阅读说明：本技术 一种基于反射放大面对抗同频干扰的方法 (Method for resisting same frequency interference based on reflection amplification surface ) 是由 杜林松 刘颖 符初生 唐友喜 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种基于反射放大面对抗同频干扰的方法,包括以下步骤：S1.构建基于反射放大面对抗同频干扰的通信系统；所述通信系统包括一个发射机、一个接收机、至少一个干扰机和一个放大反射面；S2.给定干扰机的参考功率阈值L,根据干扰机的发射功率P-(I)与参考功率阈值L的大小关系进行发射系数设计：(1)若干扰的发射功率P-(I)大于或等于阈值L,即L≤P-(I),则基于干扰抑制比最小化设计反射系数；(2)若干扰的发射功率P-(I)小于阈值L,即L＞P-(I),则基于系统容量最大化设计反射系数。本发明通过设计放大反射面的系数,有效实现了同频干扰的抑制。(The invention discloses a method for resisting same frequency interference based on a reflection amplification surface, which comprises the following steps: s1, constructing a communication system for resisting same frequency interference based on a reflection amplification surface; the communication system comprises a transmitter, a receiver, at least one jammer and an amplifying reflecting surface; s2, giving a reference power threshold value L of the jammer according to the transmitting power P of the jammer I And designing a transmission coefficient according to the size relation of the reference power threshold L: (1) transmitting power P if interference I Greater than or equal to a threshold value L, i.e. L ≦ P I Designing a reflection coefficient based on the interference rejection ratio minimization; (2) transmitting power P if interference I Less than a threshold value L, i.e. L > P I The reflection coefficient is designed based on the system capacity maximization. The invention effectively realizes the suppression of same frequency interference by designing the coefficient of the amplifying reflecting surface.)

1. A method for resisting same frequency interference based on reflection amplification surface is characterized in that: the method comprises the following steps:

s1, constructing a communication system for resisting same frequency interference based on a reflection amplification surface;

s2, giving a reference power threshold value L of the jammer according to the transmitting power P of the jammer_IAnd designing a transmission coefficient according to the size relation of the reference power threshold L:

(1) transmitting power P if interference_IGreater than or equal to a threshold value L, i.e. L ≦ P_IDesigning a reflection coefficient based on the interference rejection ratio minimization;

(2) transmitting power P if interference_ILess than a threshold value L, i.e. L > P_IThe reflection coefficient is designed based on the system capacity maximization.

2. The method for resisting co-channel interference based on the reflection amplification surface according to claim 1, wherein: the communication system comprises a transmitter, a receiver, at least one jammer and an amplifying reflecting surface;

the amplifying reflecting surface is composed of N amplifying reflectors, each amplifying reflector amplifies and reflects electromagnetic waves and changes the phase of the electromagnetic waves, and the amplification factor alpha is determined by an antenna and a load of the amplifying reflector:

wherein Z_LAnd Z_ARespectively the impedance of the load and the antenna, the impedance of the antenna being

Z_A＝R_A+jX_A

Wherein R is_AThe real part is more than 0 to express the resistance value of the antenna, jX_AThe reactance of the antenna is expressed for the imaginary part; and, under the bias voltage, the load is of a negative resistance property, that is,

Z_L＝-R_L+jX_L

wherein-R_L< 0 is a real number indicating a negative resistance value of the load, jX_LThe reactance of the load is represented for the imaginary part; the magnification factor of the magnifying reflector is therefore:

the amplification factor can be adjusted by adjusting the resistance reactance of the load;

the transmitter transmits a useful signal to the receiver, meanwhile, an interference machine transmits an interference signal to block the receiving of a desired signal, and the amplification reflecting surface is arranged in a communication environment and is used for amplifying the interference signal in the reflection environment, canceling the interference signal in a direct path in an airspace and enhancing the useful signal;

considering only one jammer, the signal received by the receiver is as follows:

