KR20170029454A - Method for transmitting and receiving multi-mode signal using uniform circular array antenna, and apparatuses performing the same - Google Patents

Abstract

Disclosed are a method for transmitting and receiving a multi-mode signal using a UCA antenna, and apparatuses performing the same. According to an embodiment of the present invention, the method for transmitting a signal comprises the steps of: spreading each of multi-mode signals; and mapping the spread multi-mode signals to discrete Fourier transform (DFS) beams.

Description

METHOD FOR TRANSMITTING AND RECEIVING MULTI-MODE SIGNAL USING UNIFORM CIRCULAR ARRAY ANTENNA, AND APPARATUSES PERFORMING THE SAME Technical Field [1] The present invention relates to a multi-

The embodiments described below relate to a method for transmitting and receiving a multimode signal using a UCA antenna, and devices for performing the same.

OAM (Orbital Angular Momentum) is one of the momentum of all electromagnetic waves together with Linear Momentum (LM) and Spin Angular Momentum (SAM).

The LM is able to transmit and receive only one channel and can transmit two polarizations and is used for satellite communication.

On the other hand, OAM has been theoretically proved to be able to transmit infinite modes without interference, and studies have been actively conducted on techniques for generating, receiving, and decoding the OAM multi-mode.

In a system using a pair of UCA (Uniform Circular Array) antennas using N transmit antenna elements and N receive antenna elements in a transmitter to generate an OAM multi-mode signal in a line-of-sight (LoS) environment, Requires very high transmit power and dynamic range of the receiver to transmit OAM multimode signals over long distances.

Embodiments can provide a technique of transmitting and receiving a multi-mode signal through a spatial spreading method using a UCA antenna.

A method of transmitting a multi-mode signal according to an embodiment may include spreading each of the multi-mode signals and mapping spreading multi-mode signals to Discrete Fourier transform (DFT) beams.

The spreading step may include spreading the multimode signals through a spreading matrix.

Wherein the step of spreading comprises:

And computing the spread multimode signals using the multimode signals using Equation (34).

The mapping step may comprise modulating the spread multi-mode signals using a DTF matrix.

The spreading matrix may be a unitary matrix including a DFT matrix.

An OAM transmitter in accordance with one embodiment may include a spreading module that spreads each of the multimode signals and a modulator that maps the spread multimode signals to Discrete Fourier transform (DFT) beams.

The spreading module may spread the multi-mode signals through a spreading matrix.

The spreading module may calculate the spread multimode signals using the multimode signals using Equation (35).

The modulator may modulate the spread multimode signals using a DTF matrix.

The spreading matrix may be a unitary matrix including a DFT matrix.

1 schematically shows a structure of a transmitting and receiving UCA antenna.
Fig. 2 schematically shows a communication system including the transmitting and receiving UCA antenna shown in Fig.
3 shows a far-field pattern of an OAM mode transmission signal using a UCA antenna with four antenna elements.
Fig. 4 shows the intensity of a radio wave appearing on the plane perpendicular to the traveling direction of the wave in the z-axis from the transmitting UCA antenna.
5 schematically illustrates a communication system according to one embodiment.
FIG. 6 is a conceptual diagram for transmitting multimode signals through the spatial spreading scheme of the OAM transmitter shown in FIG.
FIG. 7 shows a far field pattern for each mode that occurs when a spatial spreading scheme according to an embodiment is applied to a UCA antenna having four elements.
FIG. 8 shows a result of simulating the SER performance of each mode for the conventional method and the spatial spreading method.
FIG. 9 shows a result of simulating the integrated SER performance for all modes with respect to the existing UCA OAM scheme and spatial spreading scheme.

It is to be understood that the specific structural or functional descriptions of embodiments of the present invention disclosed herein are presented for the purpose of describing embodiments only in accordance with the concepts of the present invention, May be embodied in various forms and are not limited to the embodiments described herein.

Embodiments in accordance with the concepts of the present invention are capable of various modifications and may take various forms, so that the embodiments are illustrated in the drawings and described in detail herein. However, it is not intended to limit the embodiments according to the concepts of the present invention to the specific disclosure forms, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present invention.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms may be named for the purpose of distinguishing one element from another, for example without departing from the scope of the right according to the concept of the present invention, the first element being referred to as the second element, Similarly, the second component may also be referred to as the first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms " comprises ", or " having ", and the like, are used to specify one or more of the features, numbers, steps, operations, elements, But do not preclude the presence or addition of steps, operations, elements, parts, or combinations thereof.

