Transmit beamforming method and system based on engineered analog transmit-receive simultaneous array

Abstract

The application discloses a transmitting beam forming method and system based on an engineered analog transmit-receive simultaneous array, and the method comprises the following steps: measuring the attenuator response and the phase shifter response of the transmitting array of the transmit-receive simultaneous array, and constructing a transmit-receive simultaneous array beam forming weight lookup table; determining the effective isotropic radiated power; pre-setting the inter-antenna coupling matrix of the transmit-receive simultaneous array, combining the effective isotropic radiated power, the initial transmitting beam forming vector and the transmit-receive simultaneous array beam forming weight lookup table, and constructing an optimization problem; and optimizing the initial transmitting beam forming vector based on the optimization problem to obtain the optimized target transmitting beam forming vector. The application can consider the response of the real world analog attenuator and phase shifter to optimize the beam weight, and improve the accuracy of the target transmitting beam forming vector. The application can be widely applied to the field of wireless communication technology as the transmitting beam forming method and system based on the engineered analog transmit-receive simultaneous array.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication, in particular to a transmit beamforming method and system based on an engineered simultaneous transmit-receive array. BACKGROUND

[0002] Simultaneous transmit-receive technology, also known as in-band full-duplex technology, has the ability to simultaneously complete signal transmission and reception on the same frequency band, which can double the spectrum utilization rate and greatly alleviate the shortage of spectrum resources. The severe challenge of simultaneous transmit-receive technology is that the transmitted signal will cause strong self-interference to the received signal. These self-interference signals can easily saturate the receiver and then drown the interested signal. With the continuous progress of technology, research on self-interference signal suppression mainly focuses on three dimensions: propagation domain, analog domain, and digital domain. However, compared with digital domain methods, the isolation effect achieved by antenna and analog domain methods is relatively limited. Especially in large-scale phased arrays with strong self-interference of multi-dimensional cross-coupling from the transmit end to the receive end, radio frequency cancellation will add high costs to the system in terms of size, complexity, and power consumption. Beamforming is an efficient technology that can improve the isolation of STAR phased arrays from the spatial domain. Numerous studies have proposed various algorithms for different types of arrays, effectively achieving isolation of self-interference signals in the spatial domain. STAR phased arrays can be divided into three beamforming architectures: digital beamforming, analog beamforming, and hybrid beamforming. Considering the cost of phased arrays, most real-world phased arrays use analog beamforming architecture rather than digital beamforming, resulting in errors in the control of beamforming weights. SUMMARY

[0003] To solve the above technical problems, the purpose of the present application is to provide a transmit beamforming method and system based on an engineered simultaneous transmit-receive array, which can consider the response of real-world analog attenuators and phase shifters to optimize beam weights and improve the accuracy of target transmit beamforming vectors.

[0004] The first technical solution adopted by the present application is: a transmit beamforming method based on an engineered simultaneous transmit-receive array, comprising the following steps:

[0005] Measuring the attenuator response and phase shifter response of the transmit array of the simultaneous transmit-receive array, and constructing a simultaneous transmit-receive array beamforming weight lookup table;

[0006] Obtaining the initial transmit beamforming vector, steering vector, and maximum single-link transmit power of the transmit array of the simultaneous transmit-receive array, and determining the effective isotropic radiated power;

[0007] An inter-antenna coupling matrix of the pre-configured transceiving-simultaneous array is preset, and an optimization problem is constructed in combination with an effective isotropic radiated power, an initial transmit beamforming vector and a transceiving-simultaneous array beamforming weight lookup table;

[0008] The initial transmit beamforming vector is optimized based on the optimization problem to obtain an optimized target transmit beamforming vector.

[0009] Further, the step of measuring the attenuator response and the phase shifter response of the transmit array of the transceiving-simultaneous array and constructing the transceiving-simultaneous array beamforming weight lookup table specifically comprises:

[0010] The attenuator response and the phase shifter response of the transmit array of the transceiving-simultaneous array are measured;

[0011] The attenuator response and the phase shifter response are multiplied to construct the transceiving-simultaneous array beamforming weight lookup table;

[0012] The expression of the transceiving-simultaneous array beamforming weight lookup table is specifically as follows:

[0013]

[0014] In the above formula, represents a transceiving-simultaneous array optional beamforming weight lookup table, represents an attenuator response of a transceiving-simultaneous array transmit component, represents a phase shifter response of the transceiving-simultaneous array transmit component, N a represents the number of bits of a digital attenuator, N p represents the number of bits of a digital phase shifter, [·] :,j represents a matrix slice, (·) T represents a matrix transpose.

[0015] Further, the step of obtaining an initial transmit beamforming vector, a steering vector and a maximum single-link transmit power of a transmit array of a transceiving-simultaneous array and determining an effective isotropic radiated power specifically comprises:

[0016] The transmit beamforming vector is initialized to obtain an initial transmit beamforming vector;

[0017] The expected beam pointing angle is determined, and the steering vector and the maximum single-link transmit power of the transmit array are obtained;

[0018] The effective isotropic radiated power is determined according to the expected beam pointing angle, the steering vector of the transmit array and the initial transmit beamforming vector.

[0019] Further, the expression of the effective isotropic radiated power is specifically as follows:

[0020]

[0021] In the above formula, φ represents an azimuth angle in a spherical coordinate system, and θ represents a pitch angle in the spherical coordinate system, represents a transmit beamforming vector, represents a steering vector of a transmit array, H represents a conjugate transpose of a matrix, g t represents a directional pattern of a transmit array element.

[0022] Further, the step of pre-setting the inter-antenna coupling matrix of the transceiving simultaneous array, combining the effective isotropic radiated power, the initial transmit beamforming vector and the transceiving simultaneous array beamforming weight lookup table, constructing an optimization problem, specifically includes:

[0023] pre-setting the inter-antenna coupling matrix of the transceiving simultaneous array;

[0024] determining the self-interference signal power of the receive array element according to the inter-antenna coupling matrix of the transceiving simultaneous array and the initial transmit beamforming vector;

[0025] determining the transmit array gain pattern according to the effective isotropic radiated power, and setting a target function in combination with the self-interference signal power of the receive array element;

[0026] obtaining the total transmit power of the transmit array and setting a first constraint condition;

[0027] setting a second constraint condition according to the transceiving simultaneous array beamforming weight lookup table;

[0028] constructing an optimization problem according to the first constraint condition, the second constraint condition and the target function.