whereinIs a vector of channel coefficients from the transmitter to the receiver, is the channel coefficient vector from the jammer to the receiver, is a matrix of channel coefficients from the transmitter to the magnifying reflecting surface, H_T＝[h_T,1,h_T,2,…,h_T,N]^H；Is a matrix of channel coefficients from the transmitter to the magnifying reflecting surface, H_I＝[h_I,1,h_I,2,…,h_I,N]^H,Is the channel coefficient vector from the amplifying reflecting surface to the receiver; g ═ g₁,g₂,…,g_N]^H，Is a diagonal matrix representing the reflection coefficient, z, of each reflection amplifier₀Is desirably 0 and the variance is 1 white noise, andis the noise received by the reflective amplifying surface;

the received signal is substantially equivalent to

Wherein C is_T＝GH_TIs a cascaded channel coefficient matrix of transmitter-amplified reflector-receiver, C_I＝GH_IIs a cascade channel coefficient matrix of jammer-amplified reflector-receiver, G ═ diag [ G [ ]₁,g₂,…,g_N]And a ═ α₁,α₁,…,α_N]^TIs a reflection coefficient vector, and can control an interference channel by designing aMaking its channel gain zero.

3. The method for resisting co-channel interference based on the reflection amplification surface according to claim 2, wherein: the transmitter is a single-antenna or multi-antenna transmitter; the receiver is a single-antenna receiver, and the jammer is a single-antenna or multi-antenna jammer.

4. The method for resisting co-channel interference based on the reflection amplification surface according to claim 2, wherein: the process of designing a reflection coefficient based on interference rejection ratio minimization includes:

first, when the reflection amplifying surface is not used, the interference signal power received by the receiver is asWherein P is_IIs the transmit power of the interference; after using the reflection amplifying surface, the receiver receives the interference signalThe interference rejection ratio is therefore:

secondly, in order to minimize the interference suppression ratio, the following interference suppression ratio minimization problem is proposed:

wherein alpha is_maxIs the maximum value of the reflection coefficient amplitude;

thirdly, designing a group of reflection coefficients according to the problemsA minimized interference rejection ratio is achieved and the mode of the reflection coefficient vector is minimized, i.e. the reflection surface energy consumption is minimized. Coefficient of reflectionComprises the following steps:

whereinAnd isBy means of a pair matrixPerforming maximum rank decompositionGiven that r is a matrixIs determined.

5. The method for resisting co-channel interference based on the reflection amplification surface according to claim 4, wherein: when the matrix C is_IWhen the matrix is a row full rank matrix, N is more than or equal to M_IWhen r, the designed reflection coefficient is:

corresponding self-interference rejection ratio of

Thereby, self-interference is completely suppressed.

6. The method for resisting co-channel interference based on the reflection amplification surface according to claim 4, wherein: when the number of the jammers is K, the interference rejection ratio becomes

WhereinAnd isP_kIs the transmit power of the kth jammer,is the channel coefficient vector, C, from the kth jammer to the receiver_kIs a coefficient matrix of a kth jammer-amplification reflecting surface-receiver cascade channel;

reflection coefficient becomes

WhereinAnd isBy pairsPerforming maximum rank decompositionGiven, where r is a matrixIs determined.

7. The method for resisting co-channel interference based on the reflection amplification surface according to claim 2, wherein: the process of designing the reflection coefficient based on the system capacity maximization comprises the following steps:

given a set of reflection coefficients a ═ α₁,α₁,…,α_N]^TThe channel capacity under interference is:

wherein P is_TIs the transmit power of the transmitter, in order to maximize capacity, the signal to interference plus noise ratio is maximized because log (-) is a monotonically increasing function

The problem of maximizing the SINR is a non-convex problem, and the optimal reflection coefficient a is obtained by the following algorithm^*To maximize the capacity of the communication scenario.

