KR20230040568A - System and Method for wireless power transfer having receiving power based beam scanning algorithm to achieve optimized transfer efficiency - Google Patents

Abstract

Disclosed is a system for wireless power transmission, which may realize a received power-based beam scanning algorithm for optimizing transmission efficiency by utilizing a reconfigurable intelligent surface (RIS). To this end, the system for wireless power transmission is characterized by comprising: a transmission end having a first antenna composed of a plurality of first reconfigurable intelligent surface (RIS) unit cells; a RIS array block in which a rectangular-shaped RIS tile, composed of a plurality of second RIS unit cells, is partially aligned in plural; and a receiving end having a second antenna composed of a plurality of third RIS unit cells.

Description

System and method for wireless power transfer having receiving power based beam scanning algorithm to achieve optimized transfer efficiency}

The present invention relates to wireless power transmission technology, and more particularly, to a wireless power transmission system and method for implementing a received power-based beam scanning algorithm for optimizing transmission efficiency by utilizing a reconfigurable intelligent surface (RIS). will be.

There have been many proposals to implement this for wireless power transmission technology. A wireless transmission system is proposed by implementing a double 3D metastructure.

In this case, although overall miniaturization and high efficiency of the wireless power transmission system have been achieved, it is a technology focused on short-distance wireless power transmission and beam steering and focusing for long-distance wireless power transmission cannot be performed. That is, there is a problem in that the transmitter and the receiver must be arranged side by side to ensure high power transfer efficiency.

In addition, although a method of adopting a surface reflection array plane has been proposed to focus electromagnetic waves, there is a disadvantage in that utilization for beam steering and wireless power transmission is not implemented.

In addition, a wireless power transmission method and apparatus for a vehicle using a metal material as a focusing lens for concentrating electromagnetic radiation from a transmitter to a receiver has been proposed. In this case, only information about short-distance wireless power transmission using electromagnetic induction is disclosed in the system.

In addition, another RF (Radio Frequency) lens array method has been proposed. In this case, the RF lens array includes a plurality of copiers used for wireless power transmission. In addition, only features are disclosed that are modulated to concentrate radiated power in a narrow space and to supply power to an electronic device disposed in the space.

In addition, a technique capable of increasing the efficiency of wireless power transmission using status/information transmitted from a receiver has been proposed. In this case, it is limited to short-distance power transmission, and there is a problem in that a reconfigurable intelligent surface (RIS) does not mention a plane.

In addition, a beam steering technology using RIS has been proposed. In this case, after assuming that there is a receiving end in a Fresnel region through paraxial ray beam formation using RIS, beam steering to that position is only presented.

In addition, a technique for beam steering based on a scattering matrix has been proposed. In this case, the beam steering based on the scattering matrix of the system is only presented under an environment where the impedance value of each unit cell of the RIS can be freely adjusted. That is, only a technology for beam steering is disclosed.

1. Korea Patent Publication No. 10-2019-0109809

The present invention has been proposed to solve the problems caused by the above background art, and a wireless power transmission system and method for implementing a received power-based beam scanning algorithm for optimizing transmission efficiency by utilizing a reconfigurable intelligent surface (RIS). Its purpose is to provide

In addition, another object of the present invention is to provide a wireless power transmission system and method having an algorithm capable of implementing adaptive beam focusing according to the location of a receiving end only with a received power level.

In addition, another object of the present invention is to provide a wireless power transmission system and method capable of greatly reducing complexity without requiring additional hardware installation in a receiving end.

In order to achieve the above object, the present invention provides a wireless power transmission system that implements a received power-based beam scanning algorithm for optimizing transmission efficiency by utilizing a reconfigurable intelligent surface (RIS).

The wireless power transmission system,

a transmitter having a first antenna composed of a plurality of first RIS (Reconfigurable Intelligent Surface) unit cells;

a RIS array block configured by partially arranging a plurality of rectangular RIS tiles composed of a plurality of second RIS unit cells;

It is characterized by including; a receiving end having a second antenna consisting of a plurality of third RIS unit cells.

At this time, the transmitting end defines each unit cell adjustment value for beam forming and steering through channel information analysis between the transmitting end, the RIS array block, and the receiving end, and based on the unit cell adjustment value, for each subarray It is characterized by performing beam scanning.

In addition, the beam forming is characterized in that the detection of the received power level at the receiving end is used.

In addition, the first antenna and the second antenna are characterized in that a rectangular planar array antenna in which a plurality of single antenna elements are arranged in the x-axis and the y-axis to have a coordinate system.

및

(여기서,

는 각각 x 및 y 방향에서 인접한 단일 안테나 구성요소 간격이고, Tx는 송신단을 의미하고, Rx는 수신단을 의미하고, M,N,m,n은 양의 자연수이고,

는 수학적 모델로써 J개를 가지는 어떠한 모델에서 j번째에 있는 것을 가리키며, T는 전치 행렬을 의미하고,

,

는 가로로 M개의 단일 안테나 구성요소를 가지는 송신용 평면 안테나에서 가로로 m번 째 단일 안테나 구성요소,

는 세로로 N개의 단일 안테나 구성요소를 가질 때, 세로로 n번 째에 있는 단일 안테나 구성요소를 가리키며,

는 가로로 M개의 단일 안테나 구성요소를 가지는 수신용 평면 안테나에서 가로로 m번 째 단일 안테나 구성요소,

는 세로로 N개의 단일 안테나 구성요소를 가질 때, 세로로 n번 째에 있는 단일 안테나 구성요소를 가리킨다)으로 정의되는 것을 특징으로 한다.In addition, the positions (μ) of the first RIS unit cell (m,n) index of the transmitter and the third RIS unit cell (m,n) index of the receiver are respectively Equation

and

(here,

are adjacent single antenna element spacings in the x and y directions, respectively, Tx denotes the transmitting end, Rx denotes the receiving end, M, N, m, n are positive natural numbers,

Indicates the jth in any model with J as a mathematical model, T means a transposition matrix,

,

is the m-th single antenna element horizontally in a transmission planar antenna having M single antenna elements horizontally ,

When has N single antenna elements vertically, refers to the single antenna element in the nth position vertically,

is the m-th single antenna element horizontally in a reception planar antenna having M single antenna elements horizontally ,

When having N number of single antenna elements in the vertical direction, it refers to the single antenna element in the nth position in the vertical direction).

의 상기 제 2 RIS 단위셀의 부분배열을 가지며, 상기 제 2 RIS 단위셀 (m,n) 인덱스의 위치(μ)는 수학식

(여기서,

,

및

은 각각 x 및 y 방향에서 정의된 RIS 단위 셀 간격이고,

는 RIS 타일 K가 가로로 M개의 단위셀을 가질 때 가로로부터 m번 째 있는 단위셀이고,

는 RIS 타일 K가 세로로 N개의 단위셀을 가질 때 세로로부터 n번 째 있는 단위셀이다)으로 정의되는 것을 특징으로 한다.In addition, the tile k indexed by the RIS tile is

has a partial arrangement of the second RIS unit cell of, and the position (μ) of the second RIS unit cell (m, n) index is Equation

(here,

,

and

are the RIS unit cell spacing defined in the x and y directions, respectively,

is the mth unit cell from the horizontal when the RIS tile K has M unit cells horizontally,

is the n-th unit cell from the vertical when the RIS tile K has N unit cells vertically).

