Coupling matrix self-measurement method of array capable of receiving and transmitting simultaneously

Abstract

The invention discloses a coupling matrix self-measurement method of a receiving and transmitting simultaneous array. The method comprises the following steps: acquiring a theoretical antenna coupling matrix of the receiving and transmitting simultaneous array through simulation; transmitting and receiving array amplitude-phase errors of the transmitting and receiving simultaneous array are measured and stored; according to a transmitting signal and a receiving signal of the simultaneous receiving and transmitting array, a theoretical antenna coupling matrix is received, an attenuation value required for closing other transmitting channels when the signal is transmitted independently is determined, and a receiving signal power range is determined; carrying out dynamic conversion on the transmitting and receiving configuration and the receiving gain of the transmitting and receiving simultaneous array to enable the receiving signal power to be within the receiving signal power range; and measuring a coupling channel under each transmitting and receiving configuration of the transmitting and receiving simultaneous array to obtain a coupling matrix. According to the invention, self-interference channel estimation of a large-scale phased array system capable of receiving and transmitting simultaneously is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of simultaneous transceiver array coupling matrix measurement, and more specifically, to a method for self-measuring the coupling matrix of a simultaneous transceiver array. Background Art

[0002] With the rapid development of wireless communication technology, the demand for spectrum resources has increased sharply, and how to more efficiently utilize limited spectrum resources has become an urgent problem to be solved.

[0003] The simultaneous transceiver technology, also known as in-band full-duplex technology, can simultaneously transmit and receive on the same frequency band, doubling the spectrum utilization rate and greatly alleviating the pressure of spectrum resource shortage. The biggest challenge faced by the simultaneous transceiver technology is the strong self-interference generated by the transmitted signal to the received signal. These self-interference signals will saturate the receiving end and submerge the signal of interest.

[0004] With the development of technology, the existing research on self-interference signal suppression focuses on three aspects: the propagation domain, the analog domain, and the digital domain. However, compared with the digital domain method, the isolation achieved by the antenna and the analog domain method is limited. Especially in a large-scale phased array with strong multi-dimensional cross-coupling SI from the transmitter to the receiver, radio frequency cancellation will bring huge costs to the system in terms of size, complexity, and power consumption.

[0005] Beamforming is an effective technology that can improve the isolation of the STAR phased array in the spatial domain. A large number of studies have proposed various algorithms for different types of arrays, effectively achieving the isolation of self-interference signals in the spatial domain. The self-interference coupling matrix describes the self-interference channel between the transmitting antenna and the receiving antenna and is an important parameter for beamforming.

[0006] Existing beamforming methods applied to simultaneous transceiver array systems all require the coupling channel information from the transmitting antenna to the receiving antenna. However, the research on coupling channel estimation is usually used for digital and analog cancellation, without distinguishing the coupling channels of different transmitting antennas, and less attention has been paid to the estimation of the coupling matrix between multiple transmitting and receiving antennas for beamforming self-interference suppression.

[0007] There are three ways to obtain the coupling matrix in the existing research on adaptive beamforming:

[0008] One is to use HFSS or near-field radiation model to simulate the theoretical value of antenna array coupling. The disadvantage is that it is too idealized and does not consider the complex and time-varying channel environment in actual applications.

[0009] The second is to measure using a vector network analyzer in engineering. This measurement method has a large workload, lacks flexibility for system design iteration and environmental changes, is prone to introducing errors when disconnecting the antenna and connecting the vector network analyzer, and it is difficult to form a fixed system for simultaneous transceiver phased arrays.

[0010] Thirdly, there are traditional channel estimation algorithms. These algorithms are usually applied to wireless communication channel scenarios and are significantly different from self-interference channel estimation in terms of reference source, data volume, signal-to-noise ratio, timeliness, etc. At the same time, large-scale analog phased arrays cannot allocate different pilot sequences to each transmit channel, so they are not suitable for channel estimation methods based on pilot sequences.

[0011] Existing research on the estimation of the coupling matrix between transmit and receive antennas usually requires couplers to couple the transmit and receive signals for channel estimation, which is not applicable to the simultaneous transmit and receive systems without coupling links. Summary of the Invention

[0012] The present invention provides a method for self-measuring the coupling matrix of a simultaneous transmit and receive array, which solves the technical problems in the beamforming method of the simultaneous transmit and receive array system in the prior art, such as inaccurate measurement of the coupling matrix, large workload, and unsuitability for using traditional channel estimation algorithms in the application scenario.

[0013] To solve the above technical problems, the technical solution of the present invention is as follows:

[0014] The present invention provides a method for self-measuring the coupling matrix of a simultaneous transmit and receive array, including the following steps:

[0015] Obtain the theoretical antenna coupling matrix of the simultaneous transmit and receive array through simulation;

[0016] Measure and store the amplitude and phase errors of the transmit and receive arrays of the simultaneous transmit and receive array;

[0017] According to the transmit signal, receive signal, and theoretical antenna coupling matrix of the simultaneous transmit and receive array, determine the attenuation value required to turn off the remaining transmit channels when transmitting a single transmit signal, and determine the receive signal power range;

[0018] Dynamically transform the transmit and receive configuration and receive gain of the simultaneous transmit and receive array so that the receive signal power is within the receive signal power range;

[0019] Measure the coupling channels under each transmit and receive configuration of the simultaneous transmit and receive array to obtain the coupling matrix.

