculate a precoding vector, select at least one antenna to be switched off from among a plurality of transmission antennas based on a preset threshold, and, for the first precoding vector, the first precoding Perform an algorithm for correcting an error vector of a vector to obtain a corrected second precoding vector, refine the second precoding vector to obtain a third precoding vector, and the third precoding vector Instructions for performing precoding can be stored using.

According to embodiments according to the technical idea of the present disclosure, there is an effect of providing an efficient precoding method capable of solving an error floor problem in a large multi-antenna system.

The effects that can be obtained by the embodiments according to the technical idea of the present disclosure are not limited to the above-mentioned effects, and other effects that are not mentioned are from the following description to those of ordinary skill in the art to which the present disclosure belongs. It can be clearly understood.

A brief description of each drawing is provided in order to more fully understand the drawings cited in the present disclosure.
1 is a diagram illustrating a 1-bit DAC downlink multi-antenna system according to an embodiment of the present disclosure.
FIG. 2 is a flowchart illustrating a precoding method of a transmission device including a 1-bit Digital to Analog Converter (DAC) according to an embodiment of the present disclosure.
3 is a diagram illustrating a performance comparison graph of a precoder according to antenna selection according to an embodiment of the present disclosure.
4 is a diagram illustrating an effect according to an antenna selection threshold according to an embodiment of the present disclosure.
5 is a diagram illustrating a configuration of a transmission device according to an embodiment of the present disclosure.
6 is a diagram showing a graph for comparing performance of a precoder.
7 is a diagram showing a performance comparison graph of a precoder.

The technical idea of the present disclosure is that various changes may be made and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the technical idea of the present disclosure to a specific embodiment, and it should be understood to include all changes, equivalents, and substitutes included in the scope of the technical idea of the present disclosure.

The technical idea of the present disclosure is that various changes may be made and various embodiments may be provided. Specific embodiments are illustrated in the drawings and will be described in detail through detailed description. However, this is not intended to limit the technical idea of the present disclosure to a specific embodiment, and it should be understood to include all changes, equivalents, and substitutes included in the scope of the technical idea of the present disclosure.

In describing the technical idea of the present disclosure, when it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the technical idea of the present disclosure, a detailed description thereof will be omitted. In addition, numbers (eg, first, second, etc.) used in the description of the present specification are merely identification symbols for distinguishing one component from another component.

In addition, in the present disclosure, when one component is referred to as "connected" or "connected" to another component, the one component may be directly connected or directly connected to the other component, but specifically It should be understood that as long as there is no opposing substrate, it may be connected or may be connected via another component in the middle.

In addition, terms such as "~ unit", "~ group", "~ character", and "~ module" described in the present disclosure mean a unit that processes at least one function or operation, which is a processor or microcomputer. Processor (Micro Processor), Application Processor (Application Processor), Micro Controller (Micro Controller), CPU (Central Processing Unit), GPU (Graphics Processing Unit), APU (Accelerate Processor Unit), DSP (Digital Signal Processor), ASIC ( Application Specific Integrated Circuit), FPGA (Field Programmable Gate Array), etc. may be implemented in hardware or software, or a combination of hardware and software.

In addition, it is intended to clarify that the division of the constituent parts in the present disclosure is merely divided by the main function that each constituent part is responsible for. That is, two or more constituent parts to be described below may be combined into one constituent part, or one constituent part may be divided into two or more according to more subdivided functions. In addition, each of the constituent units to be described below may additionally perform some or all of the functions of other constituent units in addition to its own main function, and some of the main functions of each constituent unit are different. It goes without saying that it may be performed exclusively by.

Hereinafter, embodiments according to the technical idea of the present disclosure will be described in detail in order.

1 is a diagram illustrating a 1-bit DAC downlink multi-antenna system according to various embodiments of the present disclosure.

는 다음과 같이 [수학식 1]에 의해 얻어질 수 있다. Referring to FIG. 1, an exemplary downlink multi-antenna system in which one base station having M transmit antennas and K users communicate with one antenna is illustrated. According to various embodiments of the present disclosure, each antenna of a base station is equipped with a 1-bit digital to analog converter (DAC). Here, a 1-bit quantized precoding vector

Can be obtained by [Equation 1] as follows.