First, gamma is fixed, and the problem (9) is transformed into

And is provided with a^(γ)For the optimal solution of the problem (10), when f (γ) is 0, γ is obtained as γ ═ γ^*And the corresponding problem (9) is the same as the optimal solution of the problem (10), i.e., a^*＝a(γ^*)；

The function f (γ) is a monotonically increasing function, so the problem (9) is solved by a binary iteration method, where each iteration, the problem (10) is solved; and the solution after the last iterationIs a parameter of the current iteration; in the ith iteration, the second term of the objective function (10) of the linearization problem, i.e.,to obtain

Wherein a is_i-1Is the optimal solution of the (i-1) th iteration, namely the optimal solution after the last iteration, when a is fixed_i-1Then, function g (a, a)_i-1) Regarding the variable a as a convex function, the optimal solution for the current iteration is obtained by solving the following problem:

wherein a is_iIs the optimal solution when the i-th iteration is performed, because the problem (12) is a convex problem, the solution using CVX solves the optimal reflection coefficient a based on the capacity maximization^*Comprises the following steps:

a1: parameter initialization gamma_low＝0，Current channel coefficient t_T，t_I，g，H_T，H_ITransmitting power P_TOf the jammer transmit power P_ITolerance error sigma₁，σ₂The output of the ith iteration is θ_λiAnd G (lambda)_i)

A2: if | γ_j-γ_j-1If | > sigma, enter A6;

a21: if a_i-a_i-1If | > sigma, enter A3;

a22: calculation of a by CVX_i+1＝argmin_ag(a,a_i)；

A22: returning to A21;

a3: so thatAnd pass throughCalculating f (gamma)_j)；

A4: if f (gamma)_j) > 0, then result inAnd gamma is_low＝γ_i(ii) a If f (gamma)_j) Less than 0, thenAnd gamma is_up＝γ_i；

A5: entering A2;

a6: order to

8. The method for resisting co-channel interference based on the reflection amplification surface according to claim 7, wherein: when the number of the jammers is plural, equation (9) becomes:

Technical Field

The invention relates to the field of communication, in particular to a method for resisting same frequency interference based on a reflection amplification surface.

Background

In a real communication scene, a receiver receives a co-channel interference signal from an interference source, so that the signal-to-noise ratio is reduced, the error rate is improved, and even a channel is blocked, so that a useful signal cannot be normally received. For example, in a high-density 5G cellular network, base stations often operate on the same frequency due to the scarcity of spectrum resources. Meanwhile, because of the high density of cellular networks, the edge mobile users of the cell are closer to the base station of the adjacent cell and are interfered by other base stations. In addition, full duplex technology also generates co-channel interference, i.e., self-interference. In a battlefield environment, military communication equipment is subject to active interference from even hostile jammers with a high probability. Furthermore, in the complex environment of a battlefield, even a friend transmitter may interfere with reception at the receiver due to lack of coordination.

The existing anti-interference technologies are roughly divided into two types: 1) interference reconstruction cancellation techniques; 2) interference alignment techniques for multi-antenna systems. The interference reconstruction cancellation technique is generally applied to full-duplex scenarios: the full-duplex transceiver reconstructs the interference signal transmitted by the full-duplex transceiver, and the reconstructed signal is used in an analog domain and a digital domain to reduce the self-interference signal received by the receiving antenna. However, this approach requires the receiver to know the own transmitted interfering signal for reconstruction and is therefore generally used for full duplex techniques. The interference alignment technology means that an interference machine enables an interference signal to fall in an interference subspace of a receiver through a precoding matrix, and a useful signal vector is independent of the interference subspace. The receiver then designs its receive matrix such that the interference is forced to zero. However, this approach requires the jammer to be co-located with the receiver, i.e. the jammer must be a partner, so it is not effective against malicious interference. Furthermore, under some channel conditions, the jammer and the receiver cannot find a suitable precoding matrix so that the interference is forced to zero.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for resisting same frequency interference based on a reflection amplification surface, and the suppression of the same frequency interference is effectively realized by designing the coefficient of the amplification reflection surface.

The purpose of the invention is realized by the following technical scheme: a method for resisting same frequency interference based on a reflection amplification surface comprises the following steps:

s1, constructing a communication system for resisting same frequency interference based on a reflection amplification surface;

s2, giving a reference power threshold value L of the jammer according to the transmitting power P of the jammer_IAnd designing a transmission coefficient according to the size relation of the reference power threshold L:

(1) transmitting power P if interference_IGreater than or equal to a threshold value L, i.e. L ≦ P_IDesigning a reflection coefficient based on the interference rejection ratio minimization;

(2) transmitting power P if interference_ILess than a threshold value L, i.e. L > P_IThe reflection coefficient is designed based on the system capacity maximization.