[0029] Further, the step of pre-setting the inter-antenna coupling matrix of the transceiving simultaneous array, specifically includes:

[0030] obtaining the propagation coefficient of the transmit array to the receive array element in the transceiving simultaneous array, the total number of transmit links and the total number of receive links;

[0031] pre-setting the inter-antenna coupling matrix of the transceiving simultaneous array according to the propagation coefficient, the total number of transmit links and the total number of receive links;

[0032] The expression of the inter-antenna coupling matrix of the transceiving simultaneous array is specifically as follows:

[0033]

[0034] In the above formula, S k,j represents the propagation coefficient of the transmit array element j to the receive array element k, and J and K represent the total number of transmit and receive links, respectively.

[0035] Further, the expression of the self-interference signal power of the receiving array element is specifically as follows:

[0036]

[0037] In the above formula, represents the self-interference component power at the receiving antenna, represents the ideal transceiving antenna intercoupling matrix of the transceiving simultaneous array, Diag(·) represents a function of taking diagonal elements of a square matrix to form a vector or converting a vector into a diagonal matrix, η t represents the signal-to-noise ratio of the transmitting link.

[0038] The expression of the optimization problem is specifically as follows:

[0039]

[0040] In the above formula, f in formula (1) is an objective function of the optimization problem, and the maximum transmitting pattern gain and the minimum self-interference signal power at each receiving array element are maximized, the self-interference power in the denominator is the sum of the self-interference powers at each receiving antenna, formula (2) and formula (3) are constraint conditions, formula (2) constrains the transmitting power of the transmitting link to be less than the maximum transmitting power of the single link, and formula (3) constrains the discrete value range of the analog beamforming weight to be within the lookup table.

[0041] Further, the step of optimizing the initial transmitting beamforming vector based on the optimization problem to obtain the optimized target transmitting beamforming vector specifically includes:

[0042] Relaxing the optimization problem to remove the constraint condition of the discrete value range of the analog beamforming weight to obtain a solvable optimization problem;

[0043] Carrying out secondary optimization on the solvable optimization problem to obtain a relaxed optimization problem;

[0044] Solving the relaxed optimization problem to obtain an upper bound of the optimization problem and an optimal solution of the transmitting beamforming vector;

[0045] Dividing the transceiving simultaneous array beamforming weight lookup table by the optimal solution of the transmitting beamforming vector to obtain a division result;

[0046] Based on the upper bound of the optimization problem, the phases of the division result are sorted, and a subspace in which the error of the phase and the optimal solution is within a preset range is reserved;

[0047] The amplitudes of the subspace are sorted, and the result closest to the optimal solution in amplitude is reserved as an optimization result, and the optimized target transmitting beamforming vector is output.

[0048] The second technical solution adopted by the present application is: a transmitting beamforming system based on an engineered simultaneous transmit-receive array, comprising:

[0049] A first module for measuring the attenuator response and phase shifter response of the transmitting array of the simultaneous transmit-receive array and constructing a simultaneous transmit-receive array beamforming weight lookup table;

[0050] A second module for obtaining the initial transmitting beamforming vector, steering vector and maximum single-link transmitting power of the transmitting array of the simultaneous transmit-receive array and determining the effective omnidirectional radiation power;

[0051] A third module for pre-setting the inter-antenna coupling matrix of the simultaneous transmit-receive array, combining the initial transmitting beamforming vector with the simultaneous transmit-receive array beamforming weight lookup table and constructing an optimization problem;

[0052] A fourth module for optimizing the initial transmitting beamforming vector based on the optimization problem to obtain the optimized target transmitting beamforming vector.

[0053] The present application has the following beneficial effects: the present application measures the attenuator response and phase shifter response of the transmitting array of the simultaneous transmit-receive array and constructs a simultaneous transmit-receive array beamforming weight lookup table, uses a computer to control the numerical control attenuator and phase shifter of the vector network analyzer and transmitting component and measure the S parameters of all attenuation and phase shift states, generates a lookup table of actual attenuation and phase shift at the working frequency according to the measured S parameters, optimizes the self-interference suppression beamforming according to the lookup table, further obtains the initial transmitting beamforming vector, steering vector and maximum single-link transmitting power of the transmitting array of the simultaneous transmit-receive array and determines the effective omnidirectional radiation power, further pre-sets the inter-antenna coupling matrix of the simultaneous transmit-receive array, combines the initial transmitting beamforming vector with the simultaneous transmit-receive array beamforming weight lookup table and constructs an optimization problem, takes minimizing the maximum incident power of all receiving elements and maximizing the transmitting gain pattern as the optimization target, takes the single-channel maximum transmitting power and the weight value in the lookup table as the constraint condition, establishes the optimization problem of the analog beamforming, finally optimizes the initial transmitting beamforming vector based on the optimization problem to obtain the optimized target transmitting beamforming vector, relaxes the constraint condition of the optimization problem, converts the optimization problem into an easy-to-solve form, then uses the subspace ordering search method to solve the beamforming weight optimization result satisfying all constraint conditions, can consider the response of the real-world analog attenuator and phase shifter to optimize the beam weight and improve the accuracy of the target transmitting beamforming vector. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is the step flow chart of the transmitting beamforming method of the present application based on the engineered simultaneous transmit-receive array;

[0055] Figure 2 is a structural block diagram of the transmit beamforming system based on the engineered analog transmit-receive simultaneous array according to the present application;

[0056] Figure 3 is a step schematic diagram of the transmit beamforming provided by the embodiment of the present application;

[0057] Figure 4 is a transmit-receive simultaneous array structure and signal schematic diagram provided by the embodiment of the present application;

[0058] Figure 5 is an attenuator response and a phase shifter response automatic measurement schematic diagram.

