Distributed same-frequency interference suppression method and architecture oriented to regional symbiosis

Abstract

The invention discloses a regional symbiosis-oriented distributed same-frequency interference suppression method and architecture. The method comprises the following steps: a desired signal node generates a desired signal and transmits the desired signal through an antenna; the distributed interference node generates an interference signal and transmits the interference signal through an antenna; authorizing the receiving node to receive and process the signal to obtain a receiving signal after down-conversion; the method comprises the following steps: converting a received distributed interference signal into a real part and imaginary part form, expanding a time error and a residual frequency offset to obtain an interference signal expression after expansion of the time error and the residual frequency offset, and combining non-time-varying coefficients before real part quantity and imaginary part quantity of the interference signal into one item to obtain an interference signal expression after expansion of the time error and the residual frequency offset; and obtaining a reconstruction coefficient expression of distributed interference, estimating a distributed interference suppression architecture model coefficient, and reconstructing an interference signal to carry out distributed interference suppression so as to obtain a desired signal. According to the method, the distributed interference signal reconstruction and suppression under the constraints of time error, frequency deviation and IQ imbalance are realized.

Description

Technical Field

[0001] The present invention relates to a method for suppressing co-channel interference, and in particular to a distributed method and architecture for suppressing co-channel interference for regional symbiosis. Background Art

[0002] In electromagnetic attack and defense scenarios, our equipment emits interference signals to suppress the enemy's electromagnetic equipment, thereby curbing the enemy's right to use the electromagnetic spectrum. Distributed interference can be implemented on small platforms such as drones. Its high flexibility and high anti-destruction capabilities are more in line with the needs of modern electronic battlefields than common platform interference.

[0003] The key to achieving regional symbiosis between our equipment and distributed interference is to correctly implement distributed co-frequency interference suppression. Our authorized receiver uses pre-stored prior information to reconstruct the distributed interference signal to suppress interference, eliminate interference effects and achieve regional symbiosis. However, distributed interference devices have motion characteristics, which may introduce the Doppler effect and cause dynamic changes in propagation delay, making it difficult to accurately synchronize time and frequency. In addition, the use of direct conversion transceivers in up and down conversion will introduce IQ imbalance problems. The above non-ideal factors may lead to deterioration of interference suppression performance. Existing common platform interference suppression methods are difficult to overcome the problems existing in distributed interference scenarios, so it is necessary to study interference suppression technologies for distributed multi-node scenarios. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a distributed co-frequency interference suppression method and architecture for regional symbiosis, which realizes the reconstruction and suppression of distributed interference signals under the constraints of time error, frequency offset and IQ imbalance, and effectively solves the problem of deterioration of interference suppression performance in distributed interference scenarios.

[0005] The object of the present invention is to achieve the following technical solution: a distributed co-channel interference suppression method for regional symbiosis, comprising the following steps:

[0006] S1. The desired signal node generates the desired signal and transmits it through the antenna;

[0007] S2. The distributed interference node generates an interference signal and transmits it through the antenna;

[0008] S3. Authorize the receiving node to receive and process the signal to obtain the received signal after down-conversion;

[0009] S4. Convert the received distributed interference signal into the form of real and imaginary parts;

[0010] S5. Expand the time error using a 2P+1 order interpolation filter, thereby converting the time error into a time-invariant coefficient, and obtaining an interference signal expression after the delay error is expanded;

[0011] S6. Expand the residual frequency deviation using an M-order Taylor series, convert the residual frequency from an exponential form to a polynomial form, and obtain an interference signal expression after the time error and the residual frequency deviation are expanded;

[0012] S7. Combining the time-invariant coefficients before the real and imaginary components of the interference signal into one term, thereby obtaining a reconstruction coefficient expression for the distributed interference;

[0013] S8. Estimate the coefficients of the distributed interference suppression architecture model at the authorized receiving node, reconstruct the interference signal to perform distributed interference suppression, and obtain the desired signal.

