KR20120086497A - Apparatus and method for transmitting secrecy data on a number of transmission channels in a multi-channel communication system - Google Patents

Abstract

PURPOSE: A security data transmission apparatus, method thereof, and multi-channel wireless communication system are provided to transmit data by maximizing security transmission rates in a multi-channel wireless communication environment. CONSTITUTION: A transmission apparatus differentiates CSI(Channel State Information) access levels from multiple channels(300). The transmission apparatus maximizes security capacity(310). The transmission apparatus allocates the transmission power of the multiple channels in order to maximize security transmission rates under maximized security capacity conditions(320). The transmission apparatus executes the beam-forming of a data signal according to transmission power assignment results(330).

Description

Apparatus and method for transmitting secrecy data on a number of transmission channels in a multi-channel communication system}

One aspect of the present invention relates to a wireless communication technology, and more particularly, to a power control and secure data transmission technology for optimizing a secure transmission rate in a multi-channel wireless communication environment.

Wireless communication uses an open medium called air in a manner of transmitting a signal to air or receiving a signal in air to perform communication. Therefore, if an unauthorized third party is located in close proximity to the receiver and knows how to encode the signal transmitted to the receiver, there is a risk of eavesdropping on the transmitted signal to easily extract confidential information between the receiver and the sender.

In the course of the communication between the sender and the receiver, a communication model was first proposed by Weiner in which unauthorized third parties intercepted data transmitted and received between the sender and the receiver. Since then, methods for increasing the secure transmission rate in wireless communication have been studied due to the broadcasting characteristics of wireless communication.

According to an aspect, a power control and secure data transmission technique for optimizing a secure transmission rate in a multi-channel wireless communication environment is proposed.

According to an aspect of the present invention, a method for transmitting a data securely through multiple channels may include differentiating the degree of access to channel state information for multiple channels according to whether the user taps to maximize security capacity, and secured under the maximum security capacity conditions. Allocating on-off the transmission power of the multi-channel so as to maximize the transmission rate, and beamforming the data signal according to the transmission power allocation result.

According to another aspect, a multichannel wireless communication system includes a multiple input single output multiple eavesdropping device (MISOME), a receiving device having a single receiving antenna, and a plurality of transmitting antennas to maximize the secure transmission rate in the presence of a fading eavesdropping channel of MISOME. And a transmission apparatus for allocating transmission power of the channel on-off and beamforming a secure data signal to the reception apparatus according to the allocation result.

According to another aspect of the present invention, a security data transmission apparatus includes a security capacity setting unit for maximizing security capacity by differentiating the degree of access to channel state information for multiple channels, and multiple security to maximize security transmission rate under the maximum security capacity condition. And a power setting unit for allocating the transmission power of the channel on-off and a transmission unit for beamforming the data signal according to the transmission power allocation result.

According to an embodiment, in a multi-channel wireless communication environment, data may be transmitted by maximizing a secure transmission rate. That is, the transmission power of the transmission channel is allocated on-off in the presence of the fading eavesdropping channel of the multi-input multiple-output multiple eavesdropping device (MISOME), and the secure data rate is maximized by beamforming the secure data signal to the receiving device according to the allocation result. .

1 is a block diagram showing a multi-channel wireless communication system according to an embodiment of the present invention,
2 is a detailed configuration diagram of a transmitter according to an embodiment of the present invention;
3 is a flowchart illustrating a data transmission method of a transmission apparatus according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the terms described below are defined in consideration of the functions of the present invention, and this may vary depending on the intention of the user, the operator, or the like. Therefore, the definition should be based on the contents throughout this specification.

1 is a block diagram showing a multi-channel wireless communication system 1 according to an embodiment of the present invention.

Referring to FIG. 1, the multi-channel wireless communication system 1 of the present invention includes a transmitter 10, a receiver 12, and an eavesdropping device 14.

The transmitter 10 includes a transmission antenna 100, and transmits a data signal to a receiver 12 through a wireless channel using the transmission antenna 100. The transmitted data signal is reflected by the interference object existing between the transmitter 10 and the receiver 12 and faded in different paths and received by the receiving antenna 120.

The receiving device 12 receives data signals fading in different paths using the receiving antenna 120. On the other hand, the eavesdropper 14 located in the data signal transmission range of the transmitter 10 taps the data signal transmitted from the transmitter 10 using the tapping antenna 140.

Looking at the eavesdropping communication model in more detail, the transmitter 10 transmits a data signal to the receiver 12 through a legal channel. The receiver 12 receives a data signal through a legal channel. On the other hand, the data signal received by the receiving device 12 is intercepted by the eavesdropping device 14 which is not allowed through the eavesdropper channel.

