KR102555056B1 - Closed-loop multi-antenna system and method for closed-loop multi-antenna communication security thereof - Google Patents

Abstract

The present invention relates to a closed-loop multi-antenna system and a closed-loop multi-antenna communication security method thereof, comprising: a modulator for generating a plurality of transmission signals by modulating data bits; a pre-distortion unit for pre-acquiring and sharing channel phase information, and pre-distorting the plurality of transmission signals using the pre-acquired channel phase information; a transmitter for wirelessly transmitting the plurality of pre-distorted transmission signals through multiple antennas; a receiver configured to obtain a received signal by receiving a signal transmitted wirelessly from a transmitting side; a distortion information calculating unit that receives and stores channel phase information in advance and calculates distortion information using the previously shared channel phase information; and a demodulation unit that removes the distortion of the received signal using the distortion information and then demodulates the received signal into original data bits.

Description

Closed-loop multi-antenna system and method for closed-loop multi-antenna communication security

The present invention relates to a new type of closed-loop multi-antenna system in which a signal is pre-distorted and transmitted using channel phase information in a multi-input multi-output (MIMO) system and a closed-loop multi-antenna communication security method thereof. .

The MIMO method for transmitting signals using multiple antennas is used to improve performance or transmission speed in a wireless LAN system or a mobile communication system after the 4th generation.

In the case of the MIMO method used for performance improvement, there is no difference in transmission rate compared to the transmission method using a single antenna, or the transmission rate may be lowered. It is a method of allocating and transmitting the value of the signal transmitted from each transmitter so that the final bit error rate (BER) performance can be improved. A representative example of this method is a space time block coding (STBC) method.

On the other hand, there is a multi-antenna transmission method that allows the transmission rate to increase by a factor of the number of transmission antennas by simultaneously transmitting different symbol values to multiple antennas to improve the amount of information transmitted for a certain period of time, that is, the transmission rate, rather than performance improvement. , this scheme is usually referred to as a spatial multiplexing (SM) scheme.

In addition, as communication between devices such as the Internet of Things has recently become active, security performance is also considered an important performance factor in addition to BER and capacity, which were considered performance measures in the conventional communication method, and in physical layer transmission technology Research on a physical layer security (PLS) technology to improve security performance is being conducted.

The present invention is a technology in which PLS is applied to a multi-antenna technology. In the model for the PLS technology to which an embodiment of the present invention is applied, a legitimate sender is generally referred to as Alice and a legitimate receiver as Bob, and illegal eavesdropping The character is called Eve. In the conventional method, by adding pseudo noise located in the null space of the channel gain between the legitimate transmitter and receiver, the legitimate receiver can automatically cancel the pseudo noise and acquire appropriate information. However, Eve, an illegal eavesdropper with a different channel environment, There has been a method of making it impossible to obtain information due to interference caused by similar noise.

However, this method has the disadvantage that additional energy is required to add pseudo noise, and the magnitude of the signal is not kept constant due to the addition of pseudo noise, which is a function of the channel gain. There is a disadvantage in that average power ratio (PAPR) increases, which may adversely affect transmission performance.

Domestic Patent Publication No. 10-2004-0089748 (published on October 21, 2004)

In order to solve the above problems, the present invention is to provide a new type of closed-loop multi-antenna system and its closed-loop multi-antenna communication security method that make it impossible for an eavesdropper to obtain illegal information without additional power consumption.

In addition, it is intended to provide a closed-loop multi-antenna system and its closed-loop multi-antenna communication security method that can reduce signal detection complexity as well as improve security and error performance by deriving a new STBC encoding matrix capable of providing a PLS function. .

The object of the present invention is not limited to the above-mentioned object, and other objects not mentioned will be clearly understood by those skilled in the art from the description below.

As a means for solving the above problems, according to an embodiment of the present invention, a modulator for generating a plurality of transmission signals by modulating data bits; a pre-distortion unit for pre-acquiring and sharing channel phase information, and pre-distorting the plurality of transmission signals using the pre-acquired channel phase information; a transmitter for wirelessly transmitting the plurality of pre-distorted transmission signals through multiple antennas; a receiver configured to obtain a received signal by receiving a signal transmitted wirelessly from a transmitting side; a distortion information calculating unit that receives and stores channel phase information in advance and calculates distortion information using the previously shared channel phase information; and a demodulation unit for removing the distortion of the received signal using the distortion information and then demodulating the received signal into original data bits.