[0014] A distributed co-channel interference suppression architecture for regional symbiosis, including:

[0015] A desired signal node, used for generating a desired signal and transmitting it through an antenna;

[0016] A distributed jamming node, used to generate jamming signals and transmit them through antennas;

[0017] The authorized receiving node is used to receive and process the signal to obtain the received signal after down-conversion; the received distributed interference signal is converted into the form of real and imaginary parts, the time error and residual frequency offset are expanded to obtain the interference signal expression after the time error and residual frequency offset are expanded, the non-time-varying coefficients before the real and imaginary components of the interference signal are combined into one term to obtain the reconstruction coefficient expression of the distributed interference, and the coefficients of the distributed interference suppression architecture model are estimated, and the interference signal is reconstructed to perform distributed interference suppression to obtain the desired signal.

[0018] The beneficial effects of the present invention are as follows: the present invention realizes the reconstruction and suppression of distributed interference signals under the constraints of time error, frequency offset and IQ imbalance, and effectively solves the problem of deterioration of interference suppression performance in distributed interference scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a flow chart of the method of the present invention;

[0020] Figure 2 A schematic diagram of a distributed interference suppression architecture for overcoming regional symbiosis in an embodiment;

[0021] Figure 3 Schematic diagram of the relationship between the distributed interference suppression performance and the error size in the embodiment;

[0022] Figure 4 Schematic diagram of the relationship between the distributed interference suppression performance and the model expansion order in the embodiment; DETAILED DESCRIPTION

[0023] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0024] like Figure 1 As shown, a distributed co-channel interference suppression method for regional symbiosis includes the following steps:

[0025] S1: The desired signal node generates the desired signal and transmits it through the antenna. The baseband desired signal is s(n), which is converted to s(t) after DAC. Since the desired signal node is deployed separately from the interference node, for the convenience of analysis, the IQ imbalance of the desired signal node is not considered, and the desired signal after up-conversion is x s (t), its expression is:

[0026]

[0027] Among them, s i (t) and s q (t) are the real and imaginary parts of s(t), respectively, and f s is the carrier frequency.

[0028] S2: Distributed interference nodes generate interference signals and transmit them through antennas. A total of L interference nodes are set up to transmit the same interference signal. The baseband interference is denoted as c(n), which is converted to c(t) after DAC. Considering the IQ imbalance at the distributed interference node, that is, the amplitude and phase between the I-channel and Q-channel carriers used for up-conversion are not completely suppressed. Taking the I-channel as the reference, it is assumed that the phase and amplitude errors exist in the Q-channel. The up-conversion carrier signal generated by the local oscillator can be recorded as:

[0029] u l (t) = cos(2πf l t)+jα Tl sin(2πf l t+θ Tl ) (2)

[0030] Among them, f l is the carrier frequency corresponding to the lth interfering node, α Tj With θ Tj They represent the amplitude imbalance and phase imbalance at the oscillator of the lth distributed interference node respectively. When there is no IQ imbalance, there is α Tl =1,θ Tl =0°.

[0031] The interference signal x after up-conversion l (t)(l=1,2,...,L) can be expressed as:

[0032]

[0033] S3. The authorized receiving node receives the signal, converts the received analog signal into a digital signal through ADC, and synchronizes the time with the reference interference sequence c(n) stored at the authorized receiving node. The obtained signal is expressed as:

[0034]

[0035] Among them, ε s With ε l is the channel fading coefficient corresponding to the desired signal and the lth interference signal, τ s With τ l They represent the normalized time delay of the desired signal and the distributed interference signal after time synchronization, and w′(n) is the AWGN signal, which is independent of the desired signal and the interference signal.