) 및 상기 RIS 타일의 원점과 상기 수신단 사이의 거리(

)에 비해 작은 것을 특징으로 한다.In addition, the size of the RIS tile is the distance between the origin of the transmitter and the RIS tile (

) and the distance between the origin of the RIS tile and the receiving end (

) is smaller than that of

(여기서,

및

는 각각 상기 송신단에서 상기 RIS 타일까지의 고도각 및 방위각이고,

및

은 각각 상기 RIS 타일에서 상기 송신단까지의 고도각 및 방위각이고, T는 전치이다)으로 정의되는 것을 특징으로 한다.In addition, the uv coordinate (S) of the direction from the transmitter to the RIS tile is

(here,

and

are elevation angles and azimuth angles from the transmitter to the RIS tile, respectively;

and

is an elevation angle and an azimuth angle from the RIS tile to the transmitter, respectively, and T is a transposition).

(여기서,

및

는 각각 IS 타일에서 반사된 전자기파의 고도각 및 방위각이고, T는 전치이다)으로 정의되는 것을 특징으로 한다.In addition, a control parameter for control is set for the RIS tile, the control parameter is composed of a direction control parameter (c _k ) and a phase control parameter (w _k ), and the direction control parameter (c k ) _k ) is the equation

(here,

and

are the elevation and azimuth angles of the electromagnetic wave reflected from the IS tile, respectively, and T is the displacement).

)는 수학식

으로 정의되는 것을 특징으로 한다.In addition, when the continuous phase shift is performed using the direction control parameter (c _k ) and the phase control parameter (w _k ), the reflection coefficient of the index of the second unit cell 121 (m, n) of the RIS tile (

) is the equation

It is characterized by being defined as

(여기서,

및

는 각각 송신된 전자기파의 고도각 및 방위각이다)으로 정의되는 것을 특징으로 한다.In addition, the direction control parameter (q) of the transmitter is

(here,

and

is an elevation angle and an azimuth angle of the transmitted electromagnetic wave, respectively).

)는 수학식

(여기서, p는 송신되는 전력값이고,

이다)으로 정의되는 것을 특징으로 한다.In addition, when the direction control parameter (q), the electromagnetic wave transmitted from the single antenna element (m, n) of the transmitting end (

) is the equation

(Where, p is the transmitted power value,

It is characterized by being defined as).

(여기서,

,

그리고

는 상기 송신단과 상기 RIS 타일 사이의 공간적 관계(spatial relationship)이고, Tx는 송신단을 의미하고, Rx는 수신단을 의미하고, M,N,m,n,i,j,a,b)은 양의 자연수이다)로 정의되는 것을 특징으로 한다.In addition, the distance (d) between the single antenna element (i, j) of the transmitter and the second unit cell 121 (m, n) of the RIS tile is expressed by Equation

(here,

,

and

Is the spatial relationship between the transmitter and the RIS tile, Tx means the transmitter, Rx means the receiver, M, N, m, n, i, j, a, b) is positive It is characterized by being defined as a natural number).

(여기서, h는 단일 안테나 구성요소(i,j)에서 상기 RIS 타일의 제 2 단위셀(m,n)로의 채널 이득이고, x_i,j(q)는 방향 제어 매개 변수가 q일 때 송신단의 단일 안테나 구성요소(i,j)에서 송신된 전자기파를 의미하고, λ는 파장의 길이이고,

및

는 상기 RIS 타일(123)에 대한 상기 송신단 및 상기 수신단의의 안테나 이득을 나타내고,

및

는 상기 송신단 및 상기 수신단에 대한 상기 RIS 타일의 단위셀 이득이고, (a,b)는 수신단(130)의 단일 안테나 구성요소를 나타내고, c_k는 방향 제어 매개 변수이고, w_k는 위상 제어 매개 변수이고,

,

그리고

는 상기 수신단과 상기 RIS 타일 사이의 공간적 관계(spatial relationship)이고,

,

그리고

상기 송신단과 상기 RIS 타일 사이의 공간적 관계이다)을 통해 이루어지는 것을 특징으로 한다.In addition, the analysis of the beam forming and steering is performed by Equation

(Where, h is the channel gain from a single antenna element (i, j) to the second unit cell (m, n) of the RIS tile, and x _{i, j} (q) is the transmitting end when the direction control parameter is q Means an electromagnetic wave transmitted from a single antenna component (i, j) of , λ is the length of the wavelength,

and

Represents the antenna gain of the transmitting end and the receiving end for the RIS tile 123,

and

Is the unit cell gain of the RIS tile for the transmitting end and the receiving end, (a, b) represents a single antenna element of the receiving end 130, c _k is a direction control parameter, and w _k is a phase control parameter is a variable,

,

and

Is a spatial relationship between the receiving end and the RIS tile,

,

and

It is a spatial relationship between the transmitter and the RIS tile).

로 설정하는 것을 특징으로 한다.In addition, in the case of the steering, the RIS tile sets the direction control parameter (c _k )

It is characterized by setting to .

In addition, the RIS tile is characterized in that the phases of beams at the receiving end are aligned so that all waves are combined at the receiving end through adjustment of the phase control parameter (w _k ).

(여기서,

,

이고, u,v방향의 스캐닝 단계별 크기는 각각

이다)을 통해 이루어지는 것을 특징으로 한다.In addition, the direction control (c _k ) of the RIS tile at the point scanned according to the beam scanning is expressed by Equation

(here,

,

, and the size of each scanning step in the u and v directions is

is) characterized in that it is made through.

In addition, the receiving end records the received power according to the on / off pattern of the second RIS unit cell and a beam index corresponding to the received power and a partial array currently being scanned, information of the received power and the beam index characterized in that it transmits to the transmitting end.

On the other hand, in another embodiment of the present invention, a transmitter having a first antenna made up of a plurality of first reconfigurable intelligent surface (RIS) unit cells, a plurality of rectangular RIS tiles made up of a plurality of second RIS unit cells. A wireless power transmission method of a wireless power transmission system comprising: a receiving end having a second antenna composed of arranged and configured RIS array blocks and a plurality of third RIS unit cells, wherein (a) the transmitting end comprises the transmitting end, the RIS Defining each unit cell adjustment value for beam formation and steering through channel information analysis between an array block and the receiving end; and (b) the transmitting end performing beam scanning for each sub-array based on the unit cell adjustment value. It provides a wireless power transmission method comprising the; step of performing.

According to the present invention, since optimal transmission efficiency can be achieved only with the received power information, additional hardware is not required for the receiver, so it can be easily applied to low-power Internet of Things (IoT) devices and wearable devices. This can lower manufacturing cost and greatly reduce energy consumption, which has great advantages in terms of commercialization.

In addition, as another effect of the present invention, it is not limited to the beam steering method using RIS (Reconfigurable Intelligent Surface), and it is possible to perform adaptive beam focusing that effectively transmits power no matter where the receiver is located. It can be said that it is very suitable.