Wherein, the communication system comprises a transmitter, a receiver, at least one interference machine and an amplifying reflecting surface;

the amplifying reflecting surface is composed of N amplifying reflectors, each amplifying reflector amplifies and reflects electromagnetic waves and changes the phase of the electromagnetic waves, and the amplification factor alpha is determined by an antenna and a load of the amplifying reflector:

wherein Z_LAnd Z_ARespectively the impedance of the load and the antenna, the impedance of the antenna being

Z_A＝R_A+jX_A

Wherein R is_AThe real part is more than 0 to express the resistance value of the antenna, jX_AThe reactance of the antenna is expressed for the imaginary part; and, under the bias voltage, the load is of a negative resistance property, that is,

Z_L＝-R_L+jX_L

wherein-R_L< 0 is a real number indicating a negative resistance value of the load, jX_LThe reactance of the load is represented for the imaginary part; the magnification factor of the magnifying reflector is therefore:

the amplification factor can be adjusted by adjusting the resistance reactance of the load;

the transmitter transmits a useful signal to the receiver, meanwhile, an interference machine transmits an interference signal to block the receiving of a desired signal, and the amplification reflecting surface is arranged in a communication environment and is used for amplifying the interference signal in the reflection environment, canceling the interference signal in a direct path in an airspace and enhancing the useful signal;

considering only one jammer, the signal received by the receiver is as follows:

whereinIs a vector of channel coefficients from the transmitter to the receiver,is the channel coefficient vector from the jammer to the receiver,is a matrix of channel coefficients from the transmitter to the magnifying reflecting surface, H_T＝[h_T,1,h_T,2,…,h_T,N]^H；Is a matrix of channel coefficients from the transmitter to the magnifying reflecting surface, H_I＝[h_I,1,h_I,2,…,h_I,N]^H,Is the channel coefficient vector from the amplifying reflecting surface to the receiver; g ═ g₁,g₂,…,g_N]^H，Is a diagonal matrix representing the reflection coefficient, z, of each reflection amplifier₀Is desirably 0 and the variance is 1 white noise, andis the noise received by the reflective amplifying surface;

the received signal is substantially equivalent to

Wherein C is_T＝GH_TIs a cascaded channel coefficient matrix of transmitter-amplified reflector-receiver, C_I＝GH_IIs a cascade channel coefficient matrix of jammer-amplified reflector-receiver, G ═ diag [ G [ ]₁,g₂,…,g_N]And a ═ α₁,α₁,…,α_N]^TIs a reflection coefficient vector, and can control an interference channel by designing aMaking its channel gain zero.

Preferably, the transmitter is a single antenna or a multi-antenna transmitter; the receiver is a single-antenna receiver, and the jammer is a single-antenna or multi-antenna jammer.

The process of designing a reflection coefficient based on interference rejection ratio minimization includes:

first, when the reflection amplifying surface is not used, the interference signal power received by the receiver is asWherein P is_IIs the transmit power of the interference; after using the reflection amplifying surface, the receiver receives the interference signalThe interference rejection ratio is therefore:

secondly, in order to minimize the interference suppression ratio, the following interference suppression ratio minimization problem is proposed:

wherein alpha is_maxIs the maximum value of the reflection coefficient amplitude;

thirdly, designing a group of reflection coefficients according to the problemsThe minimized interference rejection ratio is realized, and the mode of the reflection coefficient vector is minimized, namely, the energy consumption of the reflection surface is minimized, and the reflection coefficientComprises the following steps:

whereinAnd isBy means of a pair matrixPerforming maximum rank decompositionGiven that r is a matrixIs determined.

Preferably, when said matrix C is_IIs aWhen a row is full rank matrix, N is more than or equal to M_IWhen r, the designed reflection coefficient is:

corresponding self-interference rejection ratio of

Thereby, self-interference is completely suppressed.