[0036] Considering that there is also IQ imbalance at the authorized receiving node, the received signal is down-converted and the oscillation frequency of the down-conversion is recorded as f d , the generated down-converted carrier signal is:

[0037] v(t)=cos(2πf d t)-jα R sin(2πf d t+θ R ) (5)

[0038] The received signal after down-conversion is:

[0039] r(n)=r c (n)+r s (n)+w(n) (6)

[0040] r c (n) is the interference signal obtained by down-conversion processing, and its expression is:

[0041]

[0042] Where, ΔF l =(f r -f l )T is the normalized residual frequency deviation, T is the sampling period, ξ 1l With ξ 2l is the composite channel coefficient corresponding to the original component and the image component of the interference signal, and the expression is:

[0043]

[0044] in, α R With θ R They represent the amplitude imbalance and phase imbalance of the oscillator at the authorized receiving node respectively.

[0045] S4. Convert the received distributed interference signal into the form of real part and imaginary part. Observing the expression of the interference signal after down-conversion, it can be seen that the received distributed interference signal r c (t) is composed of the interference sequence c(n) and its conjugate term c * (n), since c(n) and c * (n) There is a correlation. Assuming that the imaginary and real parts of the interference signal are independent and identically distributed, the interference signal in the received signal expression is converted into the expression of the real and imaginary parts, that is:

[0046]

[0047] Among them, c i (n) represents the real part of the interference sequence, c q (n) represents the imaginary part of the interference sequence.

[0048] S5. The normalized time delay error τ that still exists after the distributed interference signal and the reference interference sequence c(n) are synchronized using a 2P+1 order interpolation filter l Expand it to convert the time error into a time-invariant coefficient, namely:

[0049]

[0050] Among them, the interpolation filter coefficients are:

[0051]

[0052] Therefore, the interference signal expression after the delay error is:

[0053]

[0054] S6. Normalize the residual frequency deviation ΔF l Using the M-order Taylor series to expand, the residual frequency is converted from exponential form to polynomial form, that is:

[0055]

[0056]

[0057] Therefore, after the time error and residual frequency offset are expanded, the interference signal expression is:

[0058]

[0059] S7. Combine the time-invariant coefficients before the real and imaginary components of the interference signal into one term, thereby obtaining the reconstruction coefficient expression of the distributed interference, namely:

[0060] In step S7, the reconstructed expression of the distributed interference is:

[0061]

[0062] Among them, the expression of time-invariant coefficient is:

[0063]

[0064] S8. Estimate the coefficients of the distributed interference suppression architecture model at the authorized receiving node. Set two sets of multi-tap filters at the authorized receiving node, and the inputs are the real and imaginary components of the processed distributed interference signal. The output signals of the multi-tap filters are added to obtain the reconstructed distributed interference signal. The tap coefficients are calculated below.

[0065] The tap coefficient can be expressed as a [2(M+1)×(2P+1)]×1-dimensional vector, that is:

[0066] z(n)=[a0,...,a m ,...,a M ,b0,...,b m ,...,b M ] T (20)

[0067] a m =[a m,-P ,...,a m,0 ,...,a m,P ] T (twenty one)

[0068] b m =[b m,-P ,...,b m,0 ,...,b m,P ] (twenty two)

[0069] The input reference interference signal vector is multiplied by the coefficient vector to obtain the reconstructed signal. The expression of the reconstructed signal is:

[0070]

[0071] Among them, the input reference interference signal vector is:

[0072] Y(n)=[y i0 (n),...,y im (n),...,y iM (n),y q0 (n),...,y qm (n),...,y qM (n)] T (twenty four)

[0073] Among them, the vector corresponding to the real component is:

[0074] y im (n)=[n m c i (n+P),...,n m c i (n),...,n m c i (nP)] (25)

[0075] The vector corresponding to the imaginary component is:

[0076] y qm (n) = [jn m c q (n+P),...,jn m c q (n),...,jn m c q (nP)] (26)

[0077] According to the minimization of mean square error (MMSE) criterion, the minimization objective function is:

[0078] J(z)=E[|e(n)|]=E[|r(n)-z T (n)Y(n)|] (27)

[0079] The least mean square (LMS) algorithm is used to solve the coefficients. The algorithm flow is shown below.