In addition, another effect of the present invention is that it can be applied regardless of the number of unit cells of RIS, and it can be used without additional modification even for RIS composed of thousands or tens of thousands of unit cells in 5G/6G to be commercialized in the future. can be heard

1 is a conceptual diagram of a wireless power transfer system using a reconfigurable intelligent surface (RIS) according to an embodiment of the present invention.
FIG. 2 is a perspective view and an equivalent circuit of the RIS unit cell shown in FIG. 1 .
FIG. 3 is a configuration block diagram of a transmitter shown in FIG. 1;
FIG. 4 is a detailed block diagram of a control unit shown in FIG. 3 .
5 is a flowchart illustrating a process of wireless power transmission using RIS according to an embodiment of the present invention.
6 is a graph showing received power for each beam index according to an embodiment of the present invention.
7 is a phase control graph of a transmitter according to an embodiment of the present invention.
8 is a graph showing a RIS optimal pattern according to an embodiment of the present invention.
9 is a graph showing locations of a transmitting end, a receiving end, and RIS according to an embodiment of the present invention.
10 is a graph showing the relationship of distance versus power transmission efficiency according to an embodiment of the present invention.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents, or substitutes included in the spirit and scope of the present invention.

In describing each figure, like reference numbers are used for like elements.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. These terms are only used for the purpose of distinguishing one component from another.

For example, a first element may be termed a second element, and similarly, a second element may be termed a first element, without departing from the scope of the present invention. The term "and/or" includes any combination of a plurality of related listed items or any of a plurality of related listed items.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and unless explicitly defined in this application, it should not be interpreted in an ideal or excessively formal meaning. Should not be.

Hereinafter, a wireless power transmission system and method having a received power-based beam scanning algorithm for achieving transmission efficiency according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

An embodiment of the present invention discloses a simple and efficient beam scanning algorithm suitable for RIS that can be controlled only with passive elements.

1 is a conceptual diagram of a wireless power transmission system 100 using a reconfigurable intelligent surface (RIS) according to an embodiment of the present invention. Referring to FIG. 1 , a wireless power transfer system 100 may include a transmitter 110, a RIS array block 120, a receiver 130, and the like.

The transmitter 110 may include an antenna on which the RIS unit cell 111 is arranged.

In the RIS array block 120 , rectangular tiles 123 formed of RIS unit cells 121 are arranged on a substrate 122 .

The receiving terminal 130 may include an antenna made of RIS unit cells 131.

The transmitter 110 defines each unit cell adjustment value for beam forming and steering through channel information analysis between the transmitter 110, the RIS array block 120, and the receiver 130, and each unit Beam scanning is performed for each subarray based on the cell adjustment value.

In the case of the RIS array block 120, considering the number of unit cells of the RIS (Reconfigurable Intelligent Surface), that is, near field & far field characteristics that vary depending on the physical size, the RIS array block is divided into several subarrays Because of the divided approach, the problem of channel characteristics being different in the near field can also be overcome.

In general, IoT (Internet of Things) and wearable devices, which are the main targets of indoor space long-distance wireless free charging, have limited hardware and computational power, so algorithms widely used in existing communication systems cannot be applied.

Therefore, in consideration of the characteristics of the IoT device, the beam focusing method of the algorithm according to an embodiment of the present invention is proposed to achieve optimal power transmission efficiency only by detecting the received power level in the receiving terminal 130.

In the remote wireless power transmission system 100 using RIS, the transmitter 110 (or power beacon) emits electromagnetic waves and transfers power to the receiver 130 via the RIS array block 120. The electromagnetic wave transmitted from the transmitting end 110 is reflected by the RIS and delivered to the receiving end 130. At this time, each RIS unit cell 121 changes the characteristic (phase) of the incident electromagnetic wave to 0 ° or 180 ° (ON/ It is reflected after converting to OFF state). It is an object of the present invention to define a state of each unit cell capable of delivering optimal power to a receiving end.

As shown in FIG. 1, a long-distance wireless power transmission system coordinate system model using RIS can be implemented. To this end, in one embodiment of the present invention, RF (Radio Frequency) wireless power transmission consisting of one transmitter having multiple antennas, one receiver having multiple antennas, and a RIS array block 120 having k RIS tiles 123 Conduct an analysis of the system. Here, the whole RIS means thinking by dividing it into several sub (partial) arrangements of the ‘tile’ concept.

로 표시되고 파장의 길이는 λ로 표시된다. The positions of the transmitting end 110 and the receiving end 130 are each represented by a 3D vector as follows. Electromagnetic waves (EM waves) that deliver wireless power are transmitted by a transmitter, reflected from a tile, and received by a receiver. The frequency of electromagnetic waves is

, and the length of the wavelength is represented by λ.

안테나 배열과

안테나 배열을 가지는 직사각형 평면 어레이 안테나로 구성한다. 여기서, N>M이고, M은 가로축(x축) 또는 세로축(y축)에 설치되는 서브 안테나의 갯수이고, N은 세로 또는 가로축에 설치되는 서브 안테나의 갯수이고 Tx는 송신단, Rx는 수신단이다. The transmitting end 110 and the receiving end 130 are each

antenna array

It consists of a rectangular planar array antenna with an antenna array. Here, N>M, M is the number of sub-antennas installed on the horizontal axis (x-axis) or vertical axis (y-axis), N is the number of sub-antennas installed on the vertical or horizontal axis, Tx is the transmitter, Rx is the receiver .

The transmitting end 110 and the receiving end 130 have a coordinate system in which the antenna arrays are arranged in a plane along the x-axis and the y-axis, and each single antenna element is indexed by (m,n) . m, n is a positive natural number.

로 정의할 때, 평면에서 송신단 (m,n) 인덱스에 해당하는 단일 안테나 구성요소의 위치(μ)는 아래와 같이 표현할 수 있다.The spacing of adjacent single antenna elements at the transmitting end 110 is in the x and y directions, respectively.

When defined as , the position (μ) of a single antenna element corresponding to the transmitter (m,n) index in the plane can be expressed as follows.

는, 원점을 중심으로 일정한 길이 J만큼의 균일한 격자 j번째 격자점을 의미한다. 또한, T는 전치 행렬을 나타낸다. M은 어레이 형태의 평면 안테나에서 가로로 놓인 단일 안테나 구성요소의 개수이고, N은 세로로 놓인 단일 안테나 구성요소의 개수이다. 예를들면, 송신 안테나를 이루는 단일 안테나 구성요소의 총개수는

이다. here,

Means the j-th lattice point of a uniform lattice of a certain length J centered on the origin. Also, T denotes a transposition matrix. M is the number of horizontally placed single antenna elements in an array type planar antenna, and N is the number of vertically placed single antenna elements. For example, the total number of single antenna elements that make up a transmit antenna is

am.

는 가로로 M개의 단일 안테나 구성요소를 가지는 송신용 평면 안테나에서 가로로 m번 째 단일 안테나 구성요소,

는 세로로 N개의 단일 안테나 구성요소를 가질 때, 세로로 n번 째에 있는 단일 안테나 구성요소를 가리킨다.

is the m-th single antenna element horizontally in a transmission planar antenna having M single antenna elements horizontally ,

When having N number of single antenna elements in a vertical direction, denotes a single antenna element in the n-th position in the vertical direction.

는 수학적 모델로써 J개를 가지는 어떠한 모델에서 j번 째에 있는 것을 가리킨다. 다음과 같이 정의할 수 있다

is a mathematical model and refers to the jth item in any model with J. can be defined as

Similarly, the position (μ) of a single antenna element corresponding to the (m,n) index of the receiving end in the plane can be expressed as follows.