Preferably, when the number of jammers is K, the interference rejection ratio becomes

WhereinAnd isP_kIs the transmit power of the kth jammer,is the channel coefficient vector, C, from the kth jammer to the receiver_kIs a coefficient matrix of a kth jammer-amplification reflecting surface-receiver cascade channel;

reflection coefficient becomes

WhereinAnd isBy pairsPerforming maximum rank decompositionGiven, where r is a matrixIs determined.

The process of designing the reflection coefficient based on the system capacity maximization comprises the following steps:

given a set of reflection coefficients a ═ α₁,α₁,…,α_N]^TThe channel capacity under interference is:

wherein P is_TIs the transmit power of the transmitter, in order to maximize capacity, the signal to interference plus noise ratio is maximized because log (-) is a monotonically increasing function

s.t.|α_n|≤α_max,n＝1,…,N

The problem of maximizing the SINR is a non-convex problem, and the optimal reflection coefficient a is obtained by the following algorithm^*To maximize the capacity of the communication scenario.

First, gamma is fixed, and the problem (9) is transformed into

And is provided with a^(γ)For the optimal solution of the problem (10), when f (γ) is 0, γ is obtained as γ ═ γ^*And corresponding problem (9) and optimal solution of problem (10)As such, that is,

the function f (γ) is a monotonically increasing function, so the problem (9) is solved by a binary iteration method, where each iteration, the problem (10) is solved; the solution after the last iteration is taken as a parameter of the current iteration; in the ith iteration, the second term of the objective function (10) of the linearization problem, i.e.,to obtain

Wherein a is_i-1Is the optimal solution of the (i-1) th iteration, namely the optimal solution after the last iteration, when a is fixed_i-1Then, function g (a, a)_i-1) Regarding the variable a as a convex function, the optimal solution for the current iteration is obtained by solving the following problem:

wherein a is_iIs the optimal solution when the ith iteration is performed, because the problem (12) is a convex problem, the optimal reflection coefficient a based on capacity maximization can be solved by using CVX and the like and a convex optimization tool^*Comprises the following steps:

a1: parameter initialization gamma_low＝0，Current channel coefficient t_T，t_I，g，H_T，H_ITransmitting power P_TOf the jammer transmit power P_ITolerance error sigma₁，σ₂The output of the ith iteration is θ_λiAnd G (lambda)_i)

A2: if | γ_j-γ_j-1If | is greater than σ, thenA6;

a21: if a_i-a_i-1If | > sigma, enter A3;

a22: calculation of a by CVX_i+1＝argmin_ag(a,a_i)；

A22: returning to A21;

a3: so thatAnd pass throughCalculating f (gamma)_j)；

A4: if f (gamma)_j) > 0, then result inAnd gamma is_low＝γ_i(ii) a If f (gamma)_j) Less than 0, thenAnd gamma is_up＝γ_i；

A5: entering A2;

a6: order to

Preferably, when the number of jammers is plural, equation (9) becomes:

s.t.|α_n|≤α_max,n＝1,…,N

the invention has the beneficial effects that: the invention effectively realizes the suppression of same frequency interference by designing the coefficient of the amplifying reflecting surface and according to the transmitting power P of the jammer_IDesigning a transmission coefficient in relation to the size of a reference power threshold L, and designing the transmission power P of the jammer_IGreater than or equal to a threshold value L, based on an interference rejection ratioMinimizing the design reflection coefficient; at the transmission power P of the interference_IThe reflection coefficient is designed based on the system capacity maximization when the reflection coefficient is smaller than the threshold L, so that only the interference signal is inhibited when the power of the interference signal is large, and the operation process is simplified; when the interference signal power is small, suppressing only the interference signal does not significantly improve the system performance, and therefore a larger transmission rate gain is obtained with the system capacity as a target.

Drawings

FIG. 1 is a flow chart of a method of the present invention;

FIG. 2 is a schematic diagram of a constructed communication system;

fig. 3 is a schematic view of the principle of an enlarged reflector.

Detailed Description

The technical solutions of the present invention are further described in detail below with reference to the accompanying drawings, but the scope of the present invention is not limited to the following.