[0020] In the above technical means, by controlling the array transmit antennas to transmit in sequence and the receive antennas to receive in sequence, adaptively adjusting the receive power, using the methods of least squares channel estimation and recursive least squares channel estimation to estimate the coupling matrix between the transmit antenna and the receive antenna, and then performing adaptive beamforming and digital cancellation to suppress self-interference signals, so as to improve the isolation of the simultaneous transmit and receive array.

[0021] Further, the obtaining the theoretical antenna coupling matrix of the simultaneous transmit and receive array through simulation includes:

[0022] The theoretical antenna coupling matrix of the transmit-receive simultaneous array is a complex matrix of J×K, where the element in the j-th row and k-th column is defined as the propagation coefficient from the j-th transmit antenna to the k-th receive antenna, and J and K are the total numbers of transmit antennas and receive antennas respectively;

[0023] The theoretical antenna coupling matrix of the transmit-receive simultaneous array is obtained through HFSS simulation.

[0024] Furthermore, the amplitude-phase error of the transmit-receive array includes the transmit amplitude and phase error Γ t and the receive amplitude and phase error Γ r , where the transmit amplitude and phase error Γ t is the propagation coefficient from the digital-to-analog converter at the transmit link to the antenna end when the transmit link gain and beamforming weight of the transmit-receive simultaneous array are equal, and the receive amplitude and phase error Γ r is the propagation coefficient from the analog-to-digital converter at the receive link to the antenna end when the receive link gain and beamforming weight of the transmit-receive simultaneous array are equal.

[0025] Furthermore, measuring and storing the amplitude-phase error of the transmit-receive array of the transmit-receive simultaneous array includes:

[0026] Measuring and storing the amplitude-phase error of the transmit-receive array of the transmit-receive simultaneous array through a vector network analyzer or near-field measurement.

[0027] Furthermore, according to the transmit signal, receive signal, and theoretical antenna coupling matrix of the transmit-receive simultaneous array, determining the attenuation value required to turn off the remaining transmit channels when transmitting a single transmit signal and determining the receive signal power range includes:

[0028] Defining the attenuation value S when the antenna switch filter of the transmit-receive simultaneous array is turned off as the attenuation value required for a certain antenna of the transmit array to transmit alone while the remaining transmit channels are turned off;

[0029] Traversing different attenuation values S of the antennas of the transmit-receive simultaneous array;

[0030] For each attenuation value S, let one transmit channel transmit, apply this attenuation value S to the remaining turned-off transmit channels, and use Monte Carlo simulation to simulate the influence of the random phase shift existing in the remaining turned-off transmit channels on the coupling self-interference at the analog-to-digital converter at the receive antenna;

[0031] Selecting the attenuation value S with less influence;

[0032] Confirming whether there is a hardware configuration in the transmit link of the transmit-receive simultaneous array that can reach the above attenuation value;

[0033] If there is, obtaining the receive signal power range corresponding to the attenuation value S with less influence.

[0034] Further, use Monte Carlo simulation to study the influence of random phase shifts in the remaining closed transmit channels on the coupled self-interference at the receiving antenna, including:

[0035] Evaluate the influence of random phase shifts in the remaining closed transmit channels on the coupled self-interference at the receiving antenna using relative mean square error, where the relative mean square error is defined as the ratio of the mean square error of channel estimation to the square of the amplitude of the channel estimation result.

[0036] Further, obtain the range of received signal power corresponding to the attenuation value S with less influence, including:

[0037]

[0038] In the formula, P kj is the received signal power when the j-th antenna transmits alone and the k-th antenna receives alone, V ref is the reference voltage of the analog-to-digital converter in the receiving link of the simultaneous transmit and receive array, and P min is the minimum received signal power that ensures a relatively small mean square error in the coupled self-interference channel estimation and is not affected by quantization error.

[0039] Further, dynamically transform the transmit and receive configuration and receive gain of the simultaneous transmit and receive array so that the received signal power is within the range of the received signal power, including:

[0040] Control the transmit antennas of the simultaneous transmit and receive array to transmit alone in sequence, and the receive antennas of the simultaneous transmit and receive array to receive alone in sequence;

[0041] Control the receive gain of the receive antennas of the simultaneous transmit and receive array so that the received signal power is within the range of the received signal power;

[0042] Save the transmit signal, receive signal, and receive gain for each configuration.

[0043] Further, control the receive gain of the receive antennas of the simultaneous transmit and receive array so that the received signal power is within the range of the received signal power, including:

[0044] Calculate the received signal power;

[0045] If the received signal power is less than the minimum received signal power, increase the receive gain:

[0046] G kj (m + 1) = G kj (m) + Δ G , P kj ≤P min

[0047] If the received signal power is greater than the maximum received signal power, decrease the receive gain:

[0048]

[0049] where m is the number of iterations for adjusting the receiving gain, G kj (m) is the receiving gain at the m-th iteration, and ΔG is the adjustment step size of the receiving gain, with the unit of dB;

[0050] If the received signal power is within the received signal power range, end the loop, calculate the difference between the current receiving gain and the initial receiving gain, and construct the transmit power difference matrix G Δ,dB .

