A method and architecture for suppressing electromagnetic spectrum umbrella self-interference to overcome IQ imbalance

Abstract

The present invention discloses a method and architecture for suppressing electromagnetic spectrum canopy self-interference to overcome IQ imbalance. The method comprises the following steps: S1. A communication transmitter within the electromagnetic spectrum canopy generates and transmits a communication signal; S2. A canopy jammer generates and transmits a self-interference signal; S3. A canopy interference suppression receiver preprocesses the received signal to obtain a digital baseband signal; S4. The canopy interference suppression receiver converts the IQ imbalance and delay error into model coefficients of a multi-tap filter; S5. The canopy interference suppression receiver estimates the model coefficients of the multi-tap filter; S6. The canopy interference suppression receiver reconstructs the self-interference signal, performs canopy self-interference suppression, and obtains a communication received signal. The present invention reconstructs and suppresses canopy self-interference signals in the presence of IQ imbalance, effectively solving the problem of deteriorating self-interference suppression performance in the presence of IQ imbalance.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic spectrum umbrellas, and in particular to an electromagnetic spectrum umbrella self-interference suppression method and architecture for overcoming IQ imbalance. Background Art

[0002] By sending self-interference signals to a designated area through an umbrella jammer, an electromagnetic spectrum umbrella can be formed, blocking the communications of unauthorized users within the electromagnetic spectrum umbrella. At the authorized user's site, prior information of the interference signal is used to suppress self-interference, thereby correctly obtaining the communication signal and taking the initiative in the regional electromagnetic spectrum.

[0003] The key to implementing an electromagnetic spectrum umbrella is self-interference suppression. The receiver uses pre-stored prior information to reconstruct the self-interference signal to suppress it, minimizing its impact on authorized users. However, in actual communication transceivers, direct conversion transceivers (DCTs) are often used due to their low cost, small size, and low power consumption. However, this DCT introduces IQ imbalance, resulting in incomplete orthogonality between the in-phase and quadrature components. Existing research on electromagnetic spectrum umbrella self-interference suppression has not proposed solutions to address IQ imbalance and has ignored the impact of transceiver structure on interference suppression performance. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an electromagnetic spectrum umbrella cover self-interference suppression method and architecture to overcome IQ imbalance, reconstruct and suppress the umbrella cover self-interference signal with IQ imbalance, and effectively solve the problem of deterioration of self-interference suppression performance under the condition of IQ imbalance.

[0005] The object of the present invention is achieved through the following technical solution: a method for suppressing electromagnetic spectrum umbrella self-interference to overcome IQ imbalance, comprising the following steps:

[0006] S1. A communication transmitter within the electromagnetic spectrum umbrella generates and transmits a communication signal;

[0007] S2. The canopy jammer generates and transmits a self-jamming signal;

[0008] S3. The umbrella interference suppression receiver preprocesses the received signal to obtain a digital baseband signal;

[0009] S4. The umbrella interference suppression receiver converts the IQ imbalance and delay error into the model coefficients of the multi-tap filter;

[0010] S5. The umbrella interference suppression receiver estimates the model coefficients of the multi-tap filter;

[0011] S6. The umbrella cover interference suppression receiver reconstructs the self-interference signal to suppress the umbrella cover self-interference and obtain the communication receiving signal.

[0012] The beneficial effect of the present invention is that the present invention reconstructs and suppresses the self-interference signal of the umbrella cover with IQ imbalance, and effectively solves the problem of deterioration of the self-interference suppression performance under the condition of IQ imbalance. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a flow chart of the method of the present invention;

[0014] Figure 2 Schematic diagram of an electromagnetic spectrum umbrella self-interference suppression architecture for overcoming IQ imbalance in an embodiment;

[0015] Figure 3 Schematic diagram of the relationship between the umbrella cover self-interference suppression performance and amplitude imbalance in the embodiment;

[0016] Figure 4 Schematic diagram of the relationship between the umbrella cover self-interference suppression performance and phase imbalance in the embodiment. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0018] like Figure 1 As shown, a method for suppressing electromagnetic spectrum umbrella self-interference to overcome IQ imbalance includes the following steps:

[0019] S1. A communication transmitter within the electromagnetic spectrum umbrella generates and transmits a communication signal;

[0020] At the communication transmitter inside the umbrella cover, the communication signal is transmitted after being up-converted by the DAC:

[0021]

[0022] Among them, f s is the carrier frequency.