는 전송 심볼 벡터

에 대한 프리코더 함수를 나타내며

는 각 엔트리의 실수 부와 허수 부 각각의 1 비트 양자화기를 나타낸다. 본 명세서 전체에 걸쳐, QPSK 성상도, 즉, 전송 심볼 벡터

∈ {1+j, 1-j, -1+j, -1-j}^k 임을 가정하여 설명한다. K 사용자들에 대한 이산 복소 값 기저대역 수신 신호 벡터

는 다음 [수학식 2]와 같다. here,

A transport symbol vector

Represents the precoder function for

Represents a 1-bit quantizer of each of the real and imaginary parts of each entry. Throughout this specification, QPSK constellation, that is, transmission symbol vector

The explanation assumes that ∈ {1+j, 1-j, -1+j, -1-j} ^k . Discrete complex-valued baseband received signal vector for K users

Is as the following [Equation 2].

는 기지국과 K 사용자 간의 채널 행렬을 나타낸다. 또한,

은 평균이 0이고 공분산이 σ² I 인 복소 가산 백색 가우스 잡음 벡터를 나타낸다. 이러한 시스템에 대하여 등가 실수 값 표현을 다음 [수학식 3]과 같이 나타낼 수 있다.here,

Represents a channel matrix between the base station and K users. Also,

Has mean 0 and covariance σ ² I Represents a complex additive white Gaussian noise vector. For this system, the equivalent real value expression can be expressed as the following [Equation 3].

,

,

, 그리고,

이다.here,

,

,

, And,

to be.

Re(·) and Im(·) represent real and imaginary parts for complex values, respectively. Due to the limitation of the QPSK arrangement due to the 1-bit DAC, we have xi ∈ {-1, 1}. In addition, when the base station considers the selection of an antenna in which some of the transmit antennas can be switched off, xi ∈ {-1, 0, 1}.

FIG. 2 is a flowchart illustrating a precoding method of a transmission device including a 1-bit Digital to Analog Converter (DAC) according to an embodiment of the present disclosure.

In step 210, the transmitting device calculates a first precoding vector using a basic precoder. In one embodiment, the basic precoder may include a ZF precoder.

In step 220, the transmitting device selects at least one or more antennas to be switched off from among the plurality of transmitting antennas based on a preset threshold. In an embodiment, when the first precoding vector quantized by 1-bit is smaller than the preset threshold, the transmitting device may select a corresponding transmitting antenna as an antenna to be switched off.

Existing precoding methods such as ZF, Sum-Max, and Max-Min have a serious error floor problem in the medium-high SNR region. This problem can be confirmed by looking at the precoder performance comparison graphs of FIGS. 6 and 7.

6 is an 8 X 4 1-bit DAC downlink multi-antenna system, M = 8, K = 4, ZF, Sum-Max, Max-Min, Symbol Scaling under QPSK modulation conditions, ASI-ZF free according to an embodiment This is a graph comparing the performance of coders. Referring to FIG. 3, it can be seen that an error floor occurs in ZF, Sum-Max, Max-Min, and Symbol Scaling precoders excluding the ASI-ZF precoder according to an embodiment.

7 is a 64 X 16 1-bit DAC downlink multi-antenna system, M = 64, K = 16, ZF, Sum-Max, Max-Min, Symbol Scaling under QPSK modulation conditions, ASI-ZF free according to an embodiment. This is a graph comparing the performance of coders. Referring to FIG. 4, it can be seen that an error floor occurs in ZF, Sum-Max, Max-Min, and Symbol Scaling precoders excluding the ASI-ZF precoder according to an embodiment.

According to an embodiment, this error floor problem can be solved by introducing antenna selection (ie, switching off some transmit antennas). The precoded vector to which antenna selection is applied can be determined by taking the following optimization problem solution.