는 가로로 M개의 단일 안테나 구성요소를 가지는 수신용 평면 안테나에서 가로로 m번 째 단일 안테나 구성요소,

는 세로로 N개의 단일 안테나 구성요소를 가질 때, 세로로 n번 째에 있는 단일 안테나 구성요소를 가리킨다.here,

is the m-th single antenna element horizontally in a reception planar antenna having M single antenna elements horizontally ,

When having N number of single antenna elements in a vertical direction, denotes a single antenna element in the n-th position in the vertical direction.

로 인덱싱되고, 타일k는

의 RIS 단위셀의 부분배열을 가진다.In the case of RIS having K tiles of a rectangular shape, each tile is

indexed by , and tile k is

has a subarray of RIS unit cells of

및

로 정의하면, RIS 어레이 블럭(120)에서의 RIS 단위셀

인덱스의 위치(μ)는 아래와 같이 표현된다.In the coordinate system of each RIS tile, the RIS unit cell is placed along the x-axis and y-axis of the xy plane. RIS unit cell spacing in the x and y direction respectively

and

If defined as, RIS unit cell in RIS array block 120

The position of the index (μ) is expressed as follows.

는 RIS 타일 K가 가로로 M개의 단위셀을 가질 때 가로로부터 m번 째 있는 단위셀이고,

는 RIS 타일 K가 세로로 N개의 단위셀을 가질 때 세로로부터 n번 째 있는 단위셀이다here,

is the mth unit cell from the horizontal when the RIS tile K has M unit cells horizontally,

is the nth unit cell from the vertical when the RIS tile K has N unit cells vertically

로 정의하고, 마찬가지로 RIS 타일(k)(123)의 원점과 수신단(130) 사이의 거리는

로 정의한다. The distance between the origin of the transmitter 110 and the RIS tile (k) 123

, and similarly, the distance between the origin of the RIS tile (k) 123 and the receiving terminal 130 is

is defined as

및

에 비해 충분히 작다. 이 조건이 충족되지 않는 환경이라고 해도 RIS 타일을 더 작은 크기의 RIS 타일로 나누어 생각할 수 있기 때문에 알고리즘상의 변경없이 다양한 환경에 적용시킬 수 있다.In the wireless power transmission system according to an embodiment of the present invention, it is assumed that the transmitter 110 and the receiver 130 are respectively located in a far-field with respect to the RIS tile 123. That is, the size of the RIS tile 123 is the distance between the transmitter and the receiver.

and

small enough compared to Even in an environment where this condition is not met, since the RIS tile can be considered as being divided into smaller RIS tiles, it can be applied to various environments without changing the algorithm.

및 방위각

으로 나타나고, RIS 타일(123)에서 송신단(110)까지의 방향은 고도각

및 방위각

로 표시된다.The direction from the transmitter 110 to the RIS tile 123 is the elevation angle

and azimuth

, and the direction from the RIS tile 123 to the transmitter 110 is the elevation angle

and azimuth

is indicated by

로 표현할 수 있다.

및

에 대해서 본 발명에서는 방향을 나타내는데, u-v 좌표를 사용한다.In the same way, the directional relationship between the receiving end 130 and the RIS tile 123 is

can be expressed as

and

In the present invention, direction is indicated, and uv coordinates are used.

로 표현되고, 송신단(110)에서 RIS 타일(123)까지의 방향의 u-v 좌표(S)는 다음과 같다. 여기서, T는 전치를 나타낸다.The uv coordinates of altitude θ and azimuth φ are

, and the uv coordinate (S) of the direction from the transmitter 110 to the RIS tile 123 is as follows. Here, T represents a transpose.

및

로 표시되는 다른 방향의 u-v 좌표도 같은 방식으로 정의 할 수 있다.

and

The uv coordinates of other directions, represented by , can be defined in the same way.

,

그리고

세 가지 매개 변수로 완전하게 정의할 수 있고, 마찬가지로 수신단(130)과 RIS 타일(123)의 관계는

,

그리고

로 정의된다. The spatial relationship between the transmitter 110 and the RIS tile 123 is

,

and

It can be completely defined by three parameters, and similarly, the relationship between the receiving end 130 and the RIS tile 123 is

,

and

is defined as

및

로 표시되고, 마찬가지로 송신단(110)와 수신단(130)에 대한 RIS 타일(123)의 단위 셀 이득은 각각

및

로 표시된다.Based on this spatial relationship, wireless power transfer modeling from a transmitter to a receiver through RIS tiles can be described. However, in the present invention, it is assumed that power transmitted between RIS tiles does not exist. The gains of the antenna elements of the transmitter 110 and the receiver 130 for the RIS tile 123 are

and

, and similarly, the unit cell gain of the RIS tile 123 for the transmitter 110 and the receiver 130 is

and

is indicated by

FIG. 2 is a perspective view and an equivalent circuit 230 of the RIS unit cells 111, 121, and 131 shown in FIG. Referring to FIG. 2, RIS is composed of very simple passive elements such as capacitors, inductors, and varactors, unlike conventional large-scale MIMO and phased array antennas composed of RF chains such as phase shifters, amplifiers, and attenuators. there is. The RIS unit cells 111 , 121 , and 131 may include a printed circuit board 210 and circuit patterns 220 , 221 , and 222 .

Parameters and volumes of components of the RIS unit cells 111, 121, and 131 shown in FIG. 2 are shown in the following table.

parameter volume (mm) W 36.2 h 1.7 a 16.61 b 12.88 c 12 d 7.5

A unit cell of the RIS tile 123 is modeled, and a control mechanism of each RIS tile 123 is described. Each unit cell is linearly polarized, and the E-fields of the incident and reflected waves coincide with the polarization of the unit cell. The incident free space wave is converted into a guided wave in a unit cell, and at this time, it is reflected by a load controllable with a normalized impedance (Z _L ). The reflected guided wave is radiated into the air in the form of a free space wave. Guided waves are reflected according to the equation:

Here, x and y are the powers of the incident and reflected guided waves of the unit cell, respectively, and Γ is the reflection coefficient expressed as

where Z _L is the normalized impedance.

The unit cell and controllable load are designed in such a way that the phase of the reflected wave is controlled by changing the reflection coefficient. Then the reflection coefficient can be expressed as:

Here, ξ means a phase shift. When configuring a controllable load with a varactor, the phase shift is continuous, whereas when a PIN diode is used as a controllable load, the phase shift is discrete. If the number of controlled states of a unit cell is represented by L, the lth state of the unit cell represents a phase-transformed state as shown below.

Here, L means the number of control states of a unit cell.

을 RIS 타일 k의 단위 셀(m,n)의 반사 계수로 정의한다. 하지만, 대규모 RIS 에서는 단위 셀이 매우 많기 때문에 각 단위 셀에 대한 최적의 반사 계수를 개별적으로 찾는 것은 비효율적이다. 따라서, 본 발명의 일실시예에서는 각 RIS 타일에 대해 높은 차원의 제어 매개 변수 도입을 통해 알고리즘을 제안한다.

is defined as the reflection coefficient of the unit cell (m, n) of the RIS tile k. However, in large-scale RIS, since there are so many unit cells, it is inefficient to individually find the optimal reflection coefficient for each unit cell. Therefore, in one embodiment of the present invention, an algorithm is proposed by introducing a high-dimensional control parameter for each RIS tile.