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 this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning of the context in the relevant art and, unless explicitly defined herein, are to be interpreted as ideal or overly formal Do not.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. However, the scope of the patent application is not limited or limited by these embodiments. Like reference symbols in the drawings denote like elements.

A module in this specification may mean hardware capable of performing the functions and operations according to the respective names described in this specification and may mean computer program codes capable of performing specific functions and operations , Or an electronic recording medium, e.g., a processor or a microprocessor, equipped with computer program code capable of performing certain functions and operations.

In other words, a module may mean a functional and / or structural combination of hardware for carrying out the technical idea of the present invention and / or software for driving the hardware.

1 schematically shows a structure of a transmitting and receiving UCA antenna.

Referring to FIG. 1, a transmit / receive antenna structure for generating an Orbital Angular Momentum (OAM) multi-mode may include a UCA (Uniform Circular Array) antenna structure. For example, a UCA antenna structure may include a transmitting UCA antenna and a receiving UCA antenna.

The radius of the transmitting UCA antenna is RTX, the radius of the receiving UCA antenna is RRX, and the distance between the transmitting UCA antenna and the receiving UCA antenna may be D.

It is assumed that the antenna elements of the transmitting UCA antenna are all arranged at equal intervals on the x-y plane.

이고, 수신 UCA 안테나에 포함된 i-th 안테나 소자의 UCA 면의 각도는

일 수 있다. 그러면, 송신 UCA 안테나의 j-th 안테나 소자와 수신 UCA 안테나의 i-th 안테나 소자 사이의 거리 d_i,j는 수학식 1을 통해 표현될 수 있다.At this time, the angle of the UCA plane of the j-th antenna element included in the transmission UCA antenna is

, And the angle of the UCA plane of the i-th antenna element included in the reception UCA antenna is

Lt; / RTI > Then, the distance d _{i, j} between the j-th antenna element of the transmitting UCA antenna and the i-th antenna element of the receiving UCA antenna can be expressed by Equation (1).

는 수학식 2와 같이 정의되는 값으로서, i와 j의 차(즉, i-j)에 의해서만 결정될 수 있다.here,

Is a value defined by Equation (2), and can be determined only by the difference between i and j (ij).

도 마찬가지로 그 차이(difference가) 같은 {i, j}에 대하여 같은 값을 가질 수 있다.therefore,

Can also have the same value for {i, j} as the difference.

Meanwhile, when the distance d _{i, j} between the j-th antenna element of the transmitting UCA antenna and the i-th antenna element of the receiving UCA antenna is expressed as Equation 1, -th The channel between the antenna element and the i-th antenna element of the receiving UCA antenna can be expressed as Equation (3).

Assuming an omni-directional antenna element in which the beam pattern? Of the antenna element is independent of i, j, a UCA pair channel for a narrow band signal having a specific wave length The response can only be determined by the distance between these antenna elements. The channel matrix H can be expressed as Equation (4).

The channel matrix H may be a circulant matrix.

Fig. 2 schematically shows a communication system including the transmitting and receiving UCA antenna shown in Fig.

Referring to Figures 1 and 2, the communication system 10 may be a communication system using a UCA antenna structure. For example, the communication system 10 may be an OAM transmission system.

The communication system 10 can simultaneously transmit N mode signals using the UCA channel represented by Equation (4), i.e., the channel matrix H. [ That is, the UCA antenna structure of the communication system 10 may be a structure capable of simultaneously transmitting N modes using a UCA antenna having N antenna elements on the transmitting side and the receiving side.

The derivation procedure for the transmitter side and the receiver side, i.e., the transmitter and receiver structure of the communication system 10, can be described as follows.