Here, x _j = 0 means that the transmit antenna corresponding to the element is turned off (ie, not used). If antenna selection is used, the number of candidates that can be used as precoding vectors can be increased, thereby improving performance. This optimization problem aims to maximize the minimum value of the magnitude of each received signal when all received signals are located in the correct quantization region.

3 is a diagram illustrating a performance comparison graph of a precoder according to antenna selection according to an embodiment of the present disclosure.

In Fig. 3, it can be confirmed that the performance is improved by actually mitigating the error floor problem by using antenna selection through the simulation result. 3 is a graph comparing exhaustive search performance under M = 8, K = 4, and QPSK modulation conditions in an 8 X 4 1-bit DAC downlink multi-antenna system. Referring to FIG. 3, it can be seen that exhaustive search performance is improved by using antenna selection according to an embodiment.

In addition, it can be seen that performance improvement is possible when antenna selection is used through Examples 1 and 2 below.

Example 1

Assume a downlink MIMO system with M = 4 and K = 3, and assume a transmission symbol vector s as follows.

In addition, it is assumed that the channel matrix H is as follows.

In this case, an appropriate 1-bit precoding vector can be found as follows using an exhaustive search technique to which antenna selection is not applied.

An appropriate 1-bit precoding vector obtained by using an appropriate exhaustive search technique to which antenna selection is applied is as follows.

Comparing the minimum values of the signal elements received by the user in the two cases, min( Hx ₁ ) <min( Hx ₂ ). In this case, applying antenna selection can transmit a signal that is stronger against noise, and thus performance It can be seen that this can be improved.

Example 2.

Assume a downlink MIMO system with M = 4 and K = 3, and assume a transmission symbol vector s as follows.

In addition, it is assumed that the channel matrix H is as follows.

In this case, an appropriate 1-bit precoding vector cannot be found using an exhaustive search technique to which antenna selection is not applied. That is, when antenna selection is not applied, errors are detected in all available 1-bit precoding vectors.

However, it is shown that the error floor occurring in the medium-high SNR region can be mitigated by using the antenna selection using the appropriate 1-bit precoding vector obtained through the appropriate exhaustive search technique applying antenna selection as follows.

In one embodiment, the preset threshold may be determined by [Equation 5].

Here, θth is a threshold value, H † is a pseudo inverse of the channel matrix H , s is a transmission symbol vector, M is the number of transmission antennas, and ∥ · ∥ ₁ is 1-norm.

More specifically, a threshold value for turning off some antennas is required to apply antenna selection. In an embodiment, an appropriate threshold value may be determined using Monte-Carlo simulation, but the present invention is not limited thereto, and the threshold value may be determined in various ways. When a 1-bit signal is transmitted, the size of the received signal is about 0.8 times the size of the received signal when a signal with unlimited resolution is transmitted. If an appropriate threshold is used, the change in the size of the received signal can be minimized when a 1-bit signal is transmitted. Referring to FIG. 4, the effect of antenna selection according to the threshold value can be checked.

In step 230, the transmitting device obtains a modified second precoding vector by performing an algorithm for correcting an error vector of the first precoding vector with respect to the first precoding vector.

In an embodiment, when obtaining the modified second precoding vector, if H _j † s ≥ θth, the corresponding element of the second precoding vector is determined as H _j † s , and H _j † s <θth In this case, the corresponding second precoding vector element may be determined as 0. Here, θth is a threshold value, H † is a pseudo inverse of the channel matrix H , and s is a transmission symbol vector. In addition, when the error vector is 0, the first precoding vector may be determined as the second precoding vector.

Infinite resolution ZF precoder can be used as follows.

Each element of the infinite resolution ZF precoding vector x to which the threshold value described above is applied can be expressed as follows.

Here, x _j represents the j-th element of the precoding vector x, H † _j represents the j-th row entries of the channel matrix H pseudo inverse matrix H †. In addition, an error vector e that occurs when a precoded vector is transmitted through a noise-free channel can be defined as follows.