[0023] S2. The canopy jammer generates and transmits a self-jamming signal;

[0024] At the canopy jammer, the jamming signal is passed through the DAC, up-converted, and then transmitted:

[0025]

[0026] Among them, f u is the carrier frequency, β T and θ T They represent the amplitude imbalance and phase imbalance at the oscillator of the umbrella jammer respectively.

[0027] S3. The umbrella interference suppression receiver preprocesses the received signal to obtain a digital baseband signal;

[0028] At the umbrella cover self-interference suppression receiver, the signal processed by ADC can be expressed as:

[0029]

[0030] Among them, the communication signal and the self-interference signal pass through L s With L u flat fading AWGN channel, g s With g u The corresponding channel fading coefficients, τ s With τ u They represent the time delay experienced by the communication signal and the self-interference signal during channel transmission.

[0031] After down-conversion processing, the self-interference signal is obtained as follows:

[0032]

[0033] in, and is the composite channel coefficient corresponding to the original self-interference component and the image component, and the expression is:

[0034]

[0035] Among them, β R and θ R They represent the amplitude imbalance and phase imbalance of the receiver oscillator suppressed by the umbrella cover self-interference.

[0036] S4. The umbrella interference suppression receiver converts the IQ imbalance and delay error into the model coefficients of the multi-tap filter;

[0037] The delay of the received self-interference signal is expanded using the ideal fractional delay filter, and u(n) and u * (n)Convert to u i (n) and u q (n), we get:

[0038]

[0039] The coefficient expression is:

[0040]

[0041] S5. The umbrella interference suppression receiver estimates the model coefficients (self-interference model coefficients) of the multi-tap filter;

[0042] Two multi-tap filters are set up at the umbrella cover self-interference suppression receiver. The input is the real and imaginary components of the signal after analog-to-digital conversion and down-conversion. The output signals of the two multi-tap filters are combined to obtain the self-interference reconstruction signal. The tap coefficient can be expressed as a [2×(2P+1)]×1-dimensional vector, that is:

[0043] z=[a -P ,...,a0,...,a P ,b -P ,...,b0,...,b P ] T

[0044] Element a in the coefficient vector i is the i+P+1 tap coefficient in the first multi-tap filter, element b i is the i+P+1th tap coefficient in the second multi-tap filter.

[0045] will u i (n) and u q (n) Input the multi-tap filter to obtain the reconstructed signal:

[0046]

[0047] in

[0048] Ω n =[Ω(1),Ω(2),...,Ω(n)] T

[0049] Ω(n)=[u i (n+P),...,u i (n),...,u i (nP),u q (n+P),...,u q (n),...,u q (nP)] T

[0050] The calculation formula for the estimated value of the coefficient vector z is obtained using the least squares (LS) criterion:

[0051]

[0052] in, Represents the coefficient vector estimated by the data of the previous n moments.

[0053] The coefficients are estimated using the recursive least squares (RLS) algorithm. After a certain number of iterative operations, the final estimation result is recorded as the coefficient vector estimate.

[0054] S6. The umbrella cover interference suppression receiver reconstructs the self-interference signal to suppress the umbrella cover self-interference and obtain the communication receiving signal.

[0055] Get the coefficient vector through the RLS algorithm Then we get the coefficients of the multi-tap filter, and use u i (n) and u q (n) The self-interference reconstruction signal is input into the multi-tap filter, and the reconstructed self-interference signal is subtracted from the original received signal to obtain the residual received signal after interference suppression. The residual signal is then subjected to subsequent signal processing such as matched filtering and demodulation.

[0056] like Figure 2 As shown, an electromagnetic spectrum umbrella self-interference suppression architecture for overcoming IQ imbalance includes:

[0057] A communication transmitter, used to generate and transmit communication signals;

[0058] A canopy jammer, used to generate and transmit self-jamming signals;

[0059] The umbrella interference suppression receiver is used to preprocess the received signal to obtain a digital baseband signal, then convert the IQ imbalance and delay error into the model coefficients of the multi-tap filter, estimate the self-interference model coefficients, and reconstruct the self-interference signal to perform umbrella self-interference suppression and obtain the communication reception signal.

[0060] In the embodiments of this application, simulation analysis and evaluation are performed on the proposed electromagnetic spectrum umbrella self-interference suppression architecture and method for overcoming IQ imbalance. Specific parameter settings are shown in the following table.