로 변조한 후, 상기 T개의 복수 심볼로부터 T × N_T의 크기를 가지는 실수 신호용 직교 STBC(space time block coding) 부호화 행렬

을 구성하며, 상기 N_T는 송신 안테나 개수이고, 상기 T는 송신 안테나 개수 N_T에 따른 최소 심볼 주기 시간인 것을 특징으로 한다. When the multi-antenna transmission method is a space time block code (STBC) method having one receiving antenna, the modulator converts data bits into T complex symbols.

After modulation with , an orthogonal space time block coding (STBC) coding matrix for a real signal having a size of T × N _T from the T plurality of symbols

, wherein N _T is the number of transmit antennas, and T is the minimum symbol cycle time according to the number N _T of transmit antennas.

에 기반하여 채널 위상 왜곡 인자

를 계산한 후, 채널 위상 왜곡 인자

의 k번째 성분을 상기 실수 신호용 직교 STBC 행렬

의 k번째 열백터에 곱하여 채널 위상 왜곡된 직교 STBC 행렬을 생성하는 것을 특징으로 한다. The pre-distortion unit provides channel information

Channel phase distortion factor based on

After calculating the channel phase distortion factor

The kth component of is an orthogonal STBC matrix for the real signal

It is characterized by generating an orthogonal STBC matrix with channel phase distortion by multiplying by the k-th column vector of .

"의 식에 따라 생성되며, 상기

는 채널 위상 왜곡 인자이고, 상기

는 k번째 송신부에서 수신부에 이른 경로에 대한 복소 채널 이득이고, 상기

는

의 위상 정보인 것을 특징으로 한다. The channel phase distorted orthogonal STBC matrix is "

" is generated according to the formula of

is the channel phase distortion factor, and

Is the complex channel gain for a path from the k-th transmitter to the receiver,

Is

It is characterized in that the phase information of.

"로 표현되는 수신 신호를 획득 및 출력하며, 상기

는 채널 위상 왜곡된 직교 STBC 행렬이고, 상기

는

이고, 상기

는 실수행렬 형태의 정보 보안용 행렬이고, 상기

는

이고,

는 채널 잡음인 것을 특징으로 한다. The receiver "

Acquiring and outputting a received signal represented by ", wherein the

Is the channel phase distorted orthogonal STBC matrix, wherein

Is

and the above

Is a matrix for information security in the form of a real matrix,

Is

ego,

is the channel noise.

"의 식에 기반하여, T × N_T의 크기를 가지는 실수행렬 형태의 정보 보안용 행렬

를 계산하는 것을 특징으로 한다. The distortion information calculator "

Based on the expression of ", a matrix for information security in the form of a real matrix having a size of T × N _T

It is characterized by calculating .

"의 식에 따라 송신 심볼에 대한 추정 백터 값인

을 검출하는 것을 특징으로 한다. The demodulator "

"According to the expression of the estimated vector value for the transmitted symbol,

It is characterized by detecting.

로 변조하며, 상기 N_T는 송신 안테나 개수인 것을 특징으로 한다. When the multi-antenna transmission method is a Spatial Multiplexing (SM) method, the modulator converts data bits into N _T symbols.

It is modulated with , wherein N _T is the number of transmit antennas.

The predistortion unit obtains a channel matrix having a size of (N _R × N _T ) when the number of receiving antennas is N _R and the number of transmitting antennas is N _T , and all phase information of column vectors in the channel matrix is obtained. After calculating a channel phase distortion factor by using a channel phase distortion factor, the plurality of symbols are multiplied by the channel phase distortion factor to generate and output a channel phase distortion transmission signal.