로 정의될 수 있다. 수신 UCA 안테나의 N개 안테나 소자에서 발생하는 부가 백색 가우스 잡음(Additive White Gaussian Noise(AWGN))이

일 때, 수신 신호 벡터는 수학식 5와 같이 표현될 수 있다.The signal vector transmitted to the N antenna elements of the transmitting UCA antenna and the signal vector received to the N antenna elements of the receiving UCA antenna are

. ≪ / RTI > Additive White Gaussian Noise (AWGN), which occurs in the N antenna elements of the receiving UCA antenna,

, The received signal vector can be expressed by Equation (5).

로 분해될(decompose) 수 있다.When the NxN channel matrix H has a circularity, the channel matrix H is a complex diagonal matrix having an N-point Discrete Fourier transform (DFT) matrix Q and a complex element as shown in Equation (6)

As shown in FIG.

는 수학식 7과 같이 다시 표현될 수 있다.Then, the reception signal < RTI ID = 0.0 >

Can be rewritten as Equation (7).

를 DFT 매트릭스로 전처리(preprocessing)한 신호

, 즉

일 때, 수학식 7의 수신 신호

는 다시 수학식 8과 같이 표현될 수 있다.Transmit signal vector

Is preprocessed with a DFT matrix

, In other words

The received signal < RTI ID = 0.0 >

Can be expressed as Equation (8).

를 인버스(inverse) DFT로 후처리(postprocessing)한 신호를

이라고 할 때,

은 수학식 9와 같이 표현될 수 있다.

Into an inverse DFT to generate a postprocessed signal

In this case,

Can be expressed by Equation (9).

일 수 있다. 따라서,

의 추정(estimate)이 가능한(available) 경우, 수신기, 예를 들어 수신기의 검출기(detector)는

로부터

를 검파(detection)할 수 있다.here,

Lt; / RTI > therefore,

A receiver, e.g., a detector of the receiver,

from

Can be detected.

FIG. 3 shows a far-field pattern of an OAM mode transmission signal using a UCA antenna having four antenna elements, and FIG. 4 shows a far- Indicates the intensity of radio waves.

Referring to FIGS. 1 to 4, FIG. 3 illustrates a case where a UCA antenna, for example, a UCA antenna is laid side by side on an xy plane, that is, a z component of a position vector of all antenna elements of a UCA antenna Is zero (0). Figure 4 shows the field strength appearing in a circular plane with a radius of 10 [Lambda], which is perpendicular to the z-axis centered at (0, 0, 100) at a distance of 100 m from the transmitting UCA antenna in the z-axis.

As shown in FIG. 3, the mode 0 pattern is formed in the z-axis direction, and the field intensity appears strongly at the receiving point on the z-axis. Since the mode signals other than the mode 0 have no pattern in the z-axis direction, when the receiving point on the z-axis is far from the transmitter, the strength (or intensity) of the field formed near the receiving antenna is very small . This can be confirmed from FIG. 4 for the received radio wave intensity.

As shown in FIG. 4, the mode 0 indicates a strong field even at a transmission / reception distance of 100 m, while the remaining modes have a relatively low field intensity (for example, as shown in FIG. 4 Red means that the radio wave intensity is strong, and blue means that the radio wave intensity is weak).

This characteristic observed from the above-described beam pattern of the transmission signal, for example, the OAM multimode signal and the field strength, can be verified as follows by analyzing the channel capacity for each mode.

는 그 대각선 요소(diagonal element)들이

인 대각선 행렬(diagonal matrix)이고,

는 수학식 6을 통해 수학식 10과 같이 표현될 수 있다.In Equation (9)

Diagonal elements < RTI ID = 0.0 >

Diagonal matrix < RTI ID = 0.0 >

Can be expressed as Equation (10) through Equation (6).

From this, the received signal for mode k can be expressed as Equation (11).

The channel capacity for mode k may be expressed as Equation (12).

로 정의할 때, 수학식 11의

는 수학식 10을 통해 수학식 13과 같이 표현될 수 있다.Let the k-th column vector of the Q matrix be

, Equation (11)

Can be expressed by Equation (13) through Equation (10).

는 수학식 14와 같이 근사적으로 표현될 수 있다.When the transmission / reception distance D is much larger than the radius R _TX of the transmission UCA antenna,

Can be approximated as shown in Equation (14).

인 조건에서 모드 0이외의 모드들의 채널 용량은 0으로 근사화될 수 있다.therefore,

The channel capacity of modes other than mode 0 can be approximated to zero.