[0080]

[0081] The authorized receiving node reconstructs the interference signal to perform distributed interference suppression and obtain the desired signal: the real part c of the reference interference sequence c(n) pre-stored by the authorized receiving node is i (n) and the imaginary part c q (n) Input multi-tap filter for interference reconstruction:

[0082]

[0083] Subtract the reconstructed interference signal from the received signal r(n) to recover the desired signal, that is:

[0084]

[0085] like Figure 2 As shown, a distributed co-channel interference suppression architecture for regional symbiosis includes:

[0086] A desired signal node, used for generating a desired signal and transmitting it through an antenna;

[0087] A distributed jamming node, used to generate jamming signals and transmit them through antennas;

[0088] The authorized receiving node is used to receive and process the signal to obtain the received signal after down-conversion; the received distributed interference signal is converted into the form of real and imaginary parts, the time error and residual frequency offset are expanded to obtain the interference signal expression after the time error and residual frequency offset are expanded, the non-time-varying coefficients before the real and imaginary components of the interference signal are combined into one term to obtain the reconstruction coefficient expression of the distributed interference, and the coefficients of the distributed interference suppression architecture model are estimated, and the interference signal is reconstructed to perform distributed interference suppression to obtain the desired signal.

[0089] The following is a simulation analysis and evaluation of the proposed distributed co-channel interference suppression architecture and method for regional symbiosis. The specific parameter settings are shown in the following table.

[0090] Table 1 Simulation parameter settings of distributed co-channel interference suppression architecture and method for regional symbiosis

[0091]

[0092] Figure 3 The figure shows the variation of the interference suppression ratio JCR with the interference to noise ratio JNR when the time-frequency error and IQ imbalance are different. A total of three distributed interference nodes are set. It is assumed that the three interference nodes have the same IQ imbalance as the authorized receiving node, and the corresponding time-frequency errors at the authorized receiving node are the same. The delay frequency error expansion order is P=M=3. The figure plots the distributed interference suppression method proposed in this patent and the traditional common platform interference suppression method when the error value is τ=0.04, ΔF=10 -6 , α=1.005, θ=0.5°, τ=0.1, ΔF=10 -5 , α=1.01, θ=1°, τ=0.2, ΔF=10 -4 , simulation results when α=1.03, θ=3°. It can be seen from the curve that when the time-frequency error and IQ imbalance are very small, the patented method can make the JCR close to the received JNR, and the distributed interference suppression performance is close to its theoretical limit. When JNR=25dB, as the error value increases, the patented method can improve the JCR by 4.31dB, 10.44dB and 15.89dB respectively compared with the common platform method. And as the JNR increases, the interference suppression performance is improved more significantly, indicating that the patented method can effectively reduce the impact of time-frequency error and IQ imbalance in distributed interference scenarios.

[0093] Figure 4The figure shows how the interference suppression ratio JCR changes with the interference-to-noise ratio JNR when the time-frequency error expansion order is different. Set τ = 0.2, ΔF = 10 -4 , α=1.02, θ=3°. The curves in the figure represent the simulation results when the expansion order P=M=1, 2, 3, as well as the theoretical results and simulation results of the common platform method. It can be seen from the curve that when the common platform method is adopted, the JCR is stable at 8.56dB. At this time, the interference suppression performance is poor, which will cause the authorized receiving node to fail to successfully and correctly recover the expected signal. When the method of this patent is adopted, as the expansion order increases, the JCR increases significantly, and the distributed interference suppression performance is significantly improved compared with the common platform method, indicating that the method of this patent can improve the distributed interference suppression performance by increasing the expansion order.