"의 식에 따라 생성되며, 상기

는 "

"의 식에 따라 생성되는 채널 위상 왜곡 인자이고, 상기

는 k번째 송신부에서 i번째 수신부에 이른 경로에 대한 복소 채널 이득이고, 상기

는

의 위상 정보인 것을 특징으로 한다. The channel phase distorted transmission signal is "

" is generated according to the formula of

Is "

is a channel phase distortion factor generated according to the expression of

Is the complex channel gain for a path from the k-th transmitter to the i-th receiver,

Is

It is characterized in that the phase information of.

"로 표현되는 수신 신호를 획득 및 출력하며, 상기

는 (N_R × N_T)의 크기를 가지는 채널 행렬이고, 상기

은 (N_R × 1)의 크기를 가지는 열잡음 백터이고, 상기

는 정보 보안용 채널 행렬인 것을 특징으로 한다. The receiver "

Acquiring and outputting a received signal represented by ", wherein the

Is a channel matrix having a size of (N _R × N _T ), wherein

is a thermal noise vector having a size of (N _R × 1), and

is a channel matrix for information security.

"의 식에 따라 정보 보안용 채널 행렬을 계산하며, 상기

는 (N_R × 1)의 크기를 가지는 벡터로서, 채널 행렬

의 k번째 열 벡터인 것을 특징으로 한다. The distortion information calculator "

Calculate a channel matrix for information security according to the expression of

is a vector having a size of (N _R × 1), and the channel matrix

It is characterized in that the k-th column vector of .

"의 식에 따라 수신 신호의 왜곡을 모두 제거한 후, 복조하여 원래의 데이터 비트를 검출 및 출력하며, 상기

는 상기 정보 보안용 채널 행렬

으로부터 계산되는 신호검출 행렬로, 영점 강요 방식 사용시에는 "

"이고, 최소 평균 제곱 오차 방식 사용시에는 "

"인 것을 특징으로 한다.The demodulator "

After removing all distortion of the received signal according to the expression of ", demodulate to detect and output the original data bits,

Is the channel matrix for information security

As a signal detection matrix calculated from, when using the zero-force method, "

", and when using the least mean square error method, "

"It is characterized by

As a means for solving the above problem, according to another embodiment of the present invention, the transmitting side and the receiving side pre-sharing channel phase information; multi-transmitting through a plurality of transmission antennas after the transmission side pre-distorts a plurality of transmission signals using channel phase information; obtaining, at the receiving side, a received signal through a plurality of receiving antennas, and calculating a channel matrix for information security using the channel phase information; and detecting an original transmission signal after removing distortion of the received signal using the channel matrix for information security.

According to the present invention, the multi-antenna system of the present invention pre-distorts the transmission signal using the channel phase information previously shared by the transmitting side and the receiving side, so that an eavesdropper can block illegal information acquisition without additional power consumption. let it be

In addition, when the multi-antenna transmission method is the STBC method, the symbol encoding matrix of the transmitter is derived so that the receiver can configure the channel matrix necessary for signal detection by mistake, thereby improving security performance and error performance, as well as reducing signal detection complexity. do.

1 illustrates a closed-loop multi-antenna system for enhancing security functions according to an embodiment of the present invention.
2 is a diagram for explaining a closed-loop multi-antenna communication security method of the STBC method according to an embodiment of the present invention.
3 is a diagram for explaining a closed-loop multi-antenna communication security method of SM scheme according to another embodiment of the present invention.

The following merely illustrates the principles of the present invention. Therefore, those skilled in the art can invent various devices that embody the principles of the present invention and fall within the concept and scope of the present invention, even though not explicitly described or shown herein. In addition, it is to be understood that all conditional terms and embodiments listed herein are, in principle, expressly intended only for the purpose of making the concept of the present invention understood, and not limited to such specifically listed embodiments and conditions. It should be.

Further, it should be understood that all detailed descriptions reciting specific embodiments, as well as principles, aspects and embodiments of the present invention, are intended to encompass structural and functional equivalents of these matters. In addition, it should be understood that such equivalents include not only currently known equivalents but also equivalents developed in the future, that is, all devices invented to perform the same function regardless of structure.