[0059] Figure 6 is a schematic diagram of the S21 amplitude of the transmit channel when the digital attenuator is controlled to different attenuation values provided by the embodiment of the present application;

[0060] Figure 7 is a schematic diagram of the S21 phase of the transmit channel when the digital attenuator is controlled to different attenuation values provided by the embodiment of the present application;

[0061] Figure 8 is a schematic diagram of the S21 phase of the transmit channel when the digital phase shifter is controlled to different phase shift values provided by the embodiment of the present application;

[0062] Figure 9 is a schematic diagram of the S21 amplitude of the transmit channel when the digital phase shifter is controlled to different phase shift values provided by the embodiment of the present application;

[0063] Figure 10 is an attenuator response and a phase shifter response schematic diagram of the attenuation phase lookup table (amplitude) of the 7GHz transmit channel 1 generated after the measurement;

[0064] Figure 11 is an attenuator response and a phase shifter response schematic diagram of the attenuation phase lookup table (phase) of the 7GHz transmit channel 1 generated after the measurement;

[0065] Figure 12 is a schematic diagram of the maximum self-interference of all receive antennas in all beam directions under different operating frequencies provided by the embodiment of the present application;

[0066] Figure 13 is a schematic diagram of the direction of the beam direction -5° under different operating frequencies provided by the embodiment of the present application;

[0067] Figure 14 is a standard deviation diagram of actual attenuator phase shifter characteristics at different working frequencies provided by specific embodiments of the present application;

[0068] Figure 15 is a diagram of actual measurement results of self-interference suppression beamforming provided by specific embodiments of the present application; DETAILED DESCRIPTION

[0069] The application will be further described below in conjunction with the drawings and specific embodiments. For the step numbers in the following embodiments, they are only set for the convenience of description, and the order between the steps is not limited in any way, and the execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0070] Before the embodiments of the present application are described in detail, first, some nouns and terms involved in the embodiments of the present application are described, and the nouns and terms involved in the embodiments of the present application are applicable to the following explanations.

[0071] 1) Simultaneous Transmit and Receive (STAR): a technology of transmitting and receiving electromagnetic wave signals in the same radio system, same time and same frequency band, also known as In-Band Full-Duplex (IBFD).

[0072] 2) Receive-Transmit (R / T) Isolation: refers to the ratio of the power coupling (leakage) of the transmit channel to the receive channel in the antenna duplexer, usually represented by I. The receive-transmit isolation is a measure of the power leakage from the transmit channel to the receive channel, equal to the ratio of the input power of the transmit channel to the power leaked to the receive channel, and its unit is usually expressed in dB.

[0073] 3) Self-Interference Cancellation (SIC): refers to the process of suppressing strong self-interference signals from the transmitting end in different parts of the simultaneous transmit and receive system, including the propagation domain, the analog domain and the digital domain. Self-interference cancellation is the key to realizing the simultaneous transmit and receive technology.

[0074] 4) Adaptive Beamforming (ABF): refers to dynamically adjusting the beamforming vector so that the transmit or receive beam is adapted to the actual channel environment and requirements, which has the same meaning as beamforming optimization. The ABF mentioned in the embodiments of the present application refers to the adaptive transmit and receive beamforming optimization before and after.

[0075] In the field of transceiving simultaneous array system at present stage, the following problems mainly exist:

[0076] 1) The self-interference signal generated by the transmitting end will saturate the low noise amplifier (LNA) of the receiving radio frequency front end, generate a large number of nonlinear components, and also saturate the receiving ADC, so that the interested signal cannot be correctly received.

[0077] 2) The analog beamforming uses analog attenuators and phase shifters to control the weights of beamforming, but the precision of analog attenuators and phase shifters is limited, which leads to the performance degradation of self-interference suppression.

[0078] 3) The attenuation step and inherent phase shift of real-world analog attenuators are different under different attenuation states and working frequencies, and the phase shift step and inherent attenuation of real-world analog phase shifters are different under different phase shift states and working frequencies, which leads to errors in the control of beamforming weights.

[0079] Based on this, the embodiment of the present application proposes a kind of engineering analog transceiving simultaneous array transmitting beamforming implementation method, consider the response of real-world analog attenuator and phase shifter to optimize beam weight, with higher engineering practicability, first, using computer control vector network analyzer and the numerical control attenuator and phase shifter of transmitting component and measure the S parameter of all attenuation and phase shift state.According to the S parameter measured, the look-up table of actual attenuation phase shift on working frequency is generated, and the look-up table is used to optimize self-interference suppression beamforming.The minimum of the maximum incident power of all receiving elements and the maximum of the transmitting gain pattern are used as optimization objectives, and the single-channel maximum transmitting power and the weight in look-up table are used as constraint conditions to establish the optimization problem of analog beamforming.For the non-convex problem of the optimization problem, the constraint condition of the optimization problem is relaxed in the embodiment of the present application, and the optimization problem is converted into an easy-to-solve form, and then the beamforming weight optimization result satisfying all constraint conditions is solved by using subspace ordering search method.

[0080] With reference to Figure 1 The present application provides a transmitting beamforming method based on engineering analog transceiving simultaneous array, which comprises the following steps:

[0081] S100, measure the attenuator response and phase shifter response of the transmitting array of the transceiving simultaneous array, and construct a transceiving simultaneous array beamforming weight look-up table;

[0082] First of all, it should be pointed out that, as Figure 4To adapt to the high isolation, long distance sensing or communication scene requirements in the transceiving simultaneous array, the application provides a kind of engineering analog transceiving simultaneous array transmitting beam forming implementation method, to reduce the influence of real world analog attenuator and phase shifter error, by optimizing transmitting beam forming, improve the spatial isolation of transmitting array to receiving array in transceiving simultaneous phased array, prevent the saturation of receiving end low noise amplifier and analog-digital converter.The transceiving simultaneous array system is analog array, without reference link architecture.The transmitting radio frequency link includes digital-to-analog converter, up-conversion, power amplifier, power divider, digital attenuator, digital phase shifter, etc.;The receiving link includes low noise amplifier, digital attenuator, digital phase shifter, combiner, down-conversion, power amplifier, analog-digital converter, etc., as shown in Figure 4 The function of digital-to-analog converter is to convert intermediate frequency digital signal into intermediate frequency analog signal.The function of up-conversion is to multiply intermediate frequency analog signal with local oscillator signal, up-convert to transmitting frequency band.The function of power amplifier is to amplify signal power.The function of power divider is to divide transmitting signal into multiple signals with equal power.The function of digital attenuator is to control the amplitude of beam forming weight.The function of digital phase shifter is to control the phase of beam forming weight.The function of low noise amplifier is to amplify receiving signal, while reducing the noise coefficient of receiving link.The function of combiner is to combine multiple receiving signals into one signal.The function of down-conversion is to multiply radio frequency receiving signal with local oscillator signal, down-convert to intermediate frequency.The function of analog-digital converter is to convert intermediate frequency analog signal into intermediate frequency digital signal.