및 방위각

에 의해 결정되고, 이러한 제어 매개 변수를 설정하면 RIS 타일의 법선 방향에서 나오는 입사파가 고도각

및 방위각

방향으로 반사된다. 고도각

및 방위각

의 u-v 좌표는 다음과 같이 나타낼 수 있다. 이 때 RIS 타일 k의 방향 제어 매개 변수(c_k)는 아래와 같이 정의된다.Referring to FIG. 1, the direction of the electromagnetic wave reflected from the RIS tile 123 is the elevation angle

and azimuth

, and by setting these control parameters, the incident wave coming from the normal direction of the RIS tile

and azimuth

reflected in the direction elevation angle

and azimuth

The uv coordinates of can be expressed as: At this time, the direction control parameter (c _k ) of the RIS tile k is defined as follows.

In addition, the phase of the reflected wave (ie the reflected electromagnetic wave) is controlled by the phase control parameter w _k for the RIS tile 123 . The reflection coefficient of each unit cell at the time of continuous phase shift using the direction control parameter (c _k ) and the phase control parameter (w _k ) is defined as follows. The phase control parameter (w _k ) is any one value.

FIG. 3 is a block diagram of the transmitter 110 shown in FIG. 1 . Referring to FIG. 3, the transmitter 110 is connected to the sensor 301 and receives a transmission request, the control unit 310, and the first to kth control components 320-th generate electromagnetic waves according to the command of the control unit 310. 1 to 320-n), the antenna 330 including the first to nth antenna components 330-1 to 330-n, and the like. The sensor 301 is an IoT sensor, but other sensors are also possible.

In one embodiment of the present invention, the transmitter 110 is composed of a phased antenna array, and each antenna component 330-1 to 330-n has a phase shifter (not shown) for controlling the phase of the radiated electromagnetic wave. are placed All antenna components of the transmitter 110 transmit the same power, and this power value is defined as p.

및 방위각

로 표시된다. 송신단(110)의 방향 제어 매개 변수(q)는

및

의 u-v 좌표이다. 이를 수식으로 나타내면 다음과 같다.Similar to RIS control, the transmitting end is controlled by high-order control parameters. The direction of the transmitted electromagnetic wave is the elevation angle

and azimuth

is indicated by The direction control parameter (q) of the transmitting end 110 is

and

is the uv coordinate of If this is expressed as a formula, it is as follows.

는 방향 제어 매개 변수가 q일 때 송신단(110)의 단일 안테나 구성요소(m,n)에서 송신된 전자기파를 의미하고 아래와 같이 표현된다.

denotes an electromagnetic wave transmitted from a single antenna element (m, n) of the transmitter 110 when the direction control parameter is q and is expressed as follows.

The receiving end 130 is composed of an antenna array for receiving RF power from each antenna element. The RF power received at a single antenna element is converted to Direct Current (DC) power through a rectifier placed in each element, and the power is harvested through a DC coupling technique. If the RF-DC conversion function that maps the received RF power to the rectified DC power is defined as , and y _m,n is defined as the wave received at the antenna array (m,n) of the receiving end 130, the total received power P is expressed as:

Based on the model with the equations described above, the RF long-distance wireless power transmission system including the entire RIS is analyzed.

First, looking at the channel gain analysis between the single antenna elements 330-1 to 330-n of the transmitter 110 or the receiver 130 and the unit cell of the RIS tile 123, the channel gain between the two single antenna elements is generally (h) is given by

Here, d is the distance between two single antenna elements, and G ^A and G ^B represent the respective gains of the two single antenna elements. Based on the above equation, first, a channel gain between a single antenna element (i, j) of a transmitter and a unit cell (m, n) of the RIS tile 123 can be derived. The distance between a single antenna element and a unit cell in the far field is

및

로 바꾸면, 송신단(110)의 단일 안테나 구성요소(i,j)에서 RIS 타일(123)의 단위 셀(m,n)로의 채널 이득을 다음과 같이 유도할 수 있다.Plug Equation 16 into Equation 15 and obtain the antenna gain

and

, the channel gain from the single antenna element (i, j) of the transmitter 110 to the unit cell (m, n) of the RIS tile 123 can be derived as follows.

In a similar manner, the channel gain from the unit cell (m,n) of the RIS tile 123 to the single antenna elements (a,b) of the receiving terminal 130 can be derived as follows.

After being transmitted from the antenna element (i, j) of the transmitter 110 through Equations 11, Equation 15, and Equation 16, it is reflected from the unit cell (m, n) of the RIS tile 123 and the receiver 130 The channel gain into a single antenna component (a, b) of is derived as:

Finally, the electromagnetic wave signal received by the single antenna component of the receiving end 130 is as follows.

는 송신단(110)의 단일 안테나 구성요소(i,j)에서 수신단(130)의 단일 안테나 구성요소(a,b)로의 직접 전달되는 채널 이득을 의미한다.here,

Means a channel gain directly transferred from the single antenna element (i, j) of the transmitting end 110 to the single antenna element (a, b) of the receiving end 130.

In fact, energy can be efficiently transferred when power is transmitted by forming and steering a beam in the antenna array of the transmitter 110 and the RIS tile 123 . Based on Equation 10, analysis of beamforming and steering may also be performed. To represent this:

및

는 상기 RIS 타일(123)에 대한 상기 송신단 및 상기 수신단의의 안테나 이득을 나타내고,

및

는 상기 송신단 및 상기 수신단에 대한 상기 RIS 타일의 단위셀 이득이고, (a,b)는 수신단(130)의 단일 안테나 구성요소를 나타내고, c_k는 방향 제어 매개 변수이고, w_k는 위상 제어 매개 변수이고,

,

그리고

는 상기 수신단과 상기 RIS 타일 사이의 공간적 관계(spatial relationship)이고,

,

그리고

상기 송신단과 상기 RIS 타일 사이의 공간적 관계이다.Here, h is the channel gain from a single antenna component (i, j) to the second unit cell (m, n) of the RIS tile, and x _{i, j} (q) is the transmit end when the direction control parameter is q Means an electromagnetic wave transmitted from a single antenna element (i, j), λ is the length of the wavelength,

and

Represents the antenna gain of the transmitting end and the receiving end for the RIS tile 123,

and

Is the unit cell gain of the RIS tile for the transmitting end and the receiving end, (a, b) represents a single antenna element of the receiving end 130, c _k is a direction control parameter, and w _k is a phase control parameter is a variable,

,

and

Is a spatial relationship between the receiving end and the RIS tile,

,

and

It is a spatial relationship between the transmitter and the RIS tile.

The above expression can be simplified as follows.

는 수신단(130)에서 수신된 전자기파의 크기와 위상을 나타내고, 이는 송신단, RIS 타일, 그리고 수신단의 단일 안테나 구성요소(a,b)까지의 전체 거리와 연관이 있고 아래와 같이 표현할 수 있다.here,

Represents the magnitude and phase of the electromagnetic wave received at the receiving end 130, which is related to the total distance to the transmitting end, the RIS tile, and the single antenna element (a, b) of the receiving end, and can be expressed as follows.