Thus, for example, the block diagrams herein are to be understood as representing conceptual views of exemplary circuits embodying the principles of the present invention. Similarly, all flowcharts, state transition diagrams, pseudo code, etc., are meant to be tangibly represented on computer readable media and represent various processes performed by a computer or processor, whether or not the computer or processor is explicitly depicted. It should be.

1 illustrates a closed-loop multi-antenna system for enhancing security functions according to an embodiment of the present invention.

Referring to FIG. 1, the system of the present invention is composed of a legitimate transmitter 110 and a legitimate receiver 120 that pre-share channel phase information of a transmitter according to a closed loop transmission technique, and the legitimate transmitter 110 is a modulator. 112, a pre-distortion unit 114, and a transmission unit 116, and the legitimate receiving end 120 may include a receiving unit 122, a distortion information calculation unit 124, a demodulation unit 126, and the like. there is.

The modulator 112 of the legal transmitter 110 modulates data bits to be transmitted into a plurality of transmission signals.

The pre-distortion unit 114 pre-acquires and stores channel phase information of the transmission side, and uses this to pre-distort a plurality of transmission signals and transmits them to the transmission unit.

The transmission unit 116 includes a plurality of antennas and wirelessly multiplexes and outputs a plurality of pre-distorted transmission signals through the plurality of antennas. Then, a channel gain according to the transmission path is added to the transmission signal and noise is added thereto, and then the signal reaches the legitimate receiving end 120.

The receiving unit 122 of the legitimate receiving end 120 also includes a plurality of antennas, through which the transmitting side receives a plurality of transmission signals wirelessly transmitted.

The distortion information calculation unit 124 receives and stores channel phase information from the legal transmitter 110 in advance, and calculates distortion information for removing all distortion included in the received signal based on this.

The demodulator 126 removes all distortion of the received signal using the distortion information, demodulates it, and detects and outputs original data bits.

That is, in the present invention, in a communication system using closed-loop multiple antennas, considering that a legal transmitter and a legal receiver share channel phase information in advance, the transmission signal is pre-distorted using the channel phase information and then transmitted. Ensure that only legitimate recipients can receive and process them.

Continuously, with reference to FIGS. 2 and 3 , the closed-loop multi-antenna communication security method according to the STBC scheme and the SM will be described in more detail. In addition, below, for convenience of explanation, scalar variable values are written in italic lowercase letters, vectors composed of several scalar values are written in bold lowercase letters, and matrices are written in bold uppercase letters.

FIG. 2 is a diagram for explaining a closed-loop multi-antenna communication security method of an STBC scheme with one receiver according to an embodiment of the present invention.

로 변조하고, 변조된 T개의 복소 심볼로부터 N_T개의 송신 안테나로 T시간 동안 전송하기 위한 실수 신호용 직교 부호화 행렬

을 구성한다. 이때, 실수 신호용 직교 STBC 행렬은 실수 값으로 구성되는 경우에 직교 행렬이 될 수 있는 행렬을 의미하며, 본 발명에 사용되는 심볼 값들은 복소 변조 심볼로 구성된다.In step S11, the modulator 112 converts data bits into T complex symbols.

An orthogonal coding matrix for a real signal to be modulated with , and transmitted from the modulated T complex symbols to N _T transmit antennas for T time

make up In this case, an orthogonal STBC matrix for a real signal means a matrix that can become an orthogonal matrix when composed of real values, and symbol values used in the present invention are composed of complex modulation symbols.

는 (T × 1)의 크기를 가지는

의 열벡터이며,

행렬의 각 열백터,

들은

값들을 부호화한 값들로 구성된다. In this case, N _T is the number of transmit antennas, T is the minimum symbol cycle time according to the number of transmit antennas N _T ,

has a size of (T × 1)

is a column vector of

each column vector of the matrix,

heard

It consists of values that have encoded values.

는 수학식 1과 같이 구성될 수 있다. For example, when the number of transmit antennas N _T is 4, an orthogonal STBC matrix for a real signal

may be configured as in Equation 1.

[Equation 1]

For reference, when T = N _T , the method for obtaining the maximum transmission efficiency is called a full rate method (ie, a method in which the coding rate is 1). In the method according to the present invention, the BER performance of It enables the implementation of a full-rate scheme with T = N _T without degradation.