The reason why the channel capacity for the mode signals other than the mode 0 is relatively low compared to the mode 0 is that the detection error for the modes other than the mode 0 is relatively high . This point can be proved as follows.

를 위한 제로-포싱 등화기(zero-forcing equalizer)는

와 같이 표현되고, 제로-포싱 등화기의 출력 신호는 수학식 15와 같이 표현될 수 있다.When the received signal vector is expressed as Equation 9,

A zero-forcing equalizer for the < RTI ID = 0.0 >

And the output signal of the zero-forcing equalizer can be expressed as: < EMI ID = 15.0 >

로 표현되고, 모드 k 신호의 추정 오차는

로 표현될 수 있다. 모드 k 신호의 추정 오차의 분산(variance)은 수학식 16과 같이 표현될 수 있다.The estimated error vector for the transmitted signal is

, And the estimation error of the mode k signal is expressed by

. ≪ / RTI > The variance of the estimation error of the mode k signal can be expressed as: < EMI ID = 16.0 >

It can be seen from Equations (14) and (16) that the estimated error variance for mode signals other than mode 0 is significantly greater than the estimated error variance of mode 0 signal when the transmission / reception distance is large.

In the case of the UCA OAM scheme of the communication system 10 of FIG. 2, when the transmission / reception distance is much larger than the UCA radius, the decrease in the channel capacity shows a large variation in each mode as the transmission / reception distance increases. It becomes difficult to decode signals other than the mode 0 with a low error rate.

FIG. 5 schematically shows a communication system according to an embodiment, and FIG. 6 shows a concept of transmission of multimode signals through a spatial spreading scheme of the OAM transmitter shown in FIG.

5 and 6, the communication system 20 may include an OAM transmitter and an OAM receiver. For example, the communication system 20 may be an OAM transmission system. The communication system 20 may be a satellite communication system, a wireless backhaul network system, or a LoS communication system. The communication system 30A may be a Line-of-Sight (LoS) environment. Also, the communication system 20 may be a communication system of other LoS communication areas.

The structure and operation of each of the first UCA antenna 150 and the second UCA antenna 210 of FIG. 5 may be substantially the same as those of the transmission UCA antenna and the reception UCA antenna described in FIG.

It is assumed that the number of antenna elements included in each of the first UCA antenna 150 and the second UCA antenna 210 is N. [

The OAM transmitter 100 may generate and spread the multimode signals to all DFT beams so that the multimode signals are spatially spread between the DFT beams. The OAM transmitter 100 may transmit multimode signals spread to DFT beams to the OAM receiver 200.

The OAM transmitter 100 may include a spreading module 110, an OAM modulator 130 and a first UCA antenna 150.

는 송신하고자 하는 심볼들의 벡터를 의미하고,

는 스프레딩 모듈(110)에서 사용되는 스프레딩 행렬(spreading matrix)을 의미하고,

는 OAM 변조기(130)에서 사용되는 DFT 행렬을 의미할 수 있다.

Denotes a vector of symbols to be transmitted,

Denotes a spreading matrix used in the spreading module 110,

May refer to a DFT matrix used in the OAM modulator 130. [

Hereinafter, the concept of the spatial spreading scheme will be described with an example in which the number of antenna elements included in each of the first UCA antenna 150 and the second UCA antenna 210 is N = 4.

을 수학식 17을 통해 스프레딩 행렬

로 스프레딩할 수 있다.The spreading module 110 receives the multi-mode signals to be transmitted

To a spreading matrix < RTI ID = 0.0 >

.

을 DFT 빔들에 매핑(mapping)할 수 있다. 예를 들어, OAM 변조기(130)는 스프레딩된 신호들

을 DFT 행렬을 통해 변조할 수 있다.The OAM modulator 130 receives the output signal of the spreading module 110,

May be mapped to DFT beams. For example, the OAM modulator 130 may generate spreading signals

Can be modulated through a DFT matrix.

이 DFT 빔들 간의 공간적으로 스프레딩될 수 있다.As a result, the multimode signals to be transmitted

Can be spatially spread between the DFT beams.

The first UCA antenna 150 may transmit the modulated signals to the OAM receiver 200.