[0083] In Figure 4 , transmitting signal passes through x (n) through digital-to-analog converter, up-conversion, power amplifier, J-way power divider, digital attenuator, digital phase shifter, power amplifier, and then superimposes the Gaussian white noise n t (n) at the end of transmitting antenna to obtain transmitting antenna end signal t (n), after self-interference channel, interference is generated at receiving antenna end, receiving antenna end signal contains self-interference signal and signal of interest s (n), signal passes through low noise amplifier, digital attenuator, digital phase shifter, combiner, down-conversion, power amplifier, analog-digital converter of receiving link, and receiving digital signal y (n) is obtained.

[0084] S110, measure attenuator response and phase shifter response of transmitting array of transceiving simultaneous array;

[0085] Specifically, attenuator response And phase shifter response Is measured by using computer to control vector network analyzer and transmitting component module simultaneously, and measurement schematic diagram is as shown in Figure 5 Attenuator response And phase shifter response Of transceiving simultaneous array transmitting component are measured, and the method comprises the following steps:

[0086] 1) Computer initialization parameter setting;

[0087] 2) Vector network analyzer two ports are connected to the input channel and one of the output channels of the transmitting assembly respectively;

[0088] 3) Use Ethernet to connect the vector network analyzer, and set the measurement parameters;

[0089] 4) Use the serial port to connect the transmitting assembly;

[0090] 5) Computer controls the digital attenuator and digital phase shifter of the transmitting assembly;

[0091] 6) Computer triggers the vector network analyzer to perform sweep frequency measurement through Ethernet;

[0092] 7) After waiting for the vector network analyzer to complete the sweep frequency, save the S parameters to the computer locally;

[0093] 8) Repeat steps 5), 6), and 7) until all digital attenuators and digital phase shifters are measured;

[0094] 9) Replace the output channel of the transmitting assembly, repeat the above measurement operation until all transmitting channels are measured.

[0095] Wherein, the attenuator response of the transceiving simultaneous array transmitting assembly And the phase shifter response Are the S parameters of each attenuator and phase shifter step of each channel of the transmitting assembly, defined as:

[0096]

[0097] In the above formula, is the number of bits of the digital attenuator, is the number of bits of the digital phase shifter, represents the number of transmitting links.

[0098] In some specific embodiments, the number of bits of the digital attenuator is The attenuation interval is 0.5 dB; the number of bits of the digital phase shifter is The phase shift interval is 5.625°, wherein the number of states of the digital attenuator is The number of states of the digital phase shifter is The transmitting channel to be measured is 8, and a total of (64+64) x 8 = 1024 S parameters need to be measured.

[0099] S120, product calculation is performed on the attenuator response and the phase shifter response to construct a transceiving simultaneous array beamforming weight lookup table;

[0100] Specifically, it is considered that the different attenuation and phase shift of the digital attenuator and the digital phase shifter on the same link do not affect each other, and a state element of the transceiving simultaneous array beamforming weight lookup table is equal to the product of the S parameters of the corresponding state of the digital attenuator and the phase shifter.

[0101] Transceiving simultaneous array optional beamforming weight lookup table All possible values defined as analog beamforming weights are three-dimensional complex matrices, that is:

[0102]

[0103] Embodiments of the application consider that the different attenuation and phase shift of the digital attenuator and the digital phase shifter on the same link do not affect each other, and the expression of the transceiving simultaneous array beamforming weight lookup table is specifically as follows:

[0104]

[0105] In the above formula, represents the transceiving simultaneous array optional beamforming weight lookup table, represents the attenuator response of the transceiving simultaneous array transmitting component, represents the phase shifter response of the transceiving simultaneous array transmitting component, N a represents the number of bits of the digital attenuator, N p represents the number of bits of the digital phase shifter, [·] :,j represents the matrix slice, (·) T represents the matrix transpose.

[0106] S200, acquiring an initial transmitting beamforming vector, a steering vector and a maximum single-link transmitting power of a transmitting array of a transceiving simultaneous array, and determining an effective omnidirectional radiation power;

[0107] S210, initializing the transmitting beamforming vector to obtain an initial transmitting beamforming vector;

[0108] S220, determining a desired beam pointing angle, acquiring the steering vector of the transmitting array and the maximum single-link transmitting power;

[0109] S230, determining the effective omnidirectional radiation power according to the desired beam pointing angle, the steering vector of the transmitting array and the initial transmitting beamforming vector.

[0110] The expression of the determination of the effective omnidirectional radiation power is specifically as follows:

[0111]

[0112] In the above formula, φ represents an azimuth angle in a spherical coordinate system, and θ represents a pitch angle in the spherical coordinate system, denotes a transmit beamforming vector, denotes a steering vector of a transmit array, H denotes a conjugate transpose of a matrix, g t denotes a pattern of a transmit array element.

[0113] S300, presetting an inter-antenna coupling matrix of the transceiving simultaneous array, combining an effective isotropic radiated power, an initial transmit beamforming vector and a transceiving simultaneous array beamforming weight lookup table, and constructing an optimization problem;

[0114] S310, presetting an inter-antenna coupling matrix of the transceiving simultaneous array;

[0115] Specifically, a propagation coefficient of a transmit array to a receive array element in the transceiving simultaneous array, a total number of transmit links and a total number of receive links are acquired; and the inter-antenna coupling matrix of the transceiving simultaneous array is preset according to the propagation coefficient, the total number of transmit links and the total number of receive links.

[0116] The expression of the inter-antenna coupling matrix of the transceiving simultaneous array is specifically as follows:

[0117]

[0118] In the above formula, S k,j denotes a propagation coefficient of a transmit array element j to a receive array element k, J and K respectively denote total numbers of transmit and receive links.

[0119] In some specific embodiments, the total numbers of transmit and receive links J = 8, K = 4 in the embodiment of the application, and the size of the ideal transceiving inter-antenna coupling matrix of the transceiving simultaneous array is a complex matrix with 4 rows and 8 columns, that is, The propagation coefficient of each pair of transmit-to-receive in the ideal transceiving inter-antenna coupling matrix of the transceiving simultaneous array in the embodiment of the application is obtained through HFSS simulation.