[0051] Furthermore, measure the coupling channels for each transceiver configuration of the simultaneous transceiver array to obtain the coupling matrix:

[0052] Adopt the least squares channel estimation method to obtain the self-interference channel estimation between antennas as:

[0053]

[0054] where represents the self-interference channel between the j-th transmit antenna and the k-th receive antenna obtained by using the least squares channel estimation method, and Y kj (e jω ), X kj (e jω ) respectively represent the Fourier transforms of the received signal and the transmitted signal, Γ tj represents the transmit amplitude and phase error of the j-th transmit antenna, Γ rk represents the receive amplitude and phase error of the k-th receive antenna, and G Δ,kj is the receive gain adjustment difference when the antenna j transmits alone and the antenna k receives alone, and the unit is converted from dB to 1;

[0055] Construct the estimated coupling matrix:

[0056]

[0057] where is the coupling matrix estimated by using the least squares channel estimation method;

[0058] Adopt the recursive least squares channel estimation method to obtain the self-interference channel estimation between antennas as:

[0059]

[0060] where represents the self-interference channel between the j-th transmit antenna and the k-th receive antenna obtained by using the recursive least squares channel estimation method, N is the filter length, and wkj,i is the i-th weight after the convergence of the recursive least squares algorithm, where i = 1, ..., N - 1, Γ tj represents the transmission amplitude and phase error of the j-th transmitting antenna, Γ rk represents the reception amplitude and phase error of the k-th receiving antenna, G Δ,kj is the difference in reception gain adjustment when antenna j transmits alone and antenna k receives alone, with the unit converted from dB to 1;

[0061] Construct an estimated coupling matrix:

[0062]

[0063] In the formula, is the coupling matrix estimated by using the recursive least squares channel estimation method.

[0064] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0065] 1. The present invention is conducive to engineering implementation, can adapt to complex time-varying self-interference channel environments, realizes in-board measurement of the coupling matrix, and is conducive to the actual engineering implementation of simultaneous transmit and receive phased arrays;

[0066] 2. The present invention is applicable to analog and digital simultaneous transmit and receive array systems with or without cancellation architectures, and can effectively improve the transmit and receive isolation of the system;

[0067] 3. The present invention estimates the coupling matrix through the transmit and receive signals of the transmit and receive antennas transmitting and receiving alone, reduces the computational complexity of matrix inversion and the estimation of multiple intermediate variables and error accumulation in the prior art, and realizes fast and accurate estimation of the coupling matrix between the transmit and receive antennas of a simultaneous transmit and receive phased array. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 is a schematic flowchart of a method for self-measuring the coupling matrix of a simultaneous transmit and receive array provided by an embodiment of the present invention;

[0069] Figure 2 is a schematic structural diagram of a simultaneous transmit and receive array provided by an embodiment of the present invention;

[0070] Figure 3 is a schematic diagram of the array antenna layout of a simultaneous transmit and receive array provided by an embodiment of the present invention;

[0071] Figure 4 is a schematic flowchart of the algorithm provided by an embodiment of the present invention;

[0072] Figure 5 is a schematic diagram showing the influence of the attenuation value of the closed-channel switch filter on the coupling error provided by an embodiment of the present invention;

[0073] Figure 6 Schematic diagram showing the influence of the relative mean square error of channel estimation provided by an embodiment of the present invention on the number of ADC bits occupied by the received signal

[0074] Figure 7 Schematic diagram showing the amplitude and phase of the coupling matrix estimated by using the LS and RLS methods provided by an embodiment of the present invention

[0075] Figure 8 Schematic diagram showing the amplitude and phase of the estimation error between the coupling matrix estimated by using the LS and RLS methods and the true value of the coupling matrix provided by an embodiment of the present invention

[0076] Figure 9 Schematic diagram showing the self-interference signal power and effective isotropic isolation degree at different scanning angles provided by an embodiment of the present invention Detailed implementation manners

[0077] The accompanying drawings are only for illustrative purposes and should not be construed as a limitation of this patent.

[0078] To better illustrate this embodiment, some components in the accompanying drawings are omitted, enlarged or reduced, which do not represent the dimensions of the actual product.

[0079] For those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0080] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0081] Embodiment 1

[0082] This embodiment provides a self-measurement method for the coupling matrix of a simultaneous transceiver array, as shown in Figure 1 and Figure 4 , and includes the following steps:

[0083] Obtain the theoretical antenna coupling matrix of the simultaneous transceiver array through simulation;

[0084] Measure and store the amplitude-phase error of the transmit-receive array of the simultaneous transceiver array;

[0085] According to the transmit signal, receive signal and theoretical antenna coupling matrix of the simultaneous transceiver array, determine the attenuation value required to turn off the remaining transmit channels when transmitting a single signal, and determine the receive signal power range;

[0086] Dynamically transform the transmit-receive configuration and receive gain of the simultaneous transceiver array so that the receive signal power is within the receive signal power range;

[0087] Measure the coupling channels in each transmit-receive configuration of the simultaneous transceiver array to obtain the coupling matrix.

[0088] Embodiment 2

[0089] Based on Embodiment 1, this embodiment further describes the self-measurement method of the coupling matrix of the simultaneous transceiver array.