[0094] The above is a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A distributed co-channel interference suppression method for regional symbiosis, characterized by: The following steps are involved: S1. The desired signal node generates the desired signal and transmits it through the antenna; S2. The distributed interference node generates an interference signal and transmits it through the antenna; S3. Authorize the receiving node to receive and process the signal to obtain the received signal after down-conversion; S4. Convert the received distributed interference signal into the form of real and imaginary parts; S5. Expand the time error using a 2P+1 order interpolation filter, thereby converting the time error into a time-invariant coefficient, and obtaining an interference signal expression after the delay error is expanded; S6. Expand the residual frequency deviation using an M-order Taylor series, convert the residual frequency from an exponential form to a polynomial form, and obtain an interference signal expression after the time error and the residual frequency deviation are expanded; S7. Combining the time-invariant coefficients before the real and imaginary components of the interference signal into one term, thereby obtaining a reconstruction coefficient expression for the distributed interference; S8. Estimate the coefficients of the distributed interference suppression architecture model at the authorized receiving node, reconstruct the interference signal to perform distributed interference suppression, and obtain the desired signal.

2. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: The step S1 comprises: S101. The baseband desired signal is s(n), which is converted to s(t) after DAC. Since the desired signal node and the interference node are deployed separately, the IQ imbalance of the desired signal node is not considered. The desired signal after up-conversion is x s (t), its expression is: Among them, s i (t) and s q (t) are the real and imaginary parts of s(t), respectively, and f s is the carrier frequency; S102. The expected signal node converts the up-converted expected signal x s (t) Transmitted through an antenna.

3. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: The step S2 comprises: S201. Assume that a total of L interference nodes are set up, transmitting the same interference signal: The baseband interference is denoted as c(n), which is converted to c(t) after DAC. Considering the IQ imbalance at the distributed interference node, that is, the amplitude and phase between the I-channel and Q-channel carriers used for up-conversion are not completely suppressed. Taking the I-channel as the reference, it is assumed that the phase and amplitude errors exist in the Q-channel. The up-converted carrier signal generated by the local oscillator of the l-th interference node is recorded as: you l (t)=cos(2πf l t)+ja Tl sin(2πf l t+θ Tl ) (2) Among them, f l is the carrier frequency corresponding to the lth interfering node, α Tl With θ Tl They represent the amplitude imbalance and phase imbalance at the oscillator of the lth distributed interference node respectively. When there is no IQ imbalance, there is α Tl =1,θ Tl =0°; The interference signal after up-conversion at the lth interference node is denoted as x l (t),l=1,2,...,L: S202. Each interference node transmits the up-converted interference signal through an antenna.

4. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: The step S3 comprises: S301. The authorized receiving node receives the signal, converts the received analog signal into a digital signal through ADC, and synchronizes the time with the reference interference sequence c(n) stored at the authorized receiving node. The obtained signal is expressed as: Among them, ε s With ε l is the channel fading coefficient corresponding to the desired signal and the lth interference signal, τ l represents the normalized time delay error that still exists after the received distributed interference signal is time-synchronized with the reference interference sequence c(n), w′(n) is the AWGN signal, which is independent of the desired signal and the interference signal; S302. Considering that there is also an IQ imbalance at the authorized receiving node, the received signal is down-converted and the oscillation frequency of the frequency conversion is recorded as f d , the generated down-converted carrier signal is: v(t)=cos(2πf d t)-ja R sin(2πf d t+θ R ) (5) The received signal after down-conversion is: r(n)=r c (n)+r s (n)+w(n) (6) r c (n) is the interference signal obtained by down-conversion processing, and its expression is: Where, ΔF l =(f r -f l )T is the normalized residual frequency deviation, T is the sampling period, ξ 1l With ξ 2l is the composite channel coefficient corresponding to the original component and the image component of the interference signal, and the expression is: in, α R With θ R They represent the amplitude imbalance and phase imbalance of the oscillator at the authorized receiving node respectively.

5. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: The step S4 comprises: Receive distributed interference signal r c (t) is composed of the interference sequence c(n) and its conjugate term c * (n), since c(n) and c * (n) There is a correlation. Assuming that the imaginary and real parts of the interference signal are independent and identically distributed, the interference signal in the received signal expression is converted into the expression of the real and imaginary parts, that is: Among them, c i (n) represents the real part of the interference sequence, c q (n) represents the imaginary part of the interference sequence.

6. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: The step S5 comprises: The normalized time delay error τ that still exists after the distributed interference signal and the reference interference sequence c(n) are synchronized using a 2P+1 order interpolation filter l Expand it to convert the time error into a time-invariant coefficient, namely: Among them, the interpolation filter coefficients are: Therefore, the interference signal expression after the delay error is:

7. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: The step S6 comprises: The normalized residual frequency offset ΔF l Using the M-order Taylor series to expand, the residual frequency is converted from exponential form to polynomial form, that is: Therefore, after the time error and residual frequency offset are expanded, the interference signal expression is:

8. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: In step S7, the reconstructed expression of the distributed interference is: Among them, the expression of time-invariant coefficient is:

9. The method for suppressing distributed co-channel interference for regional symbiosis according to claim 1, characterized in that: The step S8 comprises: S801. Two sets of multi-tap filters are set at the authorized receiving node, and the inputs are the real and imaginary components of the processed distributed interference signal. The output signals of the multi-tap filters are added to obtain the reconstructed distributed interference signal. The tap coefficients are calculated as follows: The tap coefficient is expressed as a [2(M+1)×(2P+1)]×1-dimensional vector, that is: z(n)=[a0,...,a m ,...,a M ,b0,...,b m ,...,b M ] T (20) a m =[a m,-P ,...,a m,0 ,...,a m,P ] (21) b m =[b m,-P ,...,b m,0 ,...,b m,P ] (22) The input reference interference signal vector is multiplied by the coefficient vector to obtain the reconstructed signal. The expression of the reconstructed signal is: Among them, the input reference interference signal vector is: Y(n)=[y i0 (n),...,and im (n),...,and iM (n),y q0 (n),...,and qm (n),...,and qM (n)] T (24) Among them, the vector corresponding to the real component is: y im (n)=[n m c i (n+P),...,n m c i (n),...,n m c i (n-P)] (25) The vector corresponding to the imaginary component is: y qm (n)=[jn m c q (n+P),...,jn m c q (n),...,jn m c q (n-P)] (26) According to the minimization of mean square error criterion, the minimized objective function is: J(z)=E[|e(n)|]=E[|r(n)-z T (n)Y(n)|] (27) The coefficients are solved using the least mean square algorithm to obtain the estimated value of the coefficient vector z(n); S802. The authorized receiving node reconstructs the interference signal to perform distributed interference suppression and obtains the desired signal: the real part c of the reference interference sequence c(n) pre-stored by the authorized receiving node i (n) and the imaginary part c q (n) Input multi-tap filter for interference reconstruction: Subtract the reconstructed interference signal from the received signal r(n) to recover the desired signal, that is:

10. A distributed co-channel interference suppression architecture for regional symbiosis, using the method described in any one of claims 1 to 9, characterized in that: include: A desired signal node, used for generating a desired signal and transmitting it through an antenna; A distributed jamming node, used to generate jamming signals and transmit them through antennas; The authorized receiving node is used to receive and process the signal to obtain the received signal after down-conversion; The received distributed interference signal is converted into the form of real and imaginary parts, and the time error and residual frequency offset are expanded to obtain the interference signal expression after the time error and residual frequency offset are expanded. The non-time-varying coefficients before the real and imaginary components of the interference signal are combined into one term to obtain the reconstruction coefficient expression of the distributed interference, and the coefficients of the distributed interference suppression architecture model are estimated, and the interference signal is reconstructed for distributed interference suppression to obtain the desired signal.

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