에 기반하여 채널 위상 왜곡 인자

를 계산한다. 이때,

는 k번째 송신부에서 수신부에 이른 경로에 대한 복소 채널 이득이고,

는

의 위상 정보이다.In step S12, the pre-distortion unit 114 obtains channel information of the transmission unit 116 in advance.

Channel phase distortion factor based on

Calculate At this time,

Is the complex channel gain for the path from the kth transmitter to the receiver,

Is

is the phase information of

의 k번째 성분을 실수 신호용 직교 STBC 행렬

의 k번째 열백터에 곱하는 방식으로 채널 위상 왜곡된 직교 STBC 행렬

을 수학식 2와 같이 산출한다. 그리고 채널 위상 왜곡된 직교 STBC 행렬

를 안테나 및 시간별 전송 신호로서 할당한 후, 송신부(116)의 다중 안테나를 통해 무선 송신하도록 한다. In step S13, the pre-distortion unit 114 is a channel phase distortion vector

The kth component of is an orthogonal STBC matrix for real signals

The channel phase distorted orthogonal STBC matrix by multiplying the kth column vector of

is calculated as in Equation 2. and the channel phase distorted orthogonal STBC matrix

After allocating as a transmission signal for each antenna and time, it is wirelessly transmitted through multiple antennas of the transmitter 116.

[Equation 2]

를 획득한다. In step S14, the receiver 122 of the legitimate receiver 120 receives the signal transmitted during the T symbol period time, and as shown in Equation 3 (T × 1) ten vector received signals

Acquire

[Equation 3]

은 (T × 1)의 크기를 가지는 열잡음 백터이다.At this time,

Silver (T × 1) is a thermal noise vector.

가 전송되는 경우, k번째 열벡터

에 채널 이득

가 인가되어 채널 왜곡 인자

는 무효화되게 된다. 이에 수학식 3의

의 k번째 열백터는

가 되며, 그 결과 수학식 3은 수학식 4로 다시 표현될 수 있다. Phase-distorted orthogonal STBC matrix of the present invention

is transmitted, the kth column vector

on channel gain

is applied and the channel distortion factor

will be invalidated. Accordingly, Equation 3

The kth column vector of

, and as a result, Equation 3 can be re-expressed as Equation 4.

[Equation 4]

는

이고,

는

이고,

는 채널 잡음 백터이며,

는

와

가 같도록 만드는 실수행렬 형태의 정보 보안용 행렬로

는 "

"이 되도록 하는 관계식에 기반하여 다음 단계 S15에서 계산된다. At this time,

Is

ego,

Is

ego,

is the channel noise vector,

Is

and

A matrix for information security in the form of a real matrix that makes

Is "

is calculated in the next step S15 based on the relational expression that makes

에 기반하여, T × N_T의 크기를 가지는 실수행렬 형태의 정보 보안용 행렬

를 "

"로부터 계산한다. In step S15, the distortion information calculation unit 124 transmits the pre-shared channel phase information of the transmission unit 116.

Based on , a matrix for information security in the form of a real matrix having a size of T × N _T

cast "

"calculated from

는 이하의 수학식 5와 같이 유도될 수 있다.For example, as in Equation 1, when the number of transmit antennas N _T is 4, a channel matrix for information security

Can be derived as in Equation 5 below.

[Equation 5]

을 적용하여 수신 신호에 포함된 왜곡을 모두 제거한 후, 이를 복조하여 원래의 데이터 비트를 획득하도록 한다. In the last step S16, the demodulation unit 126 adds a matrix for information security to the received signal.

After removing all distortion included in the received signal by applying , the original data bits are obtained by demodulation.

는 수학식 5와 같이 실수로만 이루어진 행렬이기 때문에, 기존의 복소행렬에 대한 복잡한 연산 대신에 수학식 6에서와 같이 간단한 행렬 전치연산을 이용하여 T 시간 동안의 송신 심볼에 대한 추정 백터 값인

을 검출할 수 있다. Channel matrix for information security of the present invention

Since is a matrix made up of only real numbers as shown in Equation 5, a simple matrix transposition operation is used as in Equation 6 instead of a complicated operation on the conventional complex matrix, so that the estimated vector value for the transmitted symbol for time T

can be detected.