[0090] The simultaneous transceiver array system described in this embodiment is an analog array without a reference link architecture. The transmitting RF link includes a DAC, a mixer, a power amplifier, a power splitter, a digital controlled attenuator, a digital controlled phase shifter, etc.; the receiving link includes receiving components such as a low noise amplifier, a filter, a mixer, and an ADC, as Figure 2 shown.

[0091] In a further embodiment, it also includes determining the configuration parameters of the simultaneous transceiver array, including:

[0092] Determining the number of transmitting and receiving antennas of the simultaneous transceiver array system;

[0093] Determining the receiving gain of the simultaneous transceiver array;

[0094] Determining the center frequency at which the simultaneous transceiver array system operates.

[0095] In a further embodiment, the obtaining of the theoretical antenna coupling matrix of the simultaneous transceiver array through simulation includes:

[0096] The theoretical antenna coupling matrix of the simultaneous transceiver array is a complex matrix of J×K, where the element in the j-th row and k-th column is defined as the propagation coefficient from the j-th transmitting antenna to the k-th receiving antenna, and J and K are the total numbers of transmitting and receiving antennas respectively;

[0097] In this embodiment, the simultaneous transceiver array is an 8-transmit 4-receive uniform linear array, and the array elements use coaxial-fed helical antennas. Among them, the upper left 1×8 array is the transmitting array, and the lower right 1×4 array is the receiving array, as Figure 3 shown; the number of transmitting and receiving links J = 8 and K = 4 in the embodiment of the present invention, then the scale of the ideal mutual coupling matrix between the transmitting and receiving antennas of the simultaneous transceiver array is a 4-row 8-column complex matrix, that is

[0098] M∈C 4×8

[0099] The theoretical antenna coupling matrix of the simultaneous transceiver array is obtained through HFSS simulation;

[0100] In a further embodiment, the amplitude and phase errors of the transmitting and receiving arrays include the transmitting amplitude and phase error Γ t and the receiving amplitude and phase error Γ r [ , where the transmitting amplitude and phase error Γ tis the propagation coefficient from the digital-to-analog converter at the transmit link to the antenna end when the transmit link gain and beamforming weights of the transmit-receive simultaneous array are equal, and the receive amplitude and phase error Γ r is the propagation coefficient from the analog-to-digital converter at the receive link to the antenna end when the receive link gain and beamforming weights of the transmit-receive simultaneous array are equal.

[0101] In this embodiment, the number of transmit and receive links J = 8, K = 4, then the transmit-receive amplitude and phase errors of the transmit-receive simultaneous array are column vectors of length 8 and 4 respectively, that is

[0102] Γ t ∈C 8×1

[0103] Γ r ∈C 4×1

[0104] In a further embodiment, measuring and storing the transmit-receive array amplitude-phase error of the transmit-receive simultaneous array includes:

[0105] Measuring and storing the transmit-receive array amplitude-phase error of the transmit-receive simultaneous array through a vector network analyzer measurement or near-field measurement.

[0106] In a further embodiment, the present invention embodiment also defines the transmit-receive system mutual coupling matrix of the transmit-receive simultaneous array To distinguish it from the antenna-to-antenna coupling matrix, the transmit-receive system mutual coupling matrix of the transmit-receive simultaneous array is defined as the coupling matrix between the transmit DAC and the receive ADC of the transmit-receive simultaneous array; the scale of the transmit-receive system mutual coupling matrix of the transmit-receive simultaneous array is a 4-row 8-column complex matrix, that is

[0107]

[0108] where, diag(·) is a function that converts a vector into a diagonal matrix, and H represents the conjugate transpose of the matrix;

[0109] In this embodiment, the entire RF system is used to measure the coupling matrix, so a system-level coupling matrix is defined, which describes the difference between the coupling matrix measured using the RF system and the required antenna-to-antenna coupling matrix, with the influence of channel errors. The system coupling matrix directly estimated from the transmit and receive signals needs to subtract the channel errors on the basis of the system-level coupling matrix to obtain the antenna-to-antenna coupling matrix, that is, the final required result.

[0110] In a further embodiment, according to the transmit signal and receive signal of the transmit-receive simultaneous array and the theoretical antenna coupling matrix, determining the attenuation value required to turn off the remaining transmit channels when transmitting a single transmit signal, and determining the received signal power range, includes:

[0111] Define the attenuation value S when the transceiver simultaneous array antenna switch filter is turned off as the attenuation value required for a single antenna of the transmit array to transmit alone while the rest of the transmit channels are turned off;

[0112] Traverse different attenuation values S of the transceiver simultaneous array antenna;

[0113] For each attenuation value S, let one transmit channel transmit, apply this attenuation value S to the remaining turned-off transmit channels, and use Monte Carlo simulation to analyze the impact of the self-interference coupled to the analog-to-digital converter at the receiving antenna when there are random phase shifts in the remaining turned-off transmit channels;

[0114] Select the attenuation value S with less impact;

[0115] Verify whether there is a hardware configuration in the transmit link of the transceiver simultaneous array that can achieve the above attenuation value, such as the power amplifier leakage adjustment or digital control attenuator that can be individually controlled in an analog phased array, the digital transmit baseband control board in a digital phased array, etc.;

[0116] If there is, obtain the received signal power range corresponding to the attenuation value S with less impact.