는 RIS 타일(123)의 빔 조향 기능을 나타내고, 이는 u-v 좌표에서의 방향벡터

로의 빔 이득(beam gain)을 의미한다.

는 아래와 같이 정의할 수 있다.Also in Equation 22

Represents the beam steering function of the RIS tile 123, which is the direction vector in uv coordinates

It means the beam gain of Rho.

can be defined as below.

는 다음과 같은 주기 sinc 함수이다.here,

is the periodic sinc function as

는 가 0일 때, 최대가 되므로

는 가 0벡터일 때 최대 이득

를 가진다. 이는 곧 RIS 타일(123)에서 수신단(130)으로의 빔 이득(

)은 RIS 타일(123)의 방향 제어 매개 변수를 로 설정 할 때 최대화됨을 의미한다.periodic sinc function

is maximum when is 0, so

is the maximum gain when is a zero vector

have This is the beam gain from the RIS tile 123 to the receiving end 130 (

) means that it is maximized when the direction control parameter of the RIS tile 123 is set to .

는 송신단의 빔 조향 기능을 나타내며 다음과 같이 정의된다.Likewise

represents the beam steering function of the transmitting end and is defined as follows.

의 v가 0벡터일 때 최대 이득

을 가지므로, 송신단(130)에서 RIS 타일(123)까지의 빔 이득(

)은 송신단의 방향 제어 매개 변수가

일 때 최대화된다.

Maximum gain when v of is a 0 vector

Since it has, the beam gain from the transmitter 130 to the RIS tile 123 (

) is the direction control parameter of the sending end

is maximized when

In Equation 23, the signals received from the single antenna elements (a, b) of the transmitting end can be rearranged as follows.

는 RIS 타일을 거치지 않고 수신단의 안테나 구성요소(a,b)로 직접 전송되는 전력을 의미한다.here,

Denotes power transmitted directly to the antenna elements (a, b) of the receiving end without passing through the RIS tile.

를 다음과 같이 정의한다.

is defined as:

The total received power of the receiving end can be calculated through the total received power P defined above and Equation 27.

이 높다.The equation of Equation 27 can be intuitively interpreted as follows. The transmitting end controls the direction control parameter q to steer the beam to the selected RIS tile. At this time, the beam gain from the transmitter to the selected RIS tile

is high

The RIS tile 123 reflects the beam received from the transmitter in a specific direction according to a direction control parameter c _k .

로 설정해야 반사된 빔을 수신기로 조향할 수 있다.At this time. The RIS tile 123 has a direction control parameter c _k

must be set to steer the reflected beam to the receiver.

The receiver receives both reflected beams from the various RIS tiles and electromagnetic waves transmitted directly from the transmitter. At this time,

에 따라 달라지며 이는 송신단(110)으로부터 직접 전달받은 위상과 일치하지 않는다. 따라서, 각 RIS 타일은 위상제어 변수 w_k의 조절을 통해 모든 파동이 수신단(130)에서 최적으로 결합되도록 수신단(110)에서 빔의 위상을 정렬해야 한다.The beam phase of the RIS tile 123 is

It depends on and does not match the phase directly received from the transmitter 110. Therefore, each RIS tile needs to align the phases of the beams at the receiving end 110 so that all waves are optimally combined at the receiving end 130 through adjustment of the phase control variable w _k .

FIG. 4 is a detailed block diagram of the control unit 310 shown in FIG. 3 . Referring to FIG. 4 , the control unit 310 includes a receiving module 410 receiving a transmission request from the sensor 301, a synchronization module 420 for synchronizing RIS tiles, analyzing received power values for beam codes of each transmitting end, and It may include a calculation module 430 for deriving an optimal value, a decision module 440 for determining an optimal on/off pattern after selecting an optimal transmitter beam pattern, and determining an optimal RIS phase adjustment value.

The terms "synchronization module 420", calculation module 430", and "determination module 440" described in the drawings refer to a unit that processes at least one function or operation, which is implemented as software and/or hardware. In hardware implementation, an ASIC (application specific integrated circuit) designed to perform the above functions, a DSP (digital signal processing), a PLD (programmable logic device), an FPGA (field programmable gate array), a processor, It can be implemented as a microprocessor, other electronic unit or a combination thereof In software implementation, software component (element), object-oriented software component, class component and task component, process, function, property, procedure, may include subroutines, segments of program code, drivers, firmware, microcode, data, databases, data structures, tables, arrays and variables Software, data, etc. may be stored in memory and executed by a processor The memory or processor may employ various means well known to those skilled in the art.

5 is a flowchart illustrating a process of wireless power transmission using RIS according to an embodiment of the present invention. Referring to FIG. 5 , when the transmitter 140 receives an energy transmission request from a sensor 301 such as an IoT device, beam scanning starts from the first subarray of the RIS array block 120 (steps S510 and S520).

To elaborate, a beam scanning technique is performed to achieve optimal power transmission efficiency based on beam scanning. An embodiment of the present invention proposes a beam scanning technique that estimates appropriate control parameters and phase control parameters of a RIS tile and direction control parameters of a transmitter using only received power.

로 나타낼 수 있다. l번째 스캔된 점에서 RIS 타일(123)의 방향 제어 c_k,l는 아래와 같이 정의된다. To scan the coordinates, generate beam codes that fit the M x N array. At this time, N _u and N _v are the number of points to be scanned in the u and v directions, respectively. The total number of patterns to be scanned is

can be expressed as The direction control c _k,l of the RIS tile 123 at the lth scanned point is defined as follows.

,

이고 u,v방향의 스캐닝 단계별 크기는 각각

이다.here ,

,

and the size of each scanning step in the u and v directions is

am.

으로 향하게 하도록 RIS 타일(123)의 구성요소(m,n)에 대한 반사 신호는 아래와 같다. beam point

The reflected signal for the components (m,n) of the RIS tile 123 to direct to is as follows.

A transmission signal for each single antenna element of the transmitter 110 at the 1-th scanned point can be defined in the same way. The reflection coefficient matrix of the RIS tile 123 is expressed as follows using c _k,l and w _k .

로 RIS 타일을 스캔한다. 이 후 k번째 타일이 스캔되었을 때, 전체 RIS의 반사 계수 행렬

을 다음과 같이 한다. In order to obtain the optimal direction control and phase control values of the RIS tile 123, while other tiles are fixed

Scan the RIS tile with After this, when the kth tile is scanned, the reflection coefficient matrix of the entire RIS

as follows:

로 M x N 행렬에 대한 벡터화이다. 끝으로, 수학식 19을 아래와 같이 다시 나타낼 수 있다.At this time,

is a vectorization of an M x N matrix. Finally, Equation 19 can be re-expressed as follows.

는 아다마르 곱이고,

는 각각 송신기에서 RIS로의 채널, RIS에서 수신단 으로의 채널, 직접 전달되는 채널에서 채널 이득의 행렬 형태이다. x(q)는 송신단에서 방향 제어 매개 변수가 q일 때 송신되는 신호의 행렬 형태이다.here,

is the Hadamard product,

is a matrix form of the channel gain in the channel from the transmitter to the RIS, the channel from the RIS to the receiver, and the channel directly transmitted. x(q) is a matrix form of a signal transmitted when the direction control parameter is q at the transmitting end.