을 DFT 빔들에 1대1로 매핑(mapping)하여 송신하는 것과 달리, 본 발명에서는 송신하고자 하는 멀티모드 신호들

이 도 3b의 모든 DFT 빔들에 매핑(mapping)됨으로써 멀티모드 신호들이 DFT 빔들 간에 공간적으로 스프레딩되어 전송될 수 있다.That is, as shown in FIG. 3,

Is mapped to DFT beams on a one-to-one basis and transmitted. In contrast, in the present invention,

May be mapped to all the DFT beams in FIG. 3B so that the multimode signals may be spatially spread between the DFT beams.

Since the OAM transmitter 100 spreads each multimode signal among the DFT beams and transmits the same signal through all the DFT beams, all the mode signals experience the same channel, so that the mode capacity ) Can be maintained at the same level. In addition, this can increase the channel capacity of modes other than mode 0 through space spreading, and also increase the transmission / reception distance capable of decoding modes other than mode 0.

The OAM receiver 200 may demodulate the signals by dispreading the signals transmitted from the OAM transmitter 100.

OAM receiver 200 includes a second UCA antenna 210, an OAM demodulator 230, a channel equalizer 250, a dispreading module 270 and a detector 290. [ . ≪ / RTI >

는 OAM 복조기(230)에서 사용되는 DFT 행렬을 의미할 수 있다.

는 수학식 18과 같이 정의될 수 있다.

May refer to a DFT matrix used in the OAM demodulator 230. [

Can be defined as shown in Equation (18).

은 DFT 행렬을 포함하여 유니테리 행렬(unitary matrix) 특성을 갖는 것을 사용할 수 있다.Here, the spreading matrix

May have a unitary matrix characteristic including a DFT matrix.

Then, the signal vector received by the second UCA antenna 210, which is a reception UCA antenna at an arbitrary time, can be expressed as Equation (19).

Substituting Equation (6) into Equation (19), Equation (19) can be expressed again as Equation (20).

는 수학식 21과 같이 표현될 수 있다.here,

Can be expressed as: " (21) "

에 대한 최소 자승 추정치(Least-Squares Estimator(LSE))는 수학식 20을 통해 수학식 22와 같이 표현될 수 있다.

(Least-Squares Estimator (LSE)) with respect to Equation (20) can be expressed as Equation (22) through Equation (20).

는 아래 수학식 23과 같이 단순화될 수 있다.* Substituting Equation (21) into Equation (22)

Can be simplified as shown in Equation 23 below.

Equation (23) can be expressed again by equations (24) to (26).

OAM demodulator 230 may demodulate the received signals via Equation (24).

The channel equalizer 250 may perform a channel equalization operation through Equation 25

에 대한 추정치를 디스프레딩 행렬을 이용하여 획득(또는 계산)할 수 있다.The despreading module 270 may despread the output signals of the channel equalizer 250 through Equation (26). Accordingly, the despreading module 270 generates a transmission symbol

Can be obtained (or calculated) using a despreading matrix.

Substituting Equations (20) and (21) into Equation (22), Equation (22) can be expressed again as Equation (27).

와 같이 스프레딩 행렬

의 k-th 컬럼을

로 정의하면,

의 k-th 요소는 수학식 28과 같이 표현될 수 있다.

A spreading matrix

Of the k-th column

Lt; / RTI >

K-th < / RTI >

The mode capacity for mode k may be expressed as: < EMI ID = 29.0 >

는 수학식 30과 같이 표현될 수 있다.here,

Can be expressed by Equation (30).

Equation (29) can be expressed as Equation (31) again.

From equation (31), it can be seen that the mode capacity by the spatial spreading scheme is the same for all modes regardless of the mode index k.

FIG. 7 shows a far field pattern for each mode that occurs when a spatial spreading scheme according to an embodiment is applied to a UCA antenna having four elements.

The figure shows the propagation intensity of the waves reaching the receiving UCA antenna with a radius of 10λ at a distance of 100m from the far field pattern due to each mode signal when spreading by mode and then transmitting with DFT modulation.

만 송신되는 경우 수학식 19로부터 수신 신호는 수학식 32와 같이 표현될 수 있다.This means that the particular mode signal

The received signal can be expressed by Equation (32) from Equation (19).