[0061] Table 1 Simulation parameter settings of the electromagnetic spectrum umbrella self-interference suppression architecture and method to overcome IQ imbalance

[0062]

[0063] Attachment Figure 3 The figure shows the effect of amplitude imbalance on the self-interference suppression performance of the umbrella cover when the JNR value is different. The self-interference suppression ratio JCR is used as the measurement indicator. T =β R ,θ T =θ R=0°, delay expansion order P=8. The figure plots the simulation results of the dual multi-tap filter structure proposed in this patent and the traditional single multi-tap filter structure with the overall self-interference prior information as input when the JNR values ​​are 25dB, 30dB, and 35dB. It can be seen from the curve that the traditional method gradually decreases with the increase of amplitude imbalance, while the method proposed in this patent can make the JCR reach its theoretical limit JNR for different amplitude imbalances, that is, the self-interference signal can be suppressed to the bottom noise level. Compared with the traditional method, the self-interference suppression effect can be significantly improved, and the greater the JNR, the greater the suppression performance improvement, indicating that the self-interference suppression architecture and method proposed in this patent can effectively eliminate the influence of amplitude imbalance.

[0064] Attachment Figure 4 The effect of phase imbalance on the self-interference suppression performance of the umbrella cover is shown in the figure when the JNR value is different. The self-interference suppression ratio JCR is used as the measurement indicator. T =β R =1,θ T =θ R , the delay expansion order P = 8. The figure plots the simulation results of the dual multi-tap filter structure proposed in this patent and the traditional method when the JNR values ​​are 25dB, 30dB, and 35dB. It can be seen from the curve that the JCR of the traditional method gradually decreases with the increase of phase imbalance, while the method proposed in this patent can make the JCR reach its theoretical limit JNR for different phase imbalances, that is, the self-interference signal can be suppressed to the bottom noise level. Compared with the traditional method, the umbrella cover self-interference suppression effect can be significantly improved, and the greater the JNR, the greater the suppression performance improvement, indicating that the self-interference suppression architecture and method proposed in this patent can effectively eliminate the influence of phase imbalance.

[0065] The foregoing description 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 construed as excluding other embodiments. Instead, the present invention 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 techniques or knowledge in the relevant field. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be protected by the appended claims.

Claims

1. A method for suppressing electromagnetic spectrum umbrella self-interference to overcome IQ imbalance, characterized by: The following steps are involved: S1. A communication transmitter within the electromagnetic spectrum umbrella generates and transmits a communication signal; S2. The canopy jammer generates and transmits a self-jamming signal; The step S2 comprises: S201. In the canopy jammer, let the baseband self-interference be u(n), which is converted to u(t) by the DAC and then up-converted. Considering the IQ imbalance at the canopy jammer, that is, there is an amplitude and phase deviation between the I-channel and Q-channel carriers generated by the oscillator. Assuming that the I-channel is in an ideal state and the phase and amplitude errors exist in the Q-channel, the self-interference signal x after up-conversion is u (t) is recorded as: Among them, f u is the carrier frequency, β T and θ T They represent the amplitude imbalance and phase imbalance at the oscillator of the umbrella jammer respectively. When there is no IQ imbalance, there is β T =1,θ T =0; S202. The self-interference signal x u (t) Transmitting through the antenna of a canopy jammer; S3. The umbrella interference suppression receiver preprocesses the received signal to obtain a digital baseband signal; The step S3 comprises: S301. At the umbrella cover self-interference suppression receiver, the signal is received through the receiving antenna, and the received signal is down-converted and sent to the ADC for processing. The obtained signal is represented as follows: Among them, the communication signal and the self-interference signal pass through L s With L u flat fading AWGN channel, g s With g u The corresponding channel fading coefficients, τ s With τ u They represent the normalized time delay introduced by the multipath effect that still exists after the communication signal and the self-interference signal are time synchronized. w′(n) is the AWGN signal, which is independent of the communication signal and the self-interference signal. Considering the IQ imbalance at the receiver, the received signal is down-converted. The received signal is multiplied by the down-converted signal and integrated to filter out the high-frequency component. The received signal after down-conversion is: y(n)=y u (n)+y s (n)+w(n) y u (n) is the self-interference signal obtained by down-conversion processing, and its expression is: in, and is the composite channel coefficient corresponding to the original self-interference component and the image component, and the expression is: Among them, β R and θ R They represent the amplitude imbalance and phase imbalance of the receiver oscillator suppressed by the umbrella cover self-interference respectively; S4. The umbrella interference suppression receiver converts the IQ imbalance and delay error into the model coefficients of the multi-tap filter; The step S4 comprises: S401. Convert the IQ imbalance and delay spread into the form of the product of the coefficient and the self-interference sequence: In the self-interference signal after down-conversion, y u (t) From the self-interference sequence u(n) and the conjugate term u * (n), since u(n) and u * (n) is correlated, assuming that the imaginary and real parts of the self-interference are independent and identically distributed, the received self-interference signal is converted into the expression of the real and imaginary parts of u(n), that is, S402. Use the ideal fractional delay filter to expand the delay spread introduced by the multipath effect, that is: Where 2P+1 is the filter order, and the ideal fractional delay filter coefficient is: Therefore, the expression of the self-interference signal after time delay expansion is: S403. Combine the coefficients before the real and imaginary components of the self-interference signal into one term, and obtain: The coefficient expression is: S5. The umbrella interference suppression receiver estimates the model coefficients of the multi-tap filter; S6. The umbrella cover interference suppression receiver reconstructs the self-interference signal to suppress the umbrella cover self-interference and obtain the communication receiving signal.