와 송신단의 방향 제어 매개 변수 q 에 대한 수신 전력은 아래와 같다.Reflection coefficient matrix in RIS

and the received power for the direction control parameter q of the transmitter is as follows.

Here, ζ means RF-DC (Radio-Frequency) changed efficiency.

As in the above analysis, the beam scanning algorithm flowchart can be performed as shown in FIG. 5 using only received power information.

, 모든 RIS 타일에 대한 최적의 위상 제어

와 송신단(130)의 최적 방향 제어τ을 출력한다. 매 송신단 빔 코드i에 대하여,

빔 코드들 및 위상 제어 0,

을 이용하여 RIS 타일 j를 스캔한다(단계 S530,S540,S550). Optimal direction control

, optimal phase control for all RIS tiles

and the optimal direction control τ of the transmitter 130 are output. For every transmitter beam code i,

beam codes and phase control 0;

RIS tile j is scanned using (steps S530, S540, and S550).

로 표시된다. P_t의 평균값은

로 나타낸다. 최적의 위상 제어

은 위상제어가 더 높은 수신 전력을 전달할 때마다 갱신된다.Then, the one direction control that gives the largest difference to the received power is selected, which

is indicated by The average value of P _t is

represented by Optimal phase control

is updated each time the phase control delivers a higher received power.

Optimum direction control and phase control of RIS tile j are updated in the reflection coefficient matrix G ₀ . Optimal phase control can be obtained by repeating two downward trends. An RIS tile with highly improved received power is determined through optimal values obtained by controlling the RIS tile j.

와 위상 제어에 대한 벡터를 반환한다. 최적의 효율을 나타낸 송신단 측 빔 S^Tx 와 그에 따른 RIS 타일 S^Tile에 대한 벡터값은 이후 스캐닝에서 사용된다(단계 S560,S570,S571,S580,S581,S590).After obtaining all optimal parameters of the RIS tile, the maximum transmit power for each transmit beam i can be obtained. After the scan process is finished, a transmit beam having the highest received power is selected. The algorithm controls the τ value, the optimal RIS direction

and returns a vector for phase control. The vector values for the transmitter-side beam S ^Tx and the resulting RIS tile S ^Tile showing the optimal efficiency are used in subsequent scanning (steps S560, S570, S571, S580, S581, and S590).

The receiving terminal 130 records the received power according to the on/off pattern of each unit cell, and records and stores the maximum received power among them and the corresponding beam index of the partial array currently being scanned. This information is transmitted to the transmitter and transmitted to RIS to update the optimal beam code (ON/OFF pattern of each unit cell) for the first subarray. Then, the next subarray is scanned in turn until all subarrays are scanned, and as a result, the optimal power is transmitted to the receiving end through the optimal ON/OFF pattern for the entire RIS.

6 is a graph showing received power for each beam index according to an embodiment of the present invention, FIG. 7 is a phase control graph of a transmitter according to an embodiment of the present invention, and FIG. 8 is an embodiment of the present invention. It is a graph showing the RIS optimal pattern according to . 6 to 8 are simulation results for verifying an embodiment of the present invention. In the simulation, a tile composed of 4x4 unit cells and a large-area 1-bit-RIS composed of 100 of those tiles were used. At this time, the coordinates of RIS are located at the origin (0,0,0), the transmitter composed of 4x4 antenna is located at (3m, -4m, 2m), and the 2x2 receiver is located at (5m, 2m, -1m). It is assumed that no channel is passed directly from the transmitter to the receiver.

As shown in FIG. 6, the highest received power can be obtained in the 13th transmission beam after the first scanning (611). It has a power gain of about 25 dB when using the proposed technique (621) than when the RIS is in the OFF state (622).

In the case of FIGS. 7 and 8 , it can be seen that the transmission phase of the transmitter and the reflection phase of the RIS are properly obtained.

On the other hand, for the practical use and commercialization of long-distance wireless power transmission technology, the following items are required.

1) Efficiency and distance increase: Due to the nature of RF wireless power transmission, efficiency is relatively low, and even when charging low-power IoT devices, 10-20 meters can be considered the current maximum distance. Even now, it can be applied to many applications (e.g., charging sensors installed in hard-to-reach places), but improvement in efficiency/distance is required to expand the application field. In addition, when an obstacle or a person is located on the path, there is a major drawback in that the power transmission efficiency drops sharply. Due to the straightness of the electromagnetic wave, a shadow area is created in a place where a line of sight (LOS) is not maintained.

2) Human safety: In consideration of the adverse effects that electromagnetic waves can have on the human body, additional technology is needed to ensure human safety when used in an environment where people exist. For example, when a person is detected, transmission is stopped or the beam is diverted in a different direction to ensure human safety to speed up commercialization.

3) Device price: In the case of phased array antennas used as transmitters in long-distance wireless power transmission, the production cost is very high, which is an obstacle to commercialization. When implemented based on a commercially available IC (Integrated Circuit), there is a problem in that the price is increased, so efforts are required to lower the cost by manufacturing an IC dedicated to the transmitter and receiver.

A solution to the above three problems can be proposed by introducing the reflective reconfigurable intelligent surface (RIS) technology proposed in an embodiment of the present invention to a long-distance wireless power transmission system.

First, RIS (reconfigurable intelligent surface) technology It is implemented with numerous unit cells, and each unit cell of such RIS can change characteristics such as phase, power, and polarization of an electromagnetic wave passing through or being reflected.

RIS technology means a technology that can control the reaction of the entire RIS by adding a variable element such as a PIN diode or a varactor to each unit cell so that the characteristics of the unit cell change as voltage is applied. Since RIS can freely transform electromagnetic waves applied from the outside, it has high potential value for wireless communication as well as long-distance wireless power transmission.

9 is a graph showing locations of a transmitting end, a receiving end, and RIS according to an embodiment of the present invention. That is, in FIG. 9 , when configuring a test bed for simulation, the distance between the transmitter/receiver and RIS is about 2 m, and the distance between the transmitter and receiver is 1 m.

10 is a graph showing the relationship of distance versus power transmission efficiency according to an embodiment of the present invention. Referring to FIG. 10 , it is a relationship between distance and power transfer efficiency according to the size of a partial array of RIS tiles. As shown in FIG. 10, when there is no RIS, the lowest efficiency is shown, and the efficiency of power transmission is different depending on the size and distance of the array.

In addition, the steps of a method or algorithm described in connection with the embodiments disclosed herein are implemented in the form of program instructions that can be executed through various computer means such as a microprocessor, processor, CPU (Central Processing Unit), etc. It can be recorded on any available medium. The computer readable medium may include program (instruction) codes, data files, data structures, etc. alone or in combination.

The program (command) code recorded on the medium may be specially designed and configured for the present invention, or may be known and usable to those skilled in computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tapes, optical media such as CD-ROMs, DVDs, and Blu-rays, and ROMs and RAMs ( A semiconductor storage element specially configured to store and execute program (instruction) codes such as RAM), flash memory, or the like may be included.

Here, examples of the program (command) code include high-level language codes that can be executed by a computer using an interpreter, as well as machine language codes such as those produced by a compiler. The hardware devices described above may be configured to act as one or more software modules to perform the operations of the present invention, and vice versa.