[0117] Or,

[0118] Define the attenuation value S when the transceiver simultaneous array antenna switch filter is turned off as the attenuation value required for a single antenna of the receive array to receive alone while the rest of the receive channels are turned off;

[0119] Traverse different attenuation values S of the transceiver simultaneous array antenna;

[0120] For each attenuation value S, let one transmit channel transmit, one receive channel receive, apply this attenuation value S to the remaining turned-off receive channels, and use Monte Carlo simulation to analyze the impact of the self-interference coupled to the analog-to-digital converter at the receiving antenna when there are random phase shifts in the remaining turned-off receive channels;

[0121] Select the attenuation value S with less impact;

[0122] Verify whether there is a hardware configuration in the receive link of the transceiver simultaneous array that can achieve the above attenuation value, such as the low-noise amplifier leakage adjustment or digital control attenuator that can be individually controlled in an analog phased array, the digital receive baseband control board in a digital phased array, etc.;

[0123] If there is, obtain the received signal power range corresponding to the attenuation value S with less impact.

[0124] In a further embodiment, using Monte Carlo simulation to analyze the impact of the self-interference coupled to the receiving antenna when there are random phase shifts in the remaining turned-off transmit channels includes:

[0125] Evaluate the influence of the remaining closed transmit channels with random phase shifts on the coupled self-interference at the receiving antenna using the relative mean square error, where the relative mean square error is defined as the ratio of the mean square error of channel estimation to the square of the amplitude of the channel estimation result.

[0126] In a further embodiment, obtaining the received signal power range corresponding to the attenuation value S with less influence, including:

[0127]

[0128] In the formula, P kj is the received signal power when the j-th antenna transmits alone and the k-th antenna receives alone, and V ref is the reference voltage of the analog-to-digital converter in the receiving link of the simultaneous transmit-receive array, and P min is the minimum received signal power that ensures a relatively small mean square error in the self-interference coupling channel estimation and is not affected by quantization errors.

[0129] In a further embodiment, dynamically transform the transmit-receive configuration and receive gain of the simultaneous transmit-receive array so that the received signal power is within the received signal power range, including:

[0130] Control the transmit antennas of the simultaneous transmit-receive array to transmit alone in sequence, and the receive antennas of the simultaneous transmit-receive array to receive alone in sequence;

[0131] Control the receive gain of the receive antennas of the simultaneous transmit-receive array so that the received signal power is within the received signal power range;

[0132] Save the transmitted signal, received signal, and receive gain for each configuration.

[0133] In a further embodiment, control the receive gain of the receive antennas of the simultaneous transmit-receive array so that the received signal power is within the received signal power range, including:

[0134] Calculate the received signal power;

[0135] If the received signal power is less than the minimum received signal power, increase the receive gain:

[0136] G kj (m + 1) = G kj (m) + ΔG, P kj ≤P min

[0137] If the received signal power is greater than the maximum received signal power, decrease the receive gain:

[0138]

[0139] In the formula, m is the iteration number of adjusting the receive gain, and Gkj $(m)$ is the received gain at the $m$-th iteration, and $\Delta G$ is the adjustment step size of the received gain, with the unit of dB;

[0140] If the received signal power is within the received signal power range, end the loop, calculate the difference between the received gain at this time and the initial received gain, and construct the transmit power difference matrix $G$ Δ,dB , in this embodiment, $G$ Δ,dB is a matrix with 4 rows and 8 columns.

[0141] In a further embodiment, measure the coupling channels for each transceiver configuration of the simultaneous transceiver array to obtain the coupling matrix:

[0142] For measuring the coupling channels for each transceiver configuration to obtain the coupling matrix, the least squares (LS) channel estimation method or the recursive least squares (RLS) channel estimation method can be selected to estimate the transmit and receive signals of each individual transmitting antenna and individual receiving antenna.

[0143] Specifically, the received signal expressions of each individual transmitting antenna and individual receiving antenna are:

[0144]

[0145] where $k'$ is the receiving antenna number, $j'$ is the transmitting antenna number, $k$ is the current number of the individual receiving antenna, $j$ is the current number of the individual transmitting antenna, and $s$ t,j' is the switched filter value of the $j'$-th transmitting antenna. If $j' = j$, $s$ t,j' $= 1$; if $j' \neq j$, $s$ t,j' $= S$, and $s$ r,k' is the switched filter value of the $k'$-th receiving antenna. If $k' = k$, $s$ r,k' $= 1$; if $k' \neq k$, $s$ r,k' $= S$;

[0146] Specifically, using the least squares channel estimation method, after performing Fourier transform on the saved individual transmit and receive signals and then dividing them, and then dividing by the received gain difference and the transmit-receive link amplitude-phase error, the self-interference channel estimation between antennas is obtained as:

[0147]

[0148] In the formula, represents the self-interference channel between the $j$-th transmitting antenna and the $k$-th receiving antenna obtained by using the least squares channel estimation method, and $Y$ kj (e jω ), $X$ kj (e jωrepresent the Fourier transforms of the received signal and the transmitted signal respectively, Γ tj represents the transmission amplitude and phase error of the j-th transmit antenna, Γ rk represents the reception amplitude and phase error of the k-th receive antenna, G Δ,kj is the received gain adjustment difference when antenna j transmits alone and antenna k receives alone, and the unit is converted from dB to 1;