[0120] S320, determining a self-interference signal power of a receive array element according to the inter-antenna coupling matrix of the transceiving simultaneous array and an initial transmit beamforming vector;

[0121] Specifically, the expression of the determination of the self-interference signal power of the receive array element is specifically as follows:

[0122]

[0123] In the above formula, S denotes a self-interference component power at a receive antenna, denotes an ideal transceiving inter-antenna coupling matrix of the transceiving simultaneous array, Diag(·) denotes a function of taking diagonal elements of a square matrix to form a vector or converting a vector into a diagonal matrix, η t denotes a signal-to-noise ratio of a transmit link.

[0124] S330, determine a transmit array gain pattern according to the effective isotropic radiated power, and set a target function in combination with self-interference signal power of the receiving array elements;

[0125] S340, obtain total transmit power of the transmit array and set a first constraint condition;

[0126] S350, set a second constraint condition according to the transceiving simultaneous array beamforming weight lookup table;

[0127] S360, construct an optimization problem according to the first constraint condition, the second constraint condition and the target function.

[0128] Specifically, the expression of the optimization problem is specifically as follows:

[0129]

[0130] In the above formula, the target function of the optimization problem in formula (1) is to maximize the transmit pattern gain and minimize the self-interference signal power at each receiving array element, and the self-interference power in the denominator is the sum of the self-interference power at each receiving antenna, formula (2) and formula (3) are constraint conditions, formula (2) constrains the transmit power of the transmit link to not exceed the maximum transmit power of the single link, and formula (3) constrains the discrete value range of the analog beamforming weight to be within the lookup table.

[0131] Wherein, the expression of the equivalent self-interference noise covariance matrix is:

[0132]

[0133] In the above formula, P t,m represents the maximum transmit power that a single transmit link can withstand, and |·| 2 represents the square of the complex modulus.

[0134] S400, optimize the initial transmit beamforming vector based on the optimization problem to obtain an optimized target transmit beamforming vector.

[0135] S410, solve the optimization problem by relaxation to remove the constraint condition of the discrete value range of the analog beamforming weight, to obtain a solvable optimization problem;

[0136] S420, perform secondary optimization on the solvable optimization problem to obtain a relaxed optimization problem;

[0137] S430, solve the relaxed optimization problem to obtain an upper bound of the optimization problem and an optimal solution of the transmit beamforming vector;

[0138] Specifically, the optimization problem P1 is solved by relaxation, and the constraint condition of the discrete value range of the analog beamforming weight is removed, to obtain a solvable optimization problem P2, which is expressed as:

[0139]

[0140] The objective function of the optimization problem P2 is in the form of a generalized Rayleigh quotient, which can be maximized, and the optimization problem P2 is further simplified to P3, which is expressed as:

[0141]

[0142] Wherein, γ is a regularization coefficient, which controls the degree of self-interference suppression and the reduction of the transmit pattern gain compared with uniform beamforming.

[0143] Solving the relaxed optimization problem P3, the upper bound of the optimization problem and the optimal solution b of the transmit beamforming vector are obtained t * Then, the subspace ordering search method is used to solve the final solution of the optimization problem satisfying the discrete value constraint of the analog attenuator and phase shifter.

[0144] S440, divide the transceiving simultaneous array beamforming weight lookup table by the optimal solution of the transmit beamforming vector to obtain a division result;

[0145] S450, based on the upper bound of the optimization problem, sort the phase of the division result, and retain the subspace whose error with the optimal solution is within a preset range;

[0146] S460, sort the amplitudes of the subspace, and retain the result closest to the optimal solution as the optimization result, and output the optimized target transmit beamforming vector.

[0147] Specifically, the measured beamforming weight lookup table formed by the analog attenuator and phase shifter is divided by the optimal solution of the transmit beamforming vector; the phase of the division result is sorted, and the subspace whose error with the optimal solution is within a certain range is retained; then the amplitudes of the subspace are sorted, and the result closest to the optimal solution is retained as the optimization result.

[0148] In some specific embodiments, the transmit beamforming weight is defined as:

[0149]

[0150]

[0151] Wherein, P t,m is the maximum transmit power that a single transmit link can withstand, and |·| 2 is the square of the complex modulus.

[0152] Specifically, the dimension of the transmit beamforming vector of the embodiment of the present application is 8x1, and the maximum transmit power of the single transmit chain is 100W.

[0153] Further, the definition of the effective isotropic radiated power (EIRP) of the transmit array is:

[0154] EIRP(φ,θ)=PtGt(φ,θ)

[0155] wherein, P t is the total transmit power of the transmit array; G t is the transmit array gain; φ represents the azimuth angle in the spherical coordinate system; and θ represents the elevation angle in the spherical coordinate system.

[0156] Further, the total transmit power of the embodiment of the present application is:

[0157]

[0158] Therefore, the calculation of the effective isotropic radiated power can be converted to:

[0159]

[0160] wherein, b t is the transmit beamforming weight, (·) H represents the conjugate transpose of the matrix; g t is the directional diagram of the transmit array element, which can be obtained by HFSS simulation. is the steering vector of the transmit array, and its expression is:

[0161]

[0162] wherein, λ is the signal wavelength, x t and y t are the x coordinate and y coordinate of the position of the transmit array element.

[0163] Further, the self-interference power of the receive element of the transceiver simultaneous array is defined to reflect the self-interference isolation performance after beam optimization. The signal flow diagram of the transceiver simultaneous array is given to determine the expression of the incident signal reaching the receive element. The self-interference component power in the expression of the incident signal is calculated.

[0164] wherein, the signal flow diagram of the transceiver simultaneous array of the embodiment of the present application is as shown in Figure 3 , and the expression of the incident signal of the receive element is:

[0165] r(n)=Mb t x(n)+Mn t (n)+s(n)

[0166] where x(n) is the signal to be transmitted, with power 1, i.e., E[|x(n)| 2 ] = 1. n t (n) is the transmit noise, s(n) is the signal of interest at the receive antenna,

[0167] Specifically, by the incident signal expression, the self-interference component power at the receive antenna is

[0168]

[0169] where the self-interference component power at the receive antenna is The function Diag(·) is defined as taking the diagonal elements of a square matrix to form a vector or converting a vector to a diagonal matrix, η t is the signal-to-noise ratio of the transmit link.