As shown in fig. 1, a method for combating co-channel interference based on reflection amplification surface includes the following steps:

s1, constructing a communication system for resisting same frequency interference based on a reflection amplification surface;

s2, giving a reference power threshold value L of the jammer according to the transmitting power P of the jammer_IAnd designing a transmission coefficient according to the size relation of the reference power threshold L:

(1) transmitting power P if interference_IGreater than or equal to a threshold value L, i.e. L ≦ P_IDesigning a reflection coefficient based on the interference rejection ratio minimization;

(2) transmitting power P if interference_ILess than a threshold value L, i.e. L > P_IThe reflection coefficient is designed based on the system capacity maximization.

As shown in fig. 2, the communication system includes a transmitter, a receiver, at least one jammer, and an amplifying reflecting surface;

the amplifying and reflecting surface is composed of N amplifying reflectors, each amplifying reflector amplifies and reflects electromagnetic waves and changes the phase of the electromagnetic waves, the principle of each amplifying reflector is shown in FIG. 3, and the amplification factor alpha is determined by an antenna and a load of the amplifying reflector:

wherein Z_LAnd Z_ARespectively the impedance of the load and the antenna, the impedance of the antenna being

Z_A＝R_A+jX_A

Wherein R is_AThe real part is more than 0 to express the resistance value of the antenna, jX_AThe reactance of the antenna is expressed for the imaginary part; and, under the bias voltage, the load is of a negative resistance property, that is,

Z_L＝-R_L+jX_L

wherein-R_L< 0 is a real number indicating a negative resistance value of the load, jX_LThe reactance of the load is represented for the imaginary part; the magnification factor of the magnifying reflector is therefore:

the amplification factor can be adjusted by adjusting the resistance reactance of the load;

the transmitter transmits a useful signal to the receiver, meanwhile, an interference machine transmits an interference signal to block the receiving of a desired signal, and the amplification reflecting surface is arranged in a communication environment and is used for amplifying the interference signal in the reflection environment, canceling the interference signal in a direct path in an airspace and enhancing the useful signal;

considering only one jammer, the signal received by the receiver is as follows:

whereinIs a vector of channel coefficients from the transmitter to the receiver,is the channel coefficient vector from the jammer to the receiver,is a matrix of channel coefficients from the transmitter to the magnifying reflecting surface, H_T＝[h_T,1,h_T,2,…,h_T,N]^H；Is a matrix of channel coefficients from the transmitter to the magnifying reflecting surface, H_I＝[h_I,1,h_I,2,…,h_I,N]^H,Is the channel coefficient vector from the amplifying reflecting surface to the receiver; g ═ g₁,g₂,…,g_N]^H，Is a diagonal matrix representing the reflection coefficient, z, of each reflection amplifier₀Is desirably 0 and the variance is 1 white noise, andis the noise received by the reflective amplifying surface;

the received signal is substantially equivalent to

Wherein C is_T＝GH_TIs a cascaded channel coefficient matrix of transmitter-amplified reflector-receiver, C_I＝GH_IIs a cascade channel coefficient matrix of jammer-amplified reflector-receiver, G ═ diag [ G [ ]₁,g₂,…,g_N]And a ═ α₁,α₁,…,α_N]^TIs a reflection coefficient vector, and can control an interference channel by designing aMaking its channel gain zero.

In an embodiment of the present application, the transmitter is a single antenna or a multiple antenna transmitter; the receiver is a single-antenna receiver, and the jammer is a single-antenna or multi-antenna jammer.

The process of designing a reflection coefficient based on interference rejection ratio minimization includes:

first, when the reflection amplifying surface is not used, the interference signal power received by the receiver is asWherein P is_IIs the transmit power of the interference; after using the reflection amplifying surface, the receiver receives the interference signalThe interference rejection ratio is therefore:

secondly, in order to minimize the interference suppression ratio, the following interference suppression ratio minimization problem is proposed:

wherein alpha is_maxIs the maximum value of the reflection coefficient amplitude;

thirdly, designing a group of reflection coefficients according to the problemsThe minimized interference rejection ratio is realized, and the mode of the reflection coefficient vector is minimized, namely, the energy consumption of the reflection surface is minimized, and the reflection coefficientComprises the following steps:

whereinAnd isBy means of a pair matrixPerforming maximum rank decompositionGiven that r is a matrixIs determined.