는 수학식 33과 같이 표현될 수 있다.

Can be expressed by Equation (33).

That is, the propagation intensities of all the modes at the arbitrary receiving points can be made equal by the spatial spreading scheme. Therefore, even when the UCA OAM multi-mode signal is transmitted and received a long distance, modes other than the mode 0 can be received at an improved SNR.

FIG. 8 shows a result of simulating the SER performance of each mode for the conventional method and the spatial spreading method.

A computer simulation was performed to investigate the advantages of the space side spreading scheme of the present invention on the existing UCA OAM scheme. In the simulation, N _TX = N _RX = 4, R _TX = R _RX = 10λ, and transmission / reception distance D = 50m were applied.

8 shows a SER for each mode when four symbols encoded by 16-QAM are transmitted. In the conventional UCA OAM scheme, SER deviations are large in each mode, and in particular, the SER in the mode 3 is high, whereas the spatial spreading scheme shows that all modes exhibit the same SER performance.

FIG. 9 shows a result of simulating the integrated SER performance for all modes with respect to the existing UCA OAM scheme and spatial spreading scheme.

9 shows the SER performance for the sum of the four mode signals. In the case of QPSK encoding, spatial spreading scheme has SER lower than that of existing UCA OAM scheme when SNR is 12 dB or more, and space spreading scheme when SNR is 18 dB or more when 16-QAM is applied . In addition, it is recommended to use the spatial spreading method in a region where the SER is less than 0.1. In this example, the SNR gain is more than 3dB in the range of SER <0.01.

와

가 모두 N-by-N DFT matrix인 경우를 가정하였으나, N_TX와 N_RX가 같은 값이 아닌 경우에도 본 발명의 공간 스프레딩 기술을 적용하여 기존 UCA OAM 기술 대비 성능 개선을 달성할 수 있다.In describing the spatial spreading scheme described above, when both the number of transmitting UCA antenna elements and the number of receiving UCA antenna elements are N,

Wow

Is assumed to be an N-by-N DFT matrix. However, even when N _TX and N _RX are not equal to each other, the spatial spreading technique of the present invention can be applied to improve performance compared to the conventional UCA OAM technique.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field programmable gate array (FPGA) , A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing unit may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device , Or may be permanently or temporarily embodied in a transmitted signal wave. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

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

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI &gt; or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (10)

Spreading the multimode signals among the DFT beams by mapping each of the multimode signals to Discrete Fourier transform (DFT) beams; And
Modulating the spread multimode signals
/ RTI &gt;
The method according to claim 1,
Wherein the step of spreading comprises:
Spreading the multi-mode signals through a spreading matrix
/ RTI &gt;
The method according to claim 1,
Wherein the step of spreading comprises:
Calculating the multimode signals using the following equation: &lt; EMI ID = 34.0 &gt;
/ RTI &gt;
&Quot; (34) &quot;

here,

Quot; refers to the spread multi-mode signals,

Denotes a spreading matrix,

Means the multimode signals.
The method according to claim 1,
Wherein the modulating comprises:
Modulating the spread multi-mode signals using a DTF matrix
/ RTI &gt;
3. The method of claim 2,
Wherein the spreading matrix is a unitary matrix including a DFT matrix.
A spreading module for spreading the multimode signals among the DFT beams by mapping each of the multimode signals to Discrete Fourier transform (DFT) beams; And
Modulator for modulating spread multi-mode signals
And an Orbital Angular Momentum (OAM) transmitter.
The method according to claim 6,
The spreading module includes:
And an OAM transmitter for spreading the multi-mode signals through a spreading matrix.
The method according to claim 6,
The spreading module includes:
And calculates the spread multi-mode signals using the multi-mode signals: &lt; EMI ID = 35.0 &gt;
&Quot; (35) &quot;

here,

Quot; refers to the spread multi-mode signals,

Denotes a spreading matrix,

Means the multimode signals.
The method according to claim 6,
The modulator comprising:
And an OAM transmitter for modulating the spread multi-mode signals using a DTF matrix.
8. The method of claim 7,
Wherein the spreading matrix is a unitary matrix including a DFT matrix.

Images