2. The electromagnetic spectrum umbrella self-interference suppression method for overcoming IQ imbalance according to claim 1, characterized in that: The step S1 comprises: S101. In the communication transmitter, the baseband communication signal is s(n), which is converted to s(t) by the DAC and then up-converted. Without considering the IQ imbalance of the transmitter, the RF communication signal after upconversion 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, f s is the carrier frequency; S102. The radio frequency communication signal x s (t) Transmission via the antenna of a communications transmitter.

3. The electromagnetic spectrum umbrella self-interference suppression method for overcoming IQ imbalance according to claim 2, characterized in that: The step S5 comprises: S501. Two multi-tap filters are set at the umbrella cover self-interference suppression receiver, and the inputs are the real and imaginary components of the signal after analog-to-digital conversion and down-conversion. The output signals of the two multi-tap filters are combined to obtain a self-interference reconstruction signal; S502. Calculate the tap coefficient: (1) The tap coefficient is expressed as a [2×(2P+1)]×1-dimensional vector, that is: z=[a -P ,...,a0,...,a P ,b -P ,...,b0,...,b P ] T Element a in the coefficient vector i is the i+P+1 tap coefficient in the first multi-tap filter, element b i is the i+P+1th tap coefficient in the second multi-tap filter; (2) will u i (n) and u q (n) Input the multi-tap filter to obtain the reconstructed signal: in Oh n =[Ω(1),Ω(2),...,Ω(n)] T Ω(n)=[u i (n+P),...,u i (n),...,u i (n-P),u q (n+P),...,u q (n),...,u q (n-P)] T (3) The calculation formula of the coefficient vector z estimation value is obtained by using the least squares criterion, with the minimum error square sum as the optimization goal, and the error is the actual received self-interference signal y at the previous n moments u,n The signal reconstructed by the self-interference prior information of the umbrella cover self-interference suppression receiver The difference between , we get: in, Represents the coefficient vector estimated by the data of the previous n moments, and defines two new variables as R n =Ω n T Ω n ,d n =Ω n T y u,n ; (4) Using the recursive least squares algorithm to estimate the coefficients, the recursive relationship is: Set the initialization value to: Where δ is a small positive number and I is the identity matrix; (5) Iterate according to step (4). When the set number of iterations is reached, the final estimation result is recorded as the coefficient vector estimate.

4. The electromagnetic spectrum umbrella self-interference suppression method for overcoming IQ imbalance according to claim 3, characterized in that: The step S6 comprises: will u i (n) and u q (n) Input the multi-tap filter to obtain the self-interference reconstruction signal: The reconstructed self-interference signal is subtracted from the original received signal y(n) to obtain the residual received signal after interference suppression as the communication received signal.

5. An electromagnetic spectrum umbrella self-interference suppression architecture for overcoming IQ imbalance, employing the method of any one of claims 1 to 4, characterized in that: include: A communication transmitter, used to generate and transmit communication signals; A canopy jammer, used to generate and transmit self-jamming signals; The umbrella interference suppression receiver is used to preprocess the received signal to obtain a digital baseband signal, then convert the IQ imbalance and delay error into the model coefficients of the multi-tap filter, estimate the self-interference model coefficients, and reconstruct the self-interference signal to perform umbrella self-interference suppression and obtain the communication reception signal.

Images