One of the user's most important concerns in wireless communication is to prevent unauthorized eavesdropping devices 14 from intercepting data transmitted and received between the transmitting device 10 and the receiving device 12. Therefore, in the legal channel and the eavesdropping channel each having a predetermined channel capacity, the receiver 12 is interested in a condition in which the data signal can be received without being intercepted by the eavesdropping device 14.

The channel capacity refers to the maximum data rate at which data is transmitted to the other party through the channel without error, that is, the information transmission capacity that the transmission medium used can accommodate. By security capacity is meant the maximum data rate at which data is transmitted to the authorized receiver 12 over the legal channel without eavesdropping on the eavesdropping device 14. That is, the security capacity is calculated as the ratio of the channel capacity of the legal channel to the channel capacity of the eavesdropping channel.

According to one embodiment, in the multi-channel wireless communication system 1 of the present invention, as shown in FIG. 1, the transmitting apparatus 10 has a plurality of transmitting antennas n ₁ , n ₂ ,..., N _t . The receiving device 12 has a single receiving antenna n _r . The wiretap device 14 is a multiple-input single-output multiple-eavesdropper (hereinafter referred to as MISOME) that follows a multiple input multiple output scheme. Hereinafter, the tapping device 14 is used in combination with MISOME.

2 is a detailed configuration diagram of a transmitter 10 according to an embodiment of the present invention.

1 and 2, the transmission apparatus 10 includes a security capacity setting unit 200, a power setting unit 210, and a transmitter 220 to optimize transmission power allocation of a channel and maximize a secure transmission rate. .

The security capacity setting unit 200 maximizes the security capacity by differentiating the degree of access to the channel state information for the multiple channels according to the eavesdropping. Multiple channels include legitimate channels and eavesdropper channels. The transmitter 10 has access to full channel state information (full CSI) through a legal channel, and partial channel state information (partial) through an eavesdropping channel. channel state information: partial CSI). The channel state information describes the characteristics of the channel. It is assumed that the transmitting device 10 knows the position of the tapping device 14. The access right to the CSI of the transmitter 10 may be determined according to an average received signal-to-noise ratio (SNR).

Based on the location-aware scenario described above, the present invention proposes an optimal power allocation strategy that can maximize the achievable secrecy rate with perfect secrecy.

Specifically, the power setting unit 210 allocates the transmit power of the channel on-off to maximize the attainable secure transmission rate under the Rayleigh-fading wiretap channels of MISOME. The transmitter 200 beamforms a security data signal to the receiver 12 according to the allocation result of the power setting unit 210.

The power setting unit 210 may allocate the transmission power based on the numbers of antennas and the average received SNRs. For example, if the size of the channel gain parameter is greater than or equal to a predetermined threshold, the transmission power parameter is allocated to 1, and if the channel gain parameter is smaller than the threshold, the transmission power parameter is assigned to 0. At this time, the threshold value is set by using the number of antennas of the transmitter 10, the number of antennas of the eavesdropping device 14, the signal-to-noise ratio of the receiver 12, and the signal-to-noise ratio of the eavesdropping device 14.

With reference to the following equations, an optimal power allocation strategy that can maximize the achievable secrecy rate will be described.

First, in the present invention, a transmitter 10 having n _t antennas 100 is legal in the presence of the tapping device 14 that taps a signal with n _e antennas 140 through a MISOME wiretap channel. It is assumed that security data is transmitted to the receiver 12 having a single antenna 120. In this case, the signals received by the receiver 12 and the tapping device 14 are as shown in Equations 1 and 2, respectively.

은

이 전력 제한 tr(Σ)≤1 을 만족하는 공분산 행렬(covariance matrix)을 따른다. tr(?)은 트레이스 연산자(trace operator)이다.

은 합법 채널의 레일리 페이딩 채널 이득 파라미터(Rayleigh-fading channel gains)이다.

는 수신장치(12)가 수신한 신호에 첨가된 잡음신호(additive white Gaussian noises)이다. snr_r은 수신장치(12)에 대한 평균 신호 대 잡음비(the average received signal-to-noise ratios(SNRs) per antenna at the receiver)를, n_t는 송신장치(10)의 송신 안테나 수를 나타낸다.In Equation 1, y _r represents a signal that the receiver 12 receives through the legal channel.

silver

The covariance matrix satisfies this power limit tr (Σ) ≦ 1. tr (?) is a trace operator.

Is the Rayleigh-fading channel gains of the legal channel.

Denotes additive white Gaussian noises added to the signal received by the receiver 12. snr _r denotes the average received signal-to-noise ratios (SNRs) per antenna at the receiver, and n _t denotes the number of transmit antennas of the transmitter 10.

은

이 전력 제한 tr (Σ)≤1 을 만족하는 공분산 행렬(covariance matrix)을 따른다. tr (?)은 트레이스 연산자(trace operator)이다.