[0149] Construct the estimated center frequency point coupling matrix between the simultaneous transmit-receive array antennas:

[0150]

[0151] In the formula, is the coupling matrix estimated by using the least squares channel estimation method;

[0152] Adopt the recursive least squares channel estimation method, perform RLS adaptive filtering estimation on the saved signals of single transmit and receive to obtain the converged weights, and then divide by the received gain difference and the amplitude-phase error of the transmit-receive link to obtain the self-interference channel estimation between the antennas as:

[0153]

[0154] In the formula, represents the self-interference channel between the j-th transmit antenna and the k-th receive antenna obtained by using the recursive least squares channel estimation method, N is the filter length, w kj,i is the i-th weight after the recursive least squares algorithm converges, i = 1,..., N - 1, Γ tj represents the transmission amplitude and phase error of the j-th transmit antenna, Γ rk represents the reception amplitude and phase error of the k-th receive antenna, G Δ,kj is the received gain adjustment difference when antenna j transmits alone and antenna k receives alone, and the unit is converted from dB to 1;

[0155] Construct the estimated center frequency point coupling matrix between the simultaneous transmit-receive array antennas:

[0156]

[0157] In the formula, is the coupling matrix estimated by using the recursive least squares channel estimation method.

[0158] In the embodiments of the present invention, by analyzing the minimum attenuation value of the required switched filter for the antenna to transmit alone, it is determined whether the array has the hardware conditions for self-measurement; the influence of the amplitude-phase error of the transmit-receive link on the coupling matrix estimation is considered, and the system coupling matrix and the inter-antenna coupling matrix are distinguished; a method based on least squares channel estimation and recursive least squares channel estimation is used to estimate the self-interference coupling matrix; the influence of the number of bits occupied by the received signal on the receive ADC on the self-interference estimation is analyzed, and the receive power needs to be dynamically adjusted to achieve a better estimation effect. First, HFSS is used to obtain the theoretical value of the inter-antenna coupling matrix, and the amplitude-phase error of the transmit-receive link is measured; then it is confirmed whether the hardware conditions meet the self-measurement conditions of coupling; then the transmit antennas are made to transmit in turn, and the receive antennas receive in turn, and the receive power is adaptively adjusted; a method based on least squares channel estimation or recursive least squares channel estimation is used to estimate the self-interference channel; the influence of the amplitude-phase error and the receive power adjustment is removed to obtain the coupling matrix between the transmit antenna and the receive antenna.

[0159] Embodiment 3

[0160] Based on Embodiment 1 and Embodiment 2, this embodiment further describes the calculation of the effective isotropic isolation achieved by beamforming and digital cancellation according to the measured coupling matrix.

[0161] In the simultaneous transceiver array digital cancellation architecture, the effective isotropic isolation of the transmit beam is:

[0162]

[0163] The effective isotropic isolation of the receive beam is:

[0164]

[0165] Where P t is the transmit power, G t is the transmit antenna gain, G r represents the receive antenna gain. b t is the transmit beamforming vector, b r is the receive beamforming vector, q t is the steering vector of the transmit array, q r is the steering vector of the receive array, b t and q t are complex column vectors of length 8, b r and q r are complex column vectors of length 4. g t and g r are the radiation patterns of the transmit and receive array elements respectively; is the system noise covariance matrix calculated using the transmit beamforming vector and the estimated center frequency coupling matrix between the simultaneous transmit and receive array antennas. is the system noise covariance matrix calculated using the receive beamforming vector and the estimated center frequency coupling matrix between the simultaneous transmit and receive array antennas. φ represents the azimuth angle in the spherical coordinate system; θ represents the elevation angle in the spherical coordinate system.

[0166] Specifically, the expression for the effective radiated power of the transmit array is:

[0167]

[0168] The expression for the receive array gain is:

[0169]

[0170] Optionally, calculating the effective isotropic isolation achieved by beamforming and digital cancellation based on the measured coupling matrix includes:

[0171] Performing transmit beamforming using a transmit beamforming algorithm that minimizes the maximum incident power of all receive array elements;

[0172] Performing receive beamforming using a receive beamforming algorithm that maximizes the signal-to-interference-plus-noise ratio;

[0173] Performing digital cancellation based on the beamforming;

[0174] Calculating the effective isotropic isolation for each step.

[0175] Embodiment 4

[0176] Based on Embodiments 1 to 3, this embodiment demonstrates the effectiveness of the methods in Embodiments 1 to 3.

[0177] As Figure 5 shown, the coupling error is affected by the attenuation value of the switched-off channel switch filter. Figure 5 The left figure of... depicts the maximum amplitude and phase of the error between the coupled self-interference signal at the receive antenna and the ideal value after applying a given attenuation value S and random phase shifts within a certain range to the remaining switched-off transmit channels when the transmit antenna transmits alone. The right figure depicts the maximum amplitude and phase of the error between the coupled self-interference signal at the receive ADC and the ideal value after applying a given attenuation value S and random phase shifts within a certain range to the remaining switched-off receive channels when the transmit antenna transmits alone and the receive antenna receives alone. It can be seen that the larger the attenuation value of the switch filter in the transmit and receive links, the smaller the coupled self-interference error. When the attenuation value is less than -50 dB, the error amplitude caused by random phase shifts within a 45° range is less than 1 dB, and the phase shift is less than 5°.