는 1비트 양자화기이다. 이때, 오류 벡터 e가 영벡터가 아니라면 프리코딩 된 프리코딩 벡터 x는 높은 SNR 영역에서 오류 플로어가 발생한다. 따라서 위의 오류 벡터 e를 수정하기 위해 [알고리즘 1]을 수행해야 한다. 일 실시예에 따른 [알고리즘 1]은 다음과 같다. Where e is an error vector, s is a transmission symbol vector, H is a channel matrix,

Is a 1-bit quantizer. At this time, if the error vector e is not a zero vector, the precoded precoding vector x generates an error floor in a high SNR region. Therefore, [Algorithm 1] must be performed to correct the error vector e above. [Algorithm 1] according to an embodiment is as follows.

[Algorithm 1]

In addition, steps 210 to 230 may be referred to as a basic precoding process. This basic precoding process can be expressed as [Algorithm 2].

[Algorithm 2]

In step 240, the transmission device refines the second precoding vector to obtain a third precoding vector. In one embodiment, when obtaining a third precoding vector, a flip order is determined to flip elements of the second precoding vector, and based on the determined flip order, elements of the second precoding vector are flipped to A third precoding vector in which the precoding vector is flipped may be obtained.

을 만족하는 수열(

)이 있는 경우,

순서로 결정할 수 있다. In one embodiment, the flip order is in the vector v determined by [Equation 9]

A sequence that satisfies (

),

You can decide in order.

Here, x is the second precoding vector.

In more detail, the order of flips may be determined by the value of the matrix M calculated by the channel matrix H and the transmission symbol vector s . Matrix M can be calculated as follows.

을 만족하는 수열(

)이 있는 경우, 상기 플립 순서는

순서로 결정할 수 있다. M _i,j is i∈{1,… for matrix M , 2K}th row item and j∈{1,… , 2M}-th column item. And H _i,j is i∈{1,… for the channel matrix H , 2K}th row item and j∈{1,… , 2M}-th column item. Also, the symbol s _i is i∈{1,… for the transmission symbol vector s . , 2K}th item. Each element of the vector v home, and vector v may be determined by the formula 10] described above. As described above,

A sequence that satisfies (

), the flip order is

You can decide in order.

In one embodiment, when obtaining the third precoding vector in which the second precoding vector is flipped, the elements of the second precoding vector are flipped to obtain the flipped 2A precoding vector and the flipped 2B precoding vector. And multiplying each of the second precoding vector, the flipped flipped 2A precoding vector, and the flipped flipped 2B precoding vector by a matrix M determined by [Equation 10] to include an element having a minimum value. The precoding vector having the result may be determined as the third precoding vector. In addition, when the elements of the second precoding vector are flipped to obtain the flipped 2A precoding vector and the flipped 2B precoding vector, flip can be performed on all elements of the second precoding vector.

번째 요소를 플립한다. 안테나 선택에 의해서 2 가지의 플립된 프리코딩 벡터를 얻을 수 있다. 각각 플립된 프리코딩 벡터를 x', x'' 라 한다. 만약,

= 1 인 경우, 제2 프리코딩 벡터 x 와 플립된 프리코딩 벡터 x', x'' 의 요소는 각각 다음과 같이 나타낼 수 있다. More specifically, first, the second precoding vector x

Flip the second element. Two flipped precoding vectors can be obtained by antenna selection. Each flipped precoding vector is referred to as x'and x'' . if,

In the case of = 1, elements of the second precoding vector x and the flipped precoding vectors x'and x'' can be expressed as follows.

Thereafter, if Mx = β, Mx '= γ, Mx '' = δ , the minimum values of the elements min( β ), min( γ ), and min( δ ) are compared for the three vectors β , γ , and δ . If the value of min( γ ) is the maximum value, then the precoding vector x is replaced by the flipped precoding vector x' , and if the value of min( δ ) is the maximum value, the precoding vector x is the flipped precoding vector x'' , and if the value of min( β ) is the maximum, the precoding vector x is maintained.