은 도청 채널의 레일리 페이딩 채널 이득 파라미터(Rayleigh-fading channel gains)이다.

는 도청장치(14)가 수신한 신호에 첨가된 잡음신호(additive white Gaussian noises)이다. snr_e은 도청장치(14)에 대한 평균 신호 대 잡음비(the average received signal-to-noise ratios(SNRs) per antenna at the eavesdropper)를, n_t는 송신장치(10)의 송신 안테나 수를 나타낸다.In Equation 2, y _e represents a signal that the eavesdropping device 14 receives on the eavesdropping channel.

silver

The covariance matrix satisfies this power limit tr (Σ) ≦ 1 . tr (?) is a trace operator.

Is the Rayleigh-fading channel gains of the eavesdropping channel.

Is the additive white Gaussian noises added to the signal received by the eavesdropping device 14. snr _e denotes the average received signal-to-noise ratios (SNRs) per antenna at the eavesdropper for the eavesdropping device 14, and n _t denotes the number of transmit antennas of the transmitting device 10.

Assuming the transmitter 10 has access to perfect CSI for the receiver 12, the instantaneous perfect secrecy capacity (nat / s / Hz) under the MISOME eavesdropping channel ) Is the same as Equation 3.

는 켤레전치(conjugate transpose)를, I는 단위 행렬(identity matrix)을,

는 행렬 A(matrix A)가 양의 준정부호 행렬(positive semidefinite)임을 각각 나타낸다.Superscript

Is the conjugate transpose, I is the identity matrix,

Denotes that matrix A is a positive semidefinite matrix.

In Equation 3, in order to optimize the input covariance for secrecy capacity maximization, the transmitting apparatus 10 uses all channels for both a legal channel and an eavesdropper channel. Full CSI access is required, but this is not practical.

In order to solve the above-described problem, the present invention provides that the transmitter 10 has access to the full channel state information (full CSI) for the legal channel, and partial channel state information (partial) based on location recognition for the eavesdropping channel. Assume that you have access to CSI). Under the above assumption, the security capacity C _s is given by Equation 4.

이다.

이면, 식 5 및 식 6과 같다.

는 평균값 λ을 갖는 n차 Erlang 분포이다.In equation 4

to be.

If it is, it is the same as Formula 5 and Formula 6.

Is an n-th order Erlang distribution with an average value λ.

의 방향으로 데이터 신호를 빔포밍하는 경우(예:rank-one Σ with a nonzero eigenvector

)이고, 식 6은 어느 방향(any direction)으로 데이터 신호를 빔포밍하는 경우(예:any rank-one Σ)이다. 따라서 최대의 달성가능 보안 전송률(achievable secrecy rate)

은 식 7과 같다.Equation 5 is

Beamforming the data signal in the direction of (e.g., rank-one Σ with a nonzero eigenvector

(6) is a case of beamforming the data signal in any direction (for example, any rank-one?). Thus maximum achievable secrecy rate

Is the same as Equation 7.

인 조건에서 보안 전송률(secrecy rate)

을 최대화할 수 있는 최적의 λ인

는 식 8과 같다. The present invention proposes an optimal power allocation scheme as shown in Equation 8 that can maximize the attainable secure transmission rate in Equation 7. In addition, the optimal power allocation scheme allows for an ergodic secrecy rate under the MISOME secure channel.

Secure rate under secure conditions

Is the optimal λ to maximize

Is the same as Equation 8.

는 식 9와 같이 기설정된 문턱값(threshold)

에 따른 온-오프(on-off) 전력 할당 값이다.Then, the best

Is a predetermined threshold as shown in Equation 9.

Is an on-off power allocation value.

가 기설정된 문턱값

보다 크거나 동일하면 송신전력을 1로 할당하고, 문턱값

보다 작으면 송신전력을 0으로 할당한다. 이때 문턱값

은 식 10과 같다.According to equation (9), the transmitter 10 has the channel gain parameter magnitude of the legal channel of the receiver 12.

Is the preset threshold

If greater than or equal, transmit power is assigned as 1 and threshold

If it is smaller than 0, transmit power is allocated. The threshold

Is the same as Eq. 10.

이다. 문턱값

는 n_e에 따라 증가하고 snr_e에 따라 점근적 선형 형태(asymptotically linearly)로 증가하지만, snr_r에 역으로 감소(decrease inversely)한다.In equation 10

to be. Threshold

Increases with n _e and increases in asymptotically linearly with snr _e , but decreases inversely with snr _r .

의 방향으로 데이터 신호를 빔포밍한다.The transmitter 220 uses an on-off power allocation scheme to maximize the attainable secure transmission rate.

Beamform the data signal in the direction of.