[Equation 6]

를 이용하여 신호를 왜곡하였기 때문에 가능하다. 이에 합법적 송수신자간의 채널 위상 정보를 알지 못하는 도청자는 이러한 무효화를 수행할 수 없으며, 적절한 신호 검출 방법을 사용하더라도 원래의 정보를 복원할 수 없게 된다. The pre-distortion cancellation according to the method of FIG. 2 is the channel phase information between legitimate transmitter and receiver.

This is possible because the signal was distorted using Accordingly, an eavesdropper who does not know the channel phase information between legitimate transmitter and receiver cannot perform such invalidation, and cannot restore original information even if an appropriate signal detection method is used.

3 is a diagram for explaining a closed-loop multi-antenna communication security method of SM scheme according to another embodiment of the present invention.

로 변조한다. 이때, N_T는 송신 안테나 개수이고, 상기

는 상기 N_T개의 안테나를 통하여 N_T개의 심볼이 동시에 병렬 전송되는 것을 의미한다. 그리고

는 행렬의 "전치(transpose)" 연산으로,

는 행백터이므로

는 열백터가 됨을 의미한다. In step S21, the modulator 112 converts the data bits into N _T symbols.

modulate with In this case, N _T is the number of transmit antennas, and the

means that N _T symbols are simultaneously transmitted in parallel through the N _T antennas. and

is the "transpose" operation of a matrix,

is a row vector, so

means that is a ten vector.

이고, 합법적 수신자의 N_R개의 수신부에서 수신되는 신호 백터

일 때, 수신 신호는 이하의 수학식 7로 표현될 수 있다.The signal vector of the legitimate sender transmitted on N _T antennas using the SM scheme

, and the signal vector received at N _R receivers of legitimate receivers

When , the received signal may be expressed by Equation 7 below.

[Equation 7]

는 (N_R × N_T)의 크기를 가지는 채널 행렬이고,

은 (N_R × 1)의 크기를 가지는 열잡음 백터이다. At this time,

Is a channel matrix having a size of (N _R × N _T ),

is a thermal noise vector of size (N _R × 1).

을 구한다. In step S22, the predistortion unit 114 configures the number of receive antennas of the receiver as N _R and the number of transmit antennas as N _T , and the size of (N _R × N _T ) for the SM method according to Equation 8 below. Channel matrix with

save

[Equation 8]

는 k번째 송신부에서 i번째 수신부에 이른 경로에 대한 복소 채널 이득을 의미한다. At this time,

denotes a complex channel gain for a path from the k-th transmitter to the i-th receiver.

는 채널 행렬

의 k번째 열공간을 통하여 전송됨을 고려하여, 해당 열벡터의 위상 정보를 모두 이용하여 전송 신호에 대한 채널 위상 왜곡 인자

를 계산한다. And the signal transmitted from the k-th transmit antenna in the SM scheme

is the channel matrix

Considering that it is transmitted through the k-th column space of , the channel phase distortion factor for the transmission signal using all the phase information of the corresponding column vector

Calculate

[Equation 9]

는

의 위상 정보를 의미한다. At this time,

Is

means the phase information of

를 k번째 안테나로 전송될 심볼

에 곱하여 채널 위상 왜곡된 전송 신호 백터

를 수학식 10과 같이 생성한 후, 송신부(116)의 안테나 별로 할당하여 채널로 송신하도록 한다. In step S23, the pre-distortion unit 114 is the k-th channel phase distortion factor calculated through step S22.

Symbol to be transmitted to the k-th antenna

Transmit signal vector with channel phase distortion multiplied by

After generating as shown in Equation 10, it is assigned to each antenna of the transmitter 116 and transmitted through a channel.