[0170] Further, since The self-interference component power at the receive antenna can be rewritten as:

[0171]

[0172] where M bt,k is the equivalent self-interference noise covariance matrix, and the expression is:

[0173]

[0174] where the transmit beamforming vector is optimized, including: determining an optimization objective; determining a constraint condition; establishing an optimization problem model according to the optimization objective and the constraint condition; and solving the optimization problem.

[0175] Specifically, the optimization objective is determined to maximize the gain of the transmit direction pattern of interest while minimizing the self-interference signal power of each receive antenna, and the expression of the optimization objective can be written as:

[0176]

[0177] The constraint condition is determined, including: taking the maximum transmit power that a single transmit link can withstand as constraint condition 1; and taking the beamforming weight that can only take values in the lookup table as constraint condition 2,

[0178] where the maximum transmit power that a single transmit link can withstand as constraint condition 1 can be written as:

[0179] |b t,j | 2 ≤ P t,m , j = 1, 2,..., J

[0180] where constraint 2 is that the beamforming weight can only take values in the look-up table, which can be written as:

[0181]

[0182] Specifically, according to the optimization objective and the constraint conditions, an optimization problem model is established, i.e.:

[0183]

[0184] where the first line is the objective function of the optimization problem, which is to maximize the transmit pattern gain and minimize the self-interference signal power at each receiving array element, and the denominator is the sum of the self-interference power at each receiving antenna; the second and third lines are constraint conditions, the second line restricts the transmit power of the transmit link to not exceed the maximum transmit power of the single link, and the third line restricts the discrete value range of the analog beamforming weight to be within the look-up table.

[0185] However, the optimization problem P1 is a non-convex problem difficult to solve because the value of the decision variable is discrete. Therefore, the optimization problem P1 is solved by relaxation, and the constraint condition of the discrete value range of the analog beamforming weight is removed to obtain a solvable optimization problem P2:

[0186]

[0187] s.t. |b t,j | 2 ≤P t,m j = 1, 2,..., J

[0188] Since the objective function of the optimization problem P2 is the generalized Rayleigh quotient of b t , this quotient can be maximized, and the optimization problem P2 can be further simplified as:

[0189]

[0190] where γ is a regularization coefficient, which controls the degree of self-interference suppression and the degree of reduction of the transmit pattern gain. When γ is large, the degree of self-interference suppression is low, and the degree of reduction of the transmit pattern gain compared with uniform beamforming is also low; when γ is small, the degree of self-interference suppression is large, and the degree of reduction of the transmit pattern gain compared with uniform beamforming is also large.

[0191] Further, the relaxed optimization problem P3 is solved to obtain the upper bound of the optimization problem and the optimal solution b t *Then, the subspace sorting search method is used to solve the final solution of the optimization problem that satisfies the discrete value constraints of the simulated attenuator and phase shifter. The process of the subspace sorting search method is as follows: the measured beamforming weights formed by the simulated attenuator and phase shifter are used to look up the table. The beamforming weights are divided by the optimal solution of the transmitted beamforming vector. The phases of the division results are then sorted, retaining subspaces where the phase error with the optimal solution is within a certain range. The amplitudes of these subspaces are then sorted, and the result closest to the optimal solution is retained as the optimized result. Since the phase of the beamforming weights significantly affects self-interference suppression and the synthetic pattern gain, the sorting search method first limits the phase error and then sorts the amplitudes, ensuring that the phase error does not exceed a certain value.

[0192] Furthermore, the optimized beamforming vector is multiplied by the steering vector to construct the transmit beam in the target direction. Based on the optimized beamforming vector, the self-interference signal power before and after beam optimization is calculated using the self-interference component power expression.

[0193] like Figure 6 as well as Figure 7 As shown, to control the amplitude and phase of S21 of the transmission channel under different attenuation values ​​of the digitally controlled attenuator, taking transmission channel 1 as an example, port 1 of the vector network analyzer is connected to the input of the 8-way power divider of the transmission component 1, and port 2 is connected to the output of the power divider, digitally controlled phase shifter, digitally controlled attenuator and power amplifier. Figure 6 The display shows the S21 amplitude of the transmission channel under different attenuation values ​​of the digitally controlled attenuator. It can be seen that the S21 amplitude of the attenuator gradually decreases with control, and the attenuation control interval is about 0.5dB. However, the actual attenuation interval of the attenuator has errors, with some intervals being greater than 0.5dB and some intervals being less than 0.5dB. Figure 7 The S21 phase of the transmit channel is shown when the digitally controlled attenuator has different attenuation values. It can be seen that in some frequency bands, such as 12-18GHz, the additional phase of the attenuator varies greatly under different attenuation values.

[0194] like Figure 8 as well as Figure 9 The figure shows the phase and amplitude of S21 in the transmit channel when the numerically controlled phase shifter is set to different phase shift values. Experimental setup and... Figure 6 as well as Figure 7 same. Figure 8 The display shows the S21 phase of the transmission channel under different phase shift values ​​of the CNC phase shifter. It can be seen that the S21 phase of the phase shifter gradually moves with the control. The theoretical phase shift control interval is about 5.625°, but the actual phase shift interval error is large. Figure 9The display shows the S21 amplitude of the transmit channel with different phase shift values ​​for the digitally controlled phase shifter. It can be seen that at certain frequency points, the additional attenuation of the phase shifter differs with different phase shift values, with a difference of approximately 1 dB. (Summary) Figure 6 , Figure 7 , Figure 8 as well as Figure 9 The experiment shows that due to the imperfections in the characteristics of actual attenuators and phase shifters, the weight control of simulated beamforming is easily affected.

[0195] like Figure 10 as well as Figure 11 The image shows the response of the automatically measured attenuator. and phase shifter response The attenuation and phase shift lookup table for the 7GHz transmit channel 1 was subsequently generated. Based on the actual measured lookup table, the optimized beamforming weights were generated, taking into account the imperfections of the actual numerically controlled attenuators and phase shifters, as well as the amplitude and phase inconsistencies between channels (when both the attenuator and phase shifter are at 0, the measured response is the inherent response of the channel), making the simulated beamforming self-interference suppression more practical.