는

의 분포이다. Bern(p)는 평균(mean) p를 갖는 베르누이 분포(Bernoulli distribution)이다. In Equation 11,

The

Is the distribution. Bern (p) is the Bernoulli distribution with mean p.

3 is a flowchart illustrating a data transmission method of a transmission apparatus according to an embodiment of the present invention.

Referring to FIGS. 1 and 3, the transmitter 10 maximizes the security capacity by differentiating 300 according to whether the channel state information access level for the multiple channels is eavesdropped. Multiple channels include legitimate channels and eavesdropping channels. According to an embodiment, the transmitter 10 accesses all channel state information through a legal channel, and accesses partial channel state information through an eavesdropping channel. The channel capacity for the legal channel is increased and the channel capacity for the eavesdropping channel is reduced to maximize security capacity.

Subsequently, the transmitter 10 allocates the transmit power of the multichannel on-off to maximize the secure transmission rate under the maximized security capacity condition (320). According to an embodiment, the transmission power is allocated based on the number of antennas and the reception signal-to-noise ratio. That is, if the channel gain parameter size of the transmission channel is greater than or equal to a preset threshold, the transmission power may be allocated to 1, and if the channel gain parameter size is smaller than the threshold, the transmission power may be assigned to 0. The threshold is set using the number of antennas of the transmitter, the number of antennas of the eavesdropping device, the signal-to-noise ratio of the receiver and the signal-to-noise ratio of the eavesdropping device.

Subsequently, the transmitter 10 beamforms the data signal according to the transmission power allocation result (330).

The embodiments of the present invention have been described above. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is defined by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

1: multi-channel wireless communication system 10: transmitter
12: receiving device 14: tapping device
200: security capacity setting unit 210: power setting unit
220: transmission unit

Claims (11)

In a method for transmitting data securely transmitting data through multiple channels,
Maximizing security capacity by differentiating a degree of access of channel state information for the multiple channels according to whether the wiretap is performed;
Allocating on-off transmit power of the multi-channel to maximize secure transmission rate under the maximized secure capacity condition; And
Beamforming a data signal according to a result of the transmission power allocation;
Secure data transmission method comprising a. The method of claim 1, wherein allocating the transmission power to on-off includes:
And allocating the transmission power based on the number of antennas and the received signal-to-noise ratio. The method of claim 2, wherein the allocating the transmit power on-off,
If the channel gain parameter size of the transmission channel is greater than or equal to a preset threshold, the transmission power parameter is allocated to 1, and if the channel gain parameter size is smaller than the threshold, the transmission power parameter is assigned to 0. . The method of claim 3, wherein
The threshold value is set using the number of antennas of the transmitter, the number of antennas of the eavesdropping device, the signal-to-noise ratio of the receiver and the signal-to-noise ratio of the eavesdropping device. The method of claim 1, wherein the beamforming of the data signal according to the transmission power allocation result comprises:
And beamforming the data signal in the convolutional direction of a channel gain parameter of a receiver transmission channel by allocating the on-off transmit power. The method of claim 1,
The multichannel includes a legal channel and an eavesdropping channel,
Maximizing the security capacity,
Accessing all channel state information through the legal channel and accessing partial channel state information through the eavesdropping channel; And
Increasing the channel capacity for the legitimate channel and reducing the channel capacity for the eavesdropping channel to maximize the security capacity;
Secure data transmission method comprising a. Multiple input single output multiple taps (MISOME);
A receiver having a single receive antenna;
A transmission apparatus having a plurality of transmission antennas, allocating transmission power of a channel on-off to maximize security transmission rate in the presence of a fading eavesdropping channel of the MISOME, and beamforming a security data signal to the reception device according to the allocation result ;
Multi-channel wireless communication system comprising a. A security capacity setting unit for maximizing the security capacity by differentiating the degree of access to channel state information for multiple channels according to whether the wiretap is performed; And
A power setting unit for allocating transmission power of the multi-channel on-off to maximize a secure transmission rate under the maximized security capacity condition; And
A transmitter for beamforming a data signal according to the transmission power allocation result;
Security data transmission apparatus comprising a. The method of claim 8, wherein the power setting unit,
And allocating the transmission power based on the number of antennas and the received signal-to-noise ratio. 10. The method of claim 9, wherein the power setting unit,
If the magnitude of the channel gain parameter size of the transmission channel is greater than or equal to a predetermined threshold value, the transmission power parameter is allocated to 1, and if the channel gain parameter size is smaller than the threshold value, the transmission power parameter is assigned to 0. Transmitter. 11. The method of claim 10,
And the threshold is set by using the number of antennas of the transmitter, the number of antennas of the eavesdropping device, the signal-to-noise ratio of the receiver and the signal-to-noise ratio of the eavesdropping device.

Images