100: wireless power transmission system
110: transmitter 111: first RIS (Reconfigurable Intelligent Surface) unit cell
120: RIS array block 121: second RIS unit cell
122 Substrate 123 RIS tile
130: receiving terminal 131: third RIS unit cell
301: sensor
310: control unit
320-1 to 320-n: first to nth control components
330: antenna
330-1 to 330-n: first to nth unit antenna elements
410: receiving module 420: synchronization module
430 calculation module 440 decision module

Claims (18)

a transmitter 110 having a first antenna composed of a plurality of first RIS (Reconfigurable Intelligent Surface) unit cells 111;
a RIS array block 120 configured by partially arranging a plurality of rectangular RIS tiles 123 composed of a plurality of second RIS unit cells 121;
A receiving end 130 having a second antenna composed of a plurality of third RIS unit cells 131; includes,
The transmitter 110 defines each unit cell adjustment value for beam forming and steering through channel information analysis between the transmitter 110, the RIS array block 120, and the receiver 130, and each unit A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that beam scanning is performed for each subarray based on a cell adjustment value.
According to claim 1,
The beam forming is a wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that using the received power level detection at the receiving end (130).
According to claim 1,
The first antenna and the second antenna are rectangular planar array antennas in which a plurality of single antenna elements (330-1 to 330-n) are arranged in the x-axis and the y-axis to have a coordinate system. A wireless power transmission system having a beam scanning algorithm based on received power for
According to claim 3,
The position (μ) of the first RIS unit cell 111 (m, n) index of the transmitter 110 and the (m, n) index of the third RIS unit cell 131 of the receiver 130 are respectively Equation

and

(here,

are adjacent single antenna element spacings in the x and y directions, respectively, Tx denotes the transmitting end, Rx denotes the receiving end, M, N, m, n are positive natural numbers,

Means the j-th lattice point of a uniform lattice of a certain length J centered on the origin, T means a transposition matrix,

,

is the m-th single antenna element horizontally in a transmission planar antenna having M single antenna elements horizontally ,

When has N single antenna elements vertically, refers to the single antenna element in the nth position vertically,

is the m-th single antenna element horizontally in a reception planar antenna having M single antenna elements horizontally ,

A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that defined as a single antenna element vertically n when having N single antenna elements vertically) .
According to claim 3,
The tile k indexed by the RIS tile 123 is

has a partial arrangement of the second RIS unit cell 121 of, and the position (μ) of the (m, n) index of the second RIS unit cell 121 is Equation

(here,

,

and

are the RIS unit cell spacing defined in the x and y directions, respectively,

is the mth unit cell from the horizontal when the RIS tile K has M unit cells horizontally,

is the nth unit cell from the vertical when the RIS tile K has N unit cells vertically). Wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that.
According to claim 5,
The size of the RIS tile 123 is the distance between the origin of the transmitter 110 and the RIS tile 123 (

) and the distance between the origin of the RIS tile 123 and the receiving end 130 (

A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that it is smaller than ).
According to claim 5,
The uv coordinate (S) of the direction from the transmitter 110 to the RIS tile 123 is expressed by Equation

(here,

and

are elevation angles and azimuth angles from the transmitter 110 to the RIS tile 123, respectively;

and

is an elevation angle and an azimuth angle from the RIS tile 123 to the transmitter 110, and T is a transpose), characterized in that defined as), a wireless power transmission system having a beam scanning algorithm based on received power for achieving transmission efficiency .
According to claim 5,
A control parameter for control is set for the RIS tile 123, and the control parameter is composed of a direction control parameter (c _k ) and a phase control parameter (w _k ),
The direction control parameter (c _k ) is expressed by Equation

(here,

and

are the elevation and azimuth angles of electromagnetic waves reflected from the IS tile 123, respectively, and T is a transposition). A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that.
According to claim 8,
Reflection coefficient of the index of the second unit cell 121 (m,n) of the RIS tile 123 when the continuous phase shift is performed using the direction control parameter (c _k ) and the phase control parameter (w _k )

) is the equation

A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that defined as.
According to claim 5,
The direction control parameter (q) of the transmitter 110 is Equation

(here,

and

is an elevation angle and an azimuth angle of the transmitted electromagnetic wave, respectively).
According to claim 10,
When the direction control parameter (q) is the electromagnetic wave transmitted from the single antenna element (m, n) of the transmitting end 110 (

) is the equation

(Where, p is the transmitted power value,

A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that defined as).
According to claim 5,
The distance (d) between the single antenna element (i, j) of the transmitter 110 and the second unit cell 121 (m, n) of the RIS tile 123 is expressed by Equation

(here,

,

and

Is a spatial relationship between the transmitting end 110 and the RIS tile 123, Tx means a transmitting end, Rx means a receiving end, M, N, m, n, i, j, a , b) is a positive natural number) A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that defined as.
According to claim 12,
Analysis of the beam forming and steering is expressed by Equation

(Where, h is the channel gain from a single antenna element (i, j) to the second unit cell (m, n) of the RIS tile, and x _{i, j} (q) is the transmitting end when the direction control parameter is q Means an electromagnetic wave transmitted from a single antenna component (i, j) of , λ is the length of the wavelength,

and

Represents the antenna gain of the transmitting end and the receiving end for the RIS tile 123,

and

Is the unit cell gain of the RIS tile for the transmitting end and the receiving end, (a, b) represents a single antenna element of the receiving end 130, c _k is a direction control parameter, and w _k is a phase control parameter is a variable,

,

and

Is a spatial relationship between the receiving end and the RIS tile,

,

and

A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that achieved through a spatial relationship between the transmitter and the RIS tile).
According to claim 13,
In the case of the steering, the RIS tile 123 determines the direction control parameter c _k

Wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that set to.
According to claim 13,
The RIS tile 123 achieves transmission efficiency, characterized in that the phase of the beam at the receiving end 110 is aligned so that all waves are combined at the receiving end 130 through adjustment of the phase control parameter (w _k ) A wireless power transmission system having a beam scanning algorithm based on received power for
According to claim 1,
The direction control (c _k ) of the RIS tile 123 at the point scanned according to the beam scanning is expressed by Equation

(here,

,

, and the size of each scanning step in the u and v directions is

A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that made through.
According to claim 1,
The receiving end 120 records the received power according to the on/off pattern of the second RIS unit cell 121 and a beam index corresponding to the received power and a partial array currently being scanned, and the received power and the A wireless power transmission system having a received power-based beam scanning algorithm for achieving transmission efficiency, characterized in that for transmitting beam index information to the transmitter (110).
A transmitter 110 having a first antenna made up of a plurality of first RIS (Reconfigurable Intelligent Surface) unit cells 111, and a plurality of rectangular RIS tiles 123 made up of a plurality of second RIS unit cells 121. In a wireless power transmission method of a wireless power transmission system including a RIS array block 120 configured in a partial array, and a receiving terminal 130 having a second antenna composed of a plurality of third RIS unit cells 131,
(a) Defining, by the transmitting end 110, each unit cell adjustment value for beam forming and steering through channel information analysis between the transmitting end 110, the RIS array block 120, and the receiving end 130 ;and
(b) the transmitter 110 performing beam scanning for each subarray based on the unit cell adjustment value; wireless power transmission method characterized in that it comprises a.

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