번째 요소에 대해서도 반복하고, 나아가, 제2 프리코딩 벡터 x의 모든 구성요소, 즉,

번째 요소를 모두 플립 할 때까지 반복한다.This process of the second precoding vector x

Repeat for the second element, furthermore, all components of the second precoding vector x , that is,

Repeat until all the first elements are flipped.

Step 240 may be referred to as a refine process. This refinement process can be expressed as [Algorithm 3].

[Algorithm 3]

In step 250, the transmitting device performs precoding using the third precoding vector.

6 is a diagram showing a graph for comparing performance of a precoder.

6 is an 8 X 4 1-bit DAC downlink multi-antenna system, M = 8, K = 4, ZF, Sum-Max, Max-Min, Symbol Scaling under QPSK modulation conditions, ASI-ZF free according to an embodiment This is a graph comparing the performance of coders.

For each element of the channel matrix, a Rayleigh fading channel derived from an iid cyclically symmetric complex Gaussian random variable with zero mean and unit variance is assumed. In addition, it is assumed that the channel matrix H is fully known to the base station.

Referring to FIG. 6, it was found that the precoding method according to an embodiment has better performance than the ZF precoding algorithm and the Symbol Scaling algorithm in all SNR regions. In addition, it can be confirmed that an error floor occurs for all simulated methods in the mid-high SNR region. The computational complexity ψ of each simulated precoding algorithm can be summarized as follows.

It can be seen that the precoding method according to an embodiment having such a complexity has a usable level of complexity. That is, the precoding method according to an embodiment can be applied to an actual system unlike nonlinear precoding techniques such as SDR and sphere decoding having high complexity.

7 is a diagram showing a performance comparison graph of a precoder.

7 is a 64 X 16 1-bit DAC downlink multi-antenna system, M = 64, K = 16, ZF, Sum-Max, Max-Min, Symbol Scaling under QPSK modulation conditions, ASI-ZF free according to an embodiment. This is a graph comparing the performance of coders.

7 is a comparison of a precoding method according to an embodiment with a ZF, Symbol Scaling precoding technique in a large-scale MIMO system. Unlike in a small MIMO system, the precoding method according to an embodiment does not generate an error floor. However, in the symbol scaling and ZF precoding schemes, an error floor still occurs in the intermediate SNR region. In addition, since the precoding method according to an embodiment, that is, the ASI-ZF method, consumes less total antenna power than the ZF method, there is a power gain under the total antenna power constraint.

Referring to the computational complexity Ψ of the algorithm, it can be seen that as the system size increases, the interval between the computational complexity of the precoding method according to an embodiment and the computational complexity of the Symbol Scaling technique decreases.

As a result, according to an embodiment, it is possible to have superior performance to the ZF technique and the conventionally proposed Symbol Scaling technique in the entire SNR domain. Unlike nonlinear precoding methods such as SDR precoder and sphere decoding that cannot be used in large-scale MIMO systems, the precoding method according to an embodiment has a complexity that can be used in small and large-scale MIMO systems.

5 is a diagram illustrating a configuration of a transmission device according to an embodiment of the present disclosure.

Referring to FIG. 5, the transmission device 500 may include a transceiver 510, a memory 520, and a processor 530. However, the components of the transmission device 500 are not limited to the above-described example. For example, the transmission device 500 may include more or fewer components than the above-described components.

In one embodiment, the transmission/reception unit 510 may transmit and receive signals. To this end, the transceiver 510 may include an RF transmitter and an RF receiver. The transceiver 510 may receive a signal through a wireless channel, output it to the processor 530, and transmit a signal output from the processor 530 through a wireless channel.

In one embodiment, the memory 520 may store programs and data necessary for the operation of the transmission device 500. In addition, the memory 520 may store control information or data included in signals transmitted and received by the terminal. The memory 520 may be formed of a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM, a DVD, or a combination of storage media. The memory 520 is electrically connected to the processor 530.

In one embodiment, the processor 530 may control a series of processes in which the transmission device 500 may operate according to the above-described embodiments of the present disclosure. In one embodiment, the processor 530 may be configured with one or more processors.