[Equation 10]

를 획득한다. In step S24, the receiver 122 of the legitimate receiver 120 receives the signal transmitted during one symbol period, and the received signal expressed as Equation 11

Acquire

[Equation 11]

와 이에 상응하는 채널 위상 왜곡 인자

_, 에 기반하여 정보 보안용 채널 행렬

를 계산한다. In step S25, the distortion information calculation unit 124 transmits the pre-shared channel matrix of the transmission unit 116.

and the corresponding channel phase distortion factor

_, channel matrix for information security based on

Calculate

[Equation 12]

는 (N_R × 1)의 크기를 가지는 백터로서, 채널 행렬

의 k번째 열 벡터이다. At this time,

is a vector with a size of (N _R × 1), and the channel matrix

is the kth column vector of

의 i번째 원소

는 열벡터

의 모든 원소 N_R개에 대한 위상 정보를 담고 있는 사전 왜곡 인자

와 곱해짐으로써 채널 위상 정보

를 무효화시킬 수 있지만, 사전 왜곡 인자

전체가 무효화되는 것은 아니며, 정보 보안용 채널 행렬

의 k번째 열벡터

의 i번째 원소는 크기성분

와 N_R - 1개의 위상 정보를 가지고 있는 복소수이다.

the i element of

is a column vector

A predistortion factor containing phase information for all N _R elements of

Channel phase information by being multiplied with

can be negated, but the predistortion factor

The channel matrix for information security is not invalidated in its entirety.

the kth column vector of

The i-th element of is the magnitude component

and N _R - is a complex number with one phase information.

에 기반하여 신호 검출 행렬

을 구성한 후, 이를 통해 수신 신호에 포함된 왜곡을 모두 제거한 후 복조하여 원래의 데이터 비트를 검출 및 출력하도록 한다. In step S26, the demodulation unit 126 is a matrix for information security

Signal detection matrix based on

After configuring, through this, all distortion included in the received signal is removed, and then demodulated to detect and output original data bits.

는 수학식 13에 따라 획득될 수 있다. Estimated signal vector for signal vector with distortion information removed

Can be obtained according to Equation 13.

[Equation 13]

는 정보 보안용 채널 행렬

으로부터 계산되는 신호검출 행렬로써, 정보 보안용 채널 행렬

를 이용하여 기존의 신호검출 방식과 동일하게 계산할 수 있다. 예를 들어, 영점 강요(zero forcing; ZF) 방식을 사용할 경우에는

일 수 있으며, 최소 평균 제곱 오차(minimum mean square error; MMSE) 방식을 사용할 경우에는

일 수 있다. At this time,

is the channel matrix for information security

As a signal detection matrix calculated from, a channel matrix for information security

It can be calculated in the same way as the conventional signal detection method using For example, when using the zero forcing (ZF) method,

, and when using the minimum mean square error (MMSE) method,

can be

The pre-distortion invalidation according to the method of FIG. 3 is also possible because the signal is distorted using the channel information between the legitimate sender and the receiver, and since the eavesdropper does not know such channel information, the invalidation cannot be performed, and an appropriate signal detection method can be used. Even if it is used, the signal cannot be decoded.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific embodiments described above, and is common in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims. Of course, various modifications and implementations are possible by those with knowledge of, and these modifications should not be individually understood from the technical spirit or perspective of the present invention.

Claims (14)

a modulator for generating a plurality of transmission signals by modulating data bits;
a pre-distortion unit for pre-acquiring and sharing channel phase information, and pre-distorting the plurality of transmission signals using the pre-acquired channel phase information;
a transmitter for wirelessly transmitting the plurality of pre-distorted transmission signals through multiple antennas;
a receiver configured to obtain a received signal by receiving a signal transmitted wirelessly from a transmitting side;
a distortion information calculating unit that receives and stores channel phase information in advance and calculates distortion information using the previously shared channel phase information; and
And a demodulation unit for removing the distortion of the received signal using the distortion information and then demodulating the received signal into original data bits.
the modulation unit
If the multi-antenna transmission method is the STBC (Space Time Block Code) method with one receiving antenna, the data bits are T complex symbols.