[0196] like Figure 12 as well as Figure 13 As shown, Figure 12 The maximum self-interference of all receiving antennas in all beam directions at different operating frequencies. Figure 13 The beam patterns at -5° for different operating frequencies were compared with uniform beamforming, traditional analog beamforming methods that directly quantize without considering actual attenuation phase shifter characteristics, and the method of this invention. Simulations were performed at frequencies of 6 GHz, 7 GHz, 9 GHz, 15 GHz, and 18 GHz. The results show that the method of this invention considers the actual attenuation phase shifter characteristics. Compared with uniform beamforming, the maximum self-interference of all receiving antennas in all beam directions at different operating frequencies is reduced most at 6 GHz (26.12 dB) and least at 18 GHz (19 dB). Compared with the traditional directly quantized analog beamforming method, the self-interference power at 7 GHz remains basically the same, while the self-interference power at other frequencies is reduced, with the largest reduction at 18 GHz (6.61 dB). The method presented in this paper has a transmit pattern gain that is basically consistent with that of traditional analog beamforming methods. Compared with uniform beamforming, the transmit pattern gain is reduced by about 5dB. This is because in the beamforming self-interference suppression algorithm, self-interference power and transmit pattern are a pair of contradictory quantities. When the degree of self-interference suppression is large, the transmit pattern gain will inevitably decrease.

[0197] Figure 14 The standard deviation of the actual attenuator and phase shifter characteristics at different operating frequencies. Figure 14(a) is the maximum phase standard deviation of the attenuator under all attenuation phase shift control conditions of all transmission channels at different operating frequencies, Figure 14 (b) is the maximum phase standard deviation of the phase shifter under all attenuation phase shift control conditions of all transmission channels at different operating frequencies, Figure 14 (c) is the maximum amplitude standard deviation of the attenuator under all attenuation phase shift control conditions of all transmission channels at different operating frequencies, Figure 14 (d) is the maximum amplitude standard deviation of the phase shifter under all attenuation phase shift control conditions of all transmission channels at different operating frequencies. This result to some extent explains Figure 12 and Figure 13 the results in (a), (b), (c) and (d), the standard deviation of the attenuator phase shifter characteristics is smaller when the operating frequency is 7GHz, indicating that the actual characteristics of the attenuator phase shifter are close to the ideal case, and at this time the method in this paper has no improvement compared with the traditional method. However, when the standard deviation of the attenuator phase shifter characteristics is larger, it indicates that the actual characteristics of the attenuator phase shifter deviate greatly from the ideal case, and the method of the present application has obvious improvement compared with the traditional method.

[0198] Finally, as shown in Figure 15 , the measured results of self-interference suppression beamforming are shown, the uniform beamforming (CBF) at 7GHz frequency and the beam pointing at 0, and the self-interference signal power of each receiving antenna of the method proposed in this paper are measured. The experimental results show that the beamforming method proposed in this paper effectively realizes the self-interference suppression, and in the experiment the largest reduction of self-interference signal power is obtained at antenna 1, which is reduced by 19.2dB, and the worst suppression case is receiving antenna 2, which is reduced by 14.44dB.

[0199] In summary, as shown in Figure 3 , the method for implementing the transmission beamforming of the engineered analog transmit-receive simultaneous array provided by the embodiment of the present application comprises: determining the configuration parameters of the transmit-receive simultaneous array system, wherein the configuration parameters of the transmit-receive simultaneous array are determined, including: determining the number of transmit-receive links of the transmit-receive simultaneous array system; determining the distribution shape parameter of the transmit-receive simultaneous array; determining the element spacing parameter of the transmit-receive simultaneous array; determining the scanning range of the main beam of the transmit-receive simultaneous array system; determining the center frequency at which the transmit-receive simultaneous array system works; the transmit-receive simultaneous array is an 8-transmit-4-receive uniform linear array, and the elements adopt coaxial feed spiral antennas.

[0200] further define the ideal transmit-receive antenna coupling matrix M of the transmit-receive simultaneous array; define the attenuator response and the phase shifter response of the transmit-receive simultaneous array beamforming component define the transmit beamforming weight b under the transmit-receive simultaneous arrayt , define the effective isotropic radiated power of the transmit array to reflect the transmit pattern after beam optimization; define the self-interference power of the receive array of the transceiving simultaneous array to reflect the self-interference isolation performance after beam optimization; optimize the transmit beamforming vector; construct the transmit beam in the target direction according to the optimized beamforming vector. According to the optimized beamforming vector, the self-interference signal power before and after beam optimization is calculated.

[0201] Referring to Figure 2 , the transmit beamforming system based on the engineered transceiving simultaneous array includes:

[0202] The first module 201 is configured to measure the attenuator response and the phase shifter response of the transmit array of the transceiving simultaneous array, and construct a transceiving simultaneous array beamforming weight lookup table;

[0203] The second module 202 is configured to obtain the initial transmit beamforming vector, the steering vector and the maximum single-link transmit power of the transmit array of the transceiving simultaneous array, and determine the effective isotropic radiated power;

[0204] The third module 203 is configured to pre-set the inter-antenna coupling matrix of the transceiving simultaneous array, combine the initial transmit beamforming vector with the transceiving simultaneous array beamforming weight lookup table, and construct an optimization problem;

[0205] The fourth module 204 is configured to optimize the initial transmit beamforming vector based on the optimization problem to obtain the optimized target transmit beamforming vector.

[0206] The contents in the above method embodiments are all applicable to the system embodiments, the system embodiments specifically implement the same functions as the above method embodiments, and achieve the same beneficial effects as the above method embodiments.