In one embodiment, the processor 530 calculates a first precoding vector using a basic precoder, and based on a preset threshold, at least one or more of the plurality of transmit antennas to be switched off. An antenna is selected, and an algorithm for correcting an error vector of the first precoding vector is performed on the first precoding vector to obtain a modified second precoding vector, and the second precoding vector is refined. A third precoding vector may be obtained by (refine), and instructions for performing precoding using the third precoding vector may be executed.

Meanwhile, the embodiments of the present disclosure disclosed in the present specification and drawings are merely provided with specific examples to easily describe the technical content of the present disclosure and to aid understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. That is, that other modified examples based on the technical idea of the present disclosure may be implemented is obvious to those of ordinary skill in the technical field to which the present disclosure belongs. In addition, each of the above-described embodiments may be combined and operated as necessary.

500: transmitting device
510: transceiver
520: memory
530: processor

Claims (12)

In the precoding method of a transmission device including a 1-bit DAC (Digital to Analog Converter),
Calculating a first precoding vector based on the pseudo-inverse matrix of the channel matrix and the transmission symbol vector;
Obtaining a corrected second precoding vector by performing an algorithm for correcting an error vector of the first precoding vector on the first precoding vector;
Refining the second precoding vector to obtain a third precoding vector; And
Comprising the step of performing precoding using the third precoding vector,
The error vector is determined by [Equation 8]
[Equation 8]

Where e is an error vector, s is a transmission symbol vector, H is a channel matrix,

Is a 1-bit quantizer,
The step of obtaining the modified second precoding vector,
Determining an element of a corresponding second precoding vector as an element of the first precoding vector when an element of the first precoding vector is equal to or greater than a preset threshold; And
If an element of the first precoding vector is less than the threshold, determining an element of a corresponding second precoding vector as 0,
The step of obtaining the third precoding vector,
Determining a flip order to flip elements of the second precoding vector; And
Based on the flip order, flipping elements of the second precoding vector to obtain a third precoding vector in which the second precoding vector is flipped.
delete The method of claim 1,
The preset threshold is determined by [Equation 4].
[Equation 4]

Here, θth is the threshold value, H † is the pseudo inverse of the channel matrix H , s is the transmit symbol vector, M is the number of transmit antennas, and ∥· ∥ ₁ is 1-norm.
delete The method of claim 1,
The step of obtaining the modified second precoding vector,
If the error vector is 0, determining a first precoding vector as a second precoding vector.
delete delete The method of claim 1,
Obtaining a third precoding vector in which the second precoding vector is flipped,
Flipping elements of the second precoding vector to obtain a flipped 2A precoding vector and a flipped 2B precoding vector;
The second precoding vector, the flipped 2A precoding vector, and the flipped 2B precoding vector are each multiplied by a matrix M determined by [Equation 10] to obtain a result including an element having a minimum value. Determining the precoding vector as the third precoding vector.
[Equation 10]

Here, H is a channel matrix, and s is a transmission symbol vector.
The method of claim 8,
The step of determining the flip order,
In the vector v determined by [Equation 9]

A sequence that satisfies (

), the flip order is

Decided in order, how.
[Equation 9]

Here, x is the second precoding vector.
The method of claim 8,
Flipping the elements of the second precoding vector to obtain a flipped 2A precoding vector and a flipped 2B precoding vector,
And performing a flip on all elements of the second precoding vector.
The method of claim 1,
The method, wherein calculating the first precoding vector is performed using a ZF precoder.
A transceiver;
At least one processor; And
Comprising a memory electrically connected to the processor,
The memory, when the processor is executed,
Based on the pseudo-inverse matrix of the channel matrix and the transmission symbol vector, calculate a first precoding vector,
Obtaining a modified second precoding vector from the first precoding vector, based on the comparison result between the first precoding vector and a preset threshold,
Determining a flip order for flipping the elements of the second precoding vector, and obtaining a third precoding vector by flipping the elements of the second precoding vector based on the determined flip order,
A transmission device that stores instructions for performing precoding using the third precoding vector.

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