After modulation with , an orthogonal space time block coding (STBC) coding matrix for a real signal having a size of T × N _T from the T plurality of symbols

wherein N _T is the number of transmit antennas, and T is the minimum symbol cycle time according to the number of transmit antennas N _T . delete The method of claim 1, wherein the pre-distortion unit
channel information

Channel phase distortion factor based on

After calculating the channel phase distortion factor

The kth component of is an orthogonal STBC matrix for the real signal

A closed-loop multi-antenna system for enhancing security functions, characterized by generating an orthogonal STBC matrix with channel phase distortion by multiplying by the k-th column vector of . The method of claim 3, wherein the channel phase distorted orthogonal STBC matrix is
"

" is generated according to the formula of

is the channel phase distortion factor, and

Is the complex channel gain for a path from the k-th transmitter to the receiver,

Is

Closed-loop multi-antenna system for enhancing security function, characterized in that the phase information of. The method of claim 4, wherein the receiving unit
"

Acquiring and outputting a received signal represented by ", wherein the

Is the channel phase distorted orthogonal STBC matrix, wherein

Is

and the above

Is a matrix for information security in the form of a real matrix,

Is

ego,

Wherein is channel noise, a closed-loop multi-antenna system for enhancing security functions. The method of claim 5, wherein the distortion information calculator
"

Based on the expression of ", a matrix for information security in the form of a real matrix having a size of T × N _T

Closed-loop multi-antenna system for enhancing security function, characterized in that for calculating The method of claim 6, wherein the demodulation unit
"

"According to the expression of the estimated vector value for the transmitted symbol,

Closed loop multi-antenna system for enhancing security function, characterized in that for detecting. The method of claim 1, wherein the modulation unit
If the multi-antenna transmission method is SM (Spatial Multiplexing), data bits are N _T symbols

Modulated with , wherein N _T is the number of transmit antennas. The method of claim 8, wherein the pre-distortion unit
When the number of receiving antennas is N _R and the number of transmitting antennas is N _T , a channel matrix having a size of (N _R × N _T ) is obtained, and the channel phase is obtained by using all phase information of column vectors in the channel matrix. After calculating the distortion factor, the channel phase distortion factor is multiplied by the plurality of symbols to generate and output a channel phase distorted transmission signal. 10. The method of claim 9, wherein the channel phase distorted transmission signal
"

" is generated according to the formula of

Is "

is a channel phase distortion factor generated according to the expression of

Is the complex channel gain for a path from the k-th transmitter to the i-th receiver,

Is

Closed-loop multi-antenna system for enhancing security function, characterized in that the phase information of. 11. The method of claim 10, wherein the receiving unit
"

Acquiring and outputting a received signal represented by ", wherein the

Is a channel matrix having a size of (N _R × N _T ), wherein

is a thermal noise vector having a size of (N _R × 1), and

Is a channel matrix for information security. A closed-loop multi-antenna system for enhancing security functions. The method of claim 11, wherein the distortion information calculator
"

Calculate a channel matrix for information security according to the expression of

is a vector having a size of (N _R × 1), and the channel matrix

A closed-loop multi-antenna system for enhancing security functions, characterized in that the k-th column vector of 12. The method of claim 11, wherein the demodulation unit
"

After removing all distortion of the received signal according to the expression of ", demodulate to detect and output the original data bits,
remind

Is the channel matrix for information security

As a signal detection matrix calculated from, when using the zero-force method, "

", and when using the least mean square error method, "

"A closed-loop multi-antenna system for enhancing security functions, characterized in that. pre-sharing channel phase information between the transmitting side and the receiving side;
multi-transmitting through a plurality of transmission antennas after the transmission side pre-distorts a plurality of transmission signals using channel phase information;
obtaining, at the receiving side, a received signal through a plurality of receiving antennas, and calculating a channel matrix for information security using the channel phase information; and
After removing distortion of the received signal using the channel matrix for information security, detecting an original transmitted signal;
The step of multiplexing through the plurality of transmit antennas
If the multi-antenna transmission method is the STBC (Space Time Block Code) method with one receiving antenna, the data bits are T complex symbols.

After modulation with , an orthogonal space time block coding (STBC) coding matrix for a real signal having a size of T × N _T from the T plurality of symbols

wherein N _T is the number of transmit antennas, and T is the minimum symbol cycle time according to the number of transmit antennas N _T .

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