In the embodiment of the present application, when the matrix C_IWhen the matrix is a row full rank matrix, N is more than or equal to M_IWhen r, the designed reflection coefficient is:

corresponding self-interference rejection ratio of

Thereby, self-interference is completely suppressed.

In the embodiment of the present application, when the number of jammers is K, the interference rejection ratio becomes

WhereinAnd isP_kIs the transmit power of the kth jammer,is the channel coefficient vector, C, from the kth jammer to the receiver_kIs a coefficient matrix of a kth jammer-amplification reflecting surface-receiver cascade channel;

reflection coefficient becomes

WhereinAnd isBy pairsPerforming maximum rank decompositionGiven, where r is a matrixIs determined. WhereinIs A_IThe conjugate transpose matrix of (2).

The reflection amplification surface can not only inhibit interference but also enhance useful signals, so in order to maximize the performance of a communication system, a reflection coefficient design method which has maximized system capacity is provided:

first, a system model is available, and the process of designing the reflection coefficient based on the system capacity maximization comprises the following steps:

given a set of reflection coefficients a ═ α₁,α₁,…,α_N]^TThe channel capacity under interference is:

wherein P is_TIs the transmit power of the transmitter, in order to maximize capacity, the signal to interference plus noise ratio is maximized because log (-) is a monotonically increasing function

The problem of maximizing the SINR is a non-convex problem, and the optimal reflection coefficient a is obtained by the following algorithm^*To maximize the capacity of the communication scenario.

First, gamma is fixed, and the problem (9) is transformed into

And is provided with a^(γ)For the optimal solution of the problem (10), when f (γ) is 0, γ is obtained as γ ═ γ^*And the corresponding problem (9) is the same as the optimal solution of the problem (10), i.e.,

the function f (γ) is a monotonically increasing function, so the problem (9) is solved by a binary iteration method, where each iteration, the problem (10) is solved; problem (10) is also a Convex-Concave problem, which can be solved by (Convex-Concave-procedure, CCP) technique. The CCP technique is an iterative algorithm that solves the approximation of the problem (10) each iteration. The solution after the last iteration is taken as a parameter of the current iteration; in the ith iteration, linearizeThe second term of the objective function (10) of the problem, i.e.,to obtain

Wherein a is_i-1Is the optimal solution of the (i-1) th iteration, namely the optimal solution after the last iteration, when a is fixed_i-1Then, function g (a, a)_i-1) Regarding the variable a as a convex function, the optimal solution for the current iteration is obtained by solving the following problem:

wherein a is_iIs the optimal solution when the ith iteration is performed, because the problem (12) is a convex problem, the optimal reflection coefficient a based on capacity maximization can be solved by using CVX and the like and a convex optimization tool^*Comprises the following steps:

a1: parameter initialization gamma_low＝0，Current channel coefficient t_T，t_I，g，H_T，H_ITransmitting power P_TOf the jammer transmit power P_ITolerance error sigma₁，σ₂The output of the ith iteration isAnd G (lambda)_i)

A2: if | γ_j-γ_j-1If | > sigma, enter A6;

a21: if a_i-a_i-1If | > sigma, enter A3;

a22: calculation of a by CVX_i+1＝argmin_ag(a,a_i)；

A22: returning to A21;

a3: so thatAnd pass throughCalculating f (gamma)_j)；

A4: if f (gamma)_j) > 0, then result inAnd gamma is_low＝γ_i(ii) a If f (gamma)_j) Less than 0, thenAnd gamma is_up＝γ_i；

A5: entering A2;

a6: order to

In the embodiment of the present application, when the number of jammers is plural, equation (9) becomes:

s.t.|α_n|≤α_max,n＝1,…,N

after the reflection coefficient is designed to be amplified, the amplification emission coefficient can be adjusted to a set value by adjusting the resistance reactance of the load.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.