[0178] Figure 6 The relative mean square error of channel estimation is affected by the number of bits of the received signal occupying the received ADC. It describes the relative mean square error of channel estimation after the received signal amplitude is changed and the signal passes through an ADC with a fixed reference voltage and 8 quantization bits. The experimental results show that when the received signal is small and the number of bits of the received signal occupying the received ADC is less than 4, due to the influence of quantization error, the relative mean square error of channel estimation increases significantly. When the number of bits of the received signal occupying the received ADC is greater than 4, the relative mean square error of channel estimation of both methods is small. The RLS method is hardly affected by the number of bits of the received signal occupying the received ADC, but the relative mean square error is greater than that of the LS method.

[0179] Figure 7 The amplitude and phase of the coupling matrix estimated using the LS and RLS methods. Figure 8 The amplitude and phase of the estimation error between the coupling matrix estimated using the LS and RLS methods and the true value of the coupling matrix. The experiment uses Simulink of Matlab to simulate the transceiver simultaneous array according to the Figure 3 structure in, and uses the Figure 4 coupling self-measurement scheme process in for simulation. The transmitted signal is a narrowband chirp signal with a center frequency of 9 GHz, a bandwidth of 20 MHz, and a pulse width of 1 μs. To measure the accuracy of the coupling matrix estimation, the signals are directly led out at both ends of the transmitting and receiving antennas in the Simulink model to measure the coupling matrix, simulating the traditional method of directly measuring the coupling matrix at the antenna end using a vector network analyzer, and using this coupling matrix as the true value to compare with the method of the present invention. The filter length of the RLS algorithm is 8. The experimental results show that the error of the coupling matrix estimated by the LS method approaches 0, and there is a uniform amplitude offset of 0.32 dB and a phase offset of 0.6° for the elements of the coupling matrix estimated by the RLS method. This offset is small and does not affect the reflection of the relative value of the coupling situation between the transmitting and receiving antennas at the same time. It may be due to the limited filter length of the RLS algorithm. The limited filter length of the RLS algorithm can reduce the computational amount of channel estimation.

[0180] Figure 9For the self-interference signal power and effective isotropic isolation at different scanning angles, uniform beamforming (CBF), uniform beamforming and baseband digital cancellation (CBF+SIC), and transmit-receive array adaptive beamforming (ABF) and baseband digital cancellation (ABF+SIC) using the coupling matrix true value, LS, and RLS methods to estimate the coupling matrix respectively are compared. The experimental results show that after performing transmit-receive array adaptive beamforming and digital cancellation, an isolation of 135 dB can be achieved on average, which is 46 dB higher than the average isolation of 89 dB of uniform beamforming, and the maximum isolation of 153.25 dB can be achieved at some angles. At the same time, the results show that the curves of the self-interference signal power and effective isotropic isolation of transmit-receive array adaptive beamforming (ABF) and digital cancellation (ABF+SIC) using the coupling matrix true value, LS, and RLS methods to estimate the coupling matrix respectively basically coincide, indicating that the coupling matrix estimated by the coupling matrix self-measurement scheme of the present invention is effective, and the same effect can be achieved in self-interference suppression compared with the coupling matrix obtained by using the traditional measurement method.

[0181] Like reference numerals correspond to like components;

[0182] The terms describing the positional relationship in the drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0183] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the embodiments here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A self-measurement method for the coupling matrix of a simultaneous transceiver array, characterized in that Including the following steps: Obtain the theoretical antenna coupling matrix of the simultaneous transmit and receive array through simulation; Measure the amplitude and phase errors of the transmit and receive arrays of the simultaneous transmit and receive array and store them; Based on the transmit signal and receive signal of the simultaneous transmit and receive array and the theoretical antenna coupling matrix, determine the attenuation value required to turn off the remaining transmit channels when transmitting a single transmit signal, and determine the receive signal power range; Dynamically transform the transmit and receive configuration and receive gain of the simultaneous transmit and receive array so that the receive signal power is within the receive signal power range; Measure the coupling channels under each transmit and receive configuration of the simultaneous transmit and receive array to obtain the coupling matrix.

2. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 1, wherein The obtaining of the theoretical antenna coupling matrix of the simultaneous transmit and receive array through simulation includes: The theoretical antenna coupling matrix of the simultaneous transmit and receive array is a J×K complex matrix, where the element in the j-th row and k-th column is defined as the propagation coefficient from the j-th transmit antenna to the k-th receive antenna, and J and K are the total numbers of transmit antennas and receive antennas respectively; Obtain the theoretical antenna coupling matrix of the simultaneous transmit and receive array through HFSS simulation.

3. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 2, wherein The amplitude and phase errors of the transmitting and receiving array include the transmitting amplitude and phase error Γ t and the receiving amplitude and phase error Γ r . Among them, the transmitting amplitude and phase error Γ t is the propagation coefficient from the digital-to-analog converter to the antenna end of the transmitting link when the transmitting link gain and beamforming weight of the simultaneous transmitting and receiving array are equal. The receiving amplitude and phase error Γ r is the propagation coefficient from the analog-to-digital converter to the antenna end of the receiving link when the receiving link gain and beamforming weight of the simultaneous transmitting and receiving array are equal.

4. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 3, characterized in that Measuring the amplitude and phase errors of the transmit and receive arrays of the simultaneous transmit and receive array and storing them includes: Measure the amplitude and phase errors of the transmit and receive arrays of the simultaneous transmit and receive array through a vector network analyzer or near-field measurement and store them.

5. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 4, characterized in that, Based on the transmit signal and receive signal of the simultaneous transmit and receive array and the theoretical antenna coupling matrix, determining the attenuation value required to turn off the remaining transmit channels when transmitting a single transmit signal and determining the receive signal power range includes: Define the attenuation value S at which the antenna switch filter of the simultaneous transmit and receive array is turned off as the attenuation value required for a certain antenna of the transmit array to transmit alone while the remaining transmit channels are turned off; Traverse different attenuation values S of the antennas of the simultaneous transmit and receive array; For each attenuation value S, let one transmit channel transmit, apply this attenuation value S to the remaining turned-off transmit channels, and use Monte Carlo simulation to simulate the influence of the random phase shift of the remaining turned-off transmit channels on the coupling self-interference at the receive antenna's digital-to-analog converter; Select the attenuation value S with less influence; Confirm whether there is a hardware configuration in the transmit link of the simultaneous transmit and receive array that can reach the above attenuation value; If so, obtain the receive signal power range corresponding to the attenuation value S with less influence.

6. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 5, characterized in that Using Monte Carlo simulation to simulate the influence of the random phase shift of the remaining turned-off transmit channels on the coupling self-interference at the receive antenna includes: Use the relative mean square error to evaluate the influence of the random phase shift of the remaining turned-off transmit channels on the coupling self-interference at the receive antenna, where the relative mean square error is defined as the ratio of the mean square error of channel estimation to the square of the amplitude of the channel estimation result.

7. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 6, characterized in that Obtaining the receive signal power range corresponding to the attenuation value S with less influence includes: Where P kj is the received signal power when the j-th antenna transmits alone and the k-th antenna receives alone, and V ref is the reference voltage of the analog-to-digital converter in the receive link of the simultaneous transmit and receive array, and P min is the minimum received signal power that ensures a relatively small mean square error in the self-interference coupling channel estimation and is not affected by quantization errors.

8. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 7, characterized in that Dynamically transforming the transmit and receive configuration and receive gain of the simultaneous transmit and receive array so that the receive signal power is within the receive signal power range includes: Control the transmit antennas of the simultaneous transmit and receive array to transmit alone in sequence, and the receive antennas of the simultaneous transmit and receive array to receive alone in sequence; Control the receive gain of the receive antennas of the simultaneous transmit and receive array so that the receive signal power is within the receive signal power range; Save the transmit signal, receive signal, and receive gain for each configuration.

9. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 8, characterized in that, Controlling the reception gain of the receiving antennas of the simultaneous transceiver array such that the received signal power is within the received signal power range, including: Calculating the received signal power; If the received signal power is less than the minimum received signal power, increasing the reception gain: G kj (m + 1) = G kj (m) + ΔG,P kj ≤P min If the received signal power is greater than the maximum received signal power, decreasing the reception gain: where m is the number of iterations for adjusting the reception gain, and G kj (m) is the reception gain at the m-th iteration, and ΔG is the adjustment step size of the reception gain, with the unit of dB; If the received signal power is within the received signal power range, end the loop, calculate the difference between the received gain at this time and the initial received gain, and construct the transmit power difference matrix G Δ,dB .

10. The self-measurement method of the coupling matrix of the simultaneous transceiver array according to claim 9, characterized in that, Measuring the coupling channels under each transceiver configuration of the simultaneous transceiver array to obtain a coupling matrix: Using the least squares channel estimation method to obtain the self-interference channel estimation between antennas as: In the formula, represents the self-interference channel between the j-th transmit antenna and the k-th receive antenna obtained by using the least squares channel estimation method, Y kj (e jω ), X kj (e jω ) respectively represent the Fourier transforms of the received signal and the transmitted signal, Γ tj represents the transmission amplitude and phase error of the j-th transmit antenna, Γ rk represents the reception amplitude and phase error of the k-th receive antenna, G Δ,kj is the received gain adjustment difference when antenna j transmits alone and antenna k receives alone, and the unit is converted from dB to 1; Constructing an estimated coupling matrix: In the formula, is the coupling matrix estimated by the least square channel estimation method; Using the recursive least squares channel estimation method to obtain the self-interference channel estimation between antennas as: In the formula, represents the self-interference channel between the j-th transmit antenna and the k-th receive antenna obtained by the recursive least squares channel estimation method. N is the filter length, and w kj,i is the i-th weight after the convergence of the recursive least squares algorithm, where i = 1,..., N - 1, and Γ tj represents the transmit amplitude and phase error of the j-th transmit antenna, and Γ rk represents the receive amplitude and phase error of the k-th receive antenna. G Δ,kj is the difference in receive gain adjustment when antenna j transmits alone and antenna k receives alone. The unit is converted from dB to 1; Constructing an estimated coupling matrix: wherein, is the coupling matrix estimated by using the recursive least squares channel estimation method.

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