[0207] The above is a specific description of the preferred embodiments of the present application, but the present application is not limited to the above-mentioned embodiments. Those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the present application. These equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A transmit beamforming method based on an engineered analog transmit-receive simultaneous array, characterized in that, The method comprises the following steps: measuring the digital attenuator response and the digital phase shifter response of the transmitting array of the transceiving simultaneous array; performing product calculation on the digital attenuator response and the digital phase shifter response to construct a transceiving simultaneous array beamforming weight lookup matrix; the expression of the transceiving simultaneous array beamforming weight lookup matrix is specifically as follows: ； In the above formula, denotes a transceiver simultaneous array beamforming weight lookup matrix, denotes a digitally controlled attenuator response of a transceiver simultaneous array transmit element, denotes a digitally controlled phase shifter response of a transceiver simultaneous array transmit element, denotes the number of bits of a digitally controlled attenuator, denotes the number of bits of a digitally controlled phase shifter, denotes a matrix slice, denotes a matrix transpose; obtaining the initial transmitting beamforming vector, the steering vector and the maximum single-link transmitting power of the transmitting array of the transceiving simultaneous array, and determining the effective isotropic radiated power; pre-setting the inter-antenna coupling matrix of the transceiving simultaneous array; determining the self-interference signal power of the receiving array element according to the inter-antenna coupling matrix of the transceiving simultaneous array and the initial transmitting beamforming vector; determining the transmitting array gain pattern according to the effective isotropic radiated power, and setting a target function in combination with the self-interference signal power of the receiving array element; obtaining the total transmitting power of the transmitting array and setting a first constraint condition; setting a second constraint condition according to the transceiving simultaneous array beamforming weight lookup matrix; constructing an optimization problem according to the first constraint condition, the second constraint condition and the target function; optimizing the initial transmitting beamforming vector based on the optimization problem to obtain an optimized target transmitting beamforming vector.

2. The method of claim 1, wherein, The step of obtaining the initial transmitting beamforming vector, the steering vector and the maximum single-link transmitting power of the transmitting array of the transceiving simultaneous array, and determining the effective isotropic radiated power specifically comprises: initializing the transmitting beamforming vector to obtain the initial transmitting beamforming vector; determining the expected beam pointing angle, obtaining the steering vector and the maximum single-link transmitting power of the transmitting array; determining the effective isotropic radiated power according to the expected beam pointing angle, the steering vector of the transmitting array and the initial transmitting beamforming vector.

3. The method of claim 2, wherein, The expression of the effective isotropic radiated power is specifically as follows: ； In the above formula, Represents the azimuth angle in a spherical coordinate system. Represents the pitch angle in a spherical coordinate system. Indicates the transmitted beamforming vector. This represents the steering vector of the transmitting array. Represents the conjugate transpose of a matrix. This indicates the radiation pattern of the transmitting array element.

4. The method of claim 3, wherein, The step of pre-setting the inter-antenna coupling matrix of the transceiving simultaneous array specifically comprises: obtaining the propagation coefficient from the transmitting array to the receiving array element in the transceiving simultaneous array, the total transmitting link number and the total receiving link number; pre-setting the inter-antenna coupling matrix of the transceiving simultaneous array according to the propagation coefficient, the total transmitting link number and the total receiving link number; The expression of the inter-antenna coupling matrix of the transceiving simultaneous array is specifically as follows: ； In the above formula, denotes the propagation coefficient from the transmit array element to the receive array element , and denote the total number of transmit and receive links, respectively.

5. The method of claim 4, wherein, The expression of the self-interference signal power of the receiving array element is specifically as follows: ； In the above formula, denotes the self-interference component power at the receive antenna, denotes the inter-antenna coupling matrix of the transceiving simultaneous array, denotes a function that forms a vector from the diagonal elements of a square matrix or converts a vector into a diagonal matrix, denotes the signal-to-noise ratio of the transmission link.

6. The method of claim 5, wherein, The expression of the optimization problem is specifically as follows: ； In the above formula, formula is the objective function of the optimization problem, is to maximize the transmit pattern gain and minimize the self-interference signal power at each receiving element, the denominator of the self-interference power is the sum of the self-interference power at each receiving antenna, formula and formula are constraint conditions, formula constrains the transmit power of the transmit link to not exceed the maximum transmit power of the single link, formula constrains the discrete value range of the analog beamforming weight to be within the lookup matrix.

7. The method of claim 6, wherein, The step of optimizing the initial transmitting beamforming vector based on the optimization problem to obtain an optimized target transmitting beamforming vector specifically comprises: performing relaxation solution on the optimization problem to remove the constraint condition of the discrete value range of the analog beamforming weight, to obtain a solvable optimization problem; performing secondary optimization on the solvable optimization problem to obtain a relaxed optimization problem; solving the relaxed optimization problem to obtain the upper bound value of the optimization problem and the optimal solution of the transmitting beamforming vector; performing division calculation on the transceiving simultaneous array beamforming weight lookup matrix and the optimal solution of the transmitting beamforming vector to obtain a division result; based on the upper bound value of the optimization problem, sorting the phase of the division result, and retaining the subspace in which the error between the phase and the optimal solution is within a preset range; The amplitudes of the subspaces are sorted, and the result closest to the optimal solution in amplitude is retained as the optimized result, and the optimized target transmit beamforming vector is output.

8. A transmit beamforming system based on an engineered analog transceiving simultaneous array, characterized in that, The method comprises the following modules: A first module is configured to measure the responses of digital attenuators and digital phase shifters of a transmit array of a transceiver simultaneous array; The responses of the digital attenuators and the digital phase shifters are multiplied to construct a beamforming weight lookup matrix of the transceiver simultaneous array; The expression of the beamforming weight lookup matrix is specifically as follows: ； In the above formula, denotes a transceive-simultaneous array beamforming weight lookup matrix, denotes a digital attenuator response of a transceive-simultaneous array transmit element, denotes a digital phase shifter response of a transceive-simultaneous array transmit element, denotes the number of bits of a digital attenuator, denotes the number of bits of a digital phase shifter, denotes a matrix slice, denotes a matrix transpose; A second module is configured to obtain an initial transmit beamforming vector, a steering vector and a maximum single-link transmit power of the transmit array of the transceiver simultaneous array, and determine an effective isotropic radiated power; A third module is configured to preset an inter-antenna coupling matrix of the transceiver simultaneous array; According to the inter-antenna coupling matrix and the initial transmit beamforming vector, the self-interference signal power of a receiving array element is determined; According to the effective isotropic radiated power, a transmit array gain pattern is determined, and in combination with the self-interference signal power of the receiving array element, a target function is set; The total transmit power of the transmit array is obtained, and a first constraint condition is set; According to the beamforming weight lookup matrix, a second constraint condition is set; According to the first constraint condition, the second constraint condition and the target function, an optimization problem is constructed; A fourth module is configured to optimize the initial transmit beamforming vector based on the optimization problem, and obtain an optimized target transmit beamforming vector.

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