Method and device for separating mixed vortex electromagnetic wave signal

Abstract

Disclosed in the present invention is a method applicable to a mixed vortex wave signal comprising nonlinear vortex electromagnetic waves and linear vortex electromagnetic waves. The method comprises: first, by means of variable-mode cyclic IFFT, separating, from a full-aperture sampled and received vector of a mixed vortex wave beam, information carried by a linear vortex electromagnetic wave beam; then, by means of the information carried by the linear vortex electromagnetic wave beam and a Fourier series corresponding to a mode, constructing a linear vortex wave signal component in the full-aperture sampled and received vector of the mixed vortex wave beam, and subtracting the linear vortex wave signal vector from the full-aperture sampled and received vector of the mixed vortex electromagnetic wave beam to estimate a nonlinear vortex wave signal vector; and then, performing conjugate cyclic ZC transform on the estimated nonlinear vortex wave signal vector to obtain information carried by the nonlinear vortex electromagnetic wave beam. Also disclosed is a device for implementing the method for separating a mixed vortex wave signal comprising nonlinear vortex electromagnetic waves and linear vortex electromagnetic waves.

Description

Method and apparatus for separating hybrid vortex electromagnetic wave signals Technical Field

[0001] This invention relates to hybrid vortex electromagnetic wave signal processing in an integrated system of vortex electromagnetic wave communication-sensing-anti-interference, and belongs to the fields of communication signal processing technology and radar signal processing technology. Background Technology

[0002] The theory and technology of improving channel capacity in wireless communication systems is a perennial research topic in the field of communications. According to Shannon's channel capacity theory, the technology of obtaining the capacity of a wireless communication system from the four dimensions of signal frequency, time, codeword, and space cannot effectively support the future capacity requirements of wireless communication. Therefore, researchers have attempted to further explore the theory and technology of improving system channel capacity by using another inherent physical quantity carried by electromagnetic waves—orbital angular momentum (OAM)—to carry information. Studies have shown that the orthogonality of the wavefront phases of different modes of OAM electromagnetic waves allows them to share channel transmission simultaneously. Because the wavefront phases of OAM electromagnetic waves exhibit a vortex-like distribution, they are scientifically termed vortex electromagnetic waves.

[0003] Vortex electromagnetic waves were first discovered experimentally by Dutch physicist L. Allen in 1992. In 2007, Swedish scholars Thidé Bo et al. introduced them into the microwave band and experimentally verified that the channel-sharing capability of vortex electromagnetic waves can improve the system's channel capacity without increasing the system bandwidth.

[0004] Literature review indicates that transmitting mode-multiplexed vortex electromagnetic waves using a uniform circular array (UCA) is feasible and convenient in the field of radio frequency (RF). The UCA method for generating vortex electromagnetic waves belongs to the category of phase-shifting methods for array element excitation signals. Research shows that the sequences used for phase shifting of UCA array element excitation signals can be divided into two categories: periodic sequences and aperiodic sequences on a unit circle in the complex plane. Typical representatives are the Discrete Fourier Sequence (DFS) sequence and the ZC sequence, respectively. The wavefront phase topology of the vortex electromagnetic waves generated by the DFS has… Therefore, the vortex electromagnetic waves generated by DFS are called linear vortex electromagnetic waves; the wavefront phase topology of vortex electromagnetic waves generated by ZC sequences is no longer simple. The linear relationship means that the vortex electromagnetic waves generated by the ZC sequence are called nonlinear vortex electromagnetic waves.

[0005] Since the ZC sequence and DFS are separable, it is feasible to use UCA to sample and receive the mixed vortex electromagnetic wave beam of the propagating linear vortex electromagnetic wave and nonlinear vortex electromagnetic wave at the receiving end and separate the signals.

[0006] As is well known, the DFS (Diverterless Field-Switch) sequence possesses excellent central and axial symmetry on a unit circle in the complex plane. Linear vortex electromagnetic wave beams based on DFS phase shifts exhibit a hollow, divergent shape, and the divergence of different mode linear vortex electromagnetic wave beams is coupled with mode l. The ZC (Zero-Cell) sequence, however, has less symmetry in the complex plane than the DFS sequence, and nonlinear vortex electromagnetic wave beams phase-shifted by the ZC sequence are not hollow. Utilizing the periodic cyclic shift characteristics of the ZC sequence, a cluster of mode-multiplexed nonlinear vortex electromagnetic wave beams can be generated, and this cluster of nonlinear vortex electromagnetic wave beams exhibits a coaxial circular cyclic rotation relationship in space. This provides natural conditions for the uniform convergence of nonlinear vortex electromagnetic wave beams.

[0007] In the integrated communication-sensing-anti-interference system using vortex electromagnetic waves, target sensing is achieved by utilizing different coverage areas of linear vortex electromagnetic wave beams, while information transmission is performed using nonlinear vortex electromagnetic waves with a limited receiving aperture. In summary, based on signal processing theory and complex sequences, the inventors (or group) have proposed a hybrid vortex wave signal separation method combining nonlinear and linear vortex electromagnetic waves, which can support the realization of an integrated communication-sensing-anti-interference wireless communication system based on vortex electromagnetic waves.

[0008] Summary of the Invention

[0009] This invention aims to solve the problem of separating hybrid vortex wave signals of nonlinear vortex electromagnetic waves and linear vortex electromagnetic waves, so as to support the realization of an integrated system of vortex electromagnetic wave communication-sensing-anti-interference.

[0010] Further features and aspects of the invention are described in the following detailed embodiments. Attached Figure Description

[0011] Figure 1 is a summary drawing of the present invention.

[0012] Figure 2 is a schematic diagram of the physical device of the separation method for hybrid vortex electromagnetic wave signals according to the present invention, wherein (1) is a full aperture sampling and receiving array for hybrid vortex electromagnetic waves, (2) is a cyclic IFFT transform, (3) is a mode controller, (4) is a summer, (5) is a Fourier sequence phase shifter, (6) is a differencer, and (7) is a conjugate cyclic ZC transformer. Detailed Implementation

[0013] The separation method for hybrid vortex electromagnetic wave signals involves uniformly sampling the hybrid vortex electromagnetic wave beam across the entire aperture using a UCA antenna with N array elements, and the responses of the N receiving array elements constitute a receiving response vector.

[0014] Perform a cyclic IFFT operation on the received response vector for mode l, and sum the results of N cyclic IFFT operations to obtain the user information carried by the linear vortex electromagnetic wave of mode l. Subtract the user information carried by the linear vortex electromagnetic wave of mode l from the received response vector to obtain the nonlinear vortex electromagnetic wave received vector. Perform a conjugate cyclic ZC transform on the nonlinear vortex electromagnetic wave received vector to obtain the user information carried by the nonlinear vortex electromagnetic wave.

[0015] The method for separating the hybrid vortex electromagnetic wave signal includes the following steps:

[0016] (a) The received vector y = y = N elements of the receiving antenna. FS +y ZC ={y(0),y(1),…,y(i),…,y(N-1)}, where the response y(i) of the i-th element is,

[0017] Among them, y FS (i) represents the linear vortex electromagnetic wave signal component, y ZC (i) represents the nonlinear vortex electromagnetic wave signal component. The information carried by the mode l linear vortex electromagnetic wave Let be the channel fading function of the mode l linear vortex electromagnetic wave. The information carried by the modal nonlinear vortex electromagnetic wave. Let be the channel fading function of the mode l nonlinear vortex electromagnetic wave;

[0018] (b) Take l0∈{0,1,…,N-1}, and construct a discrete Fourier sequence set. Depend on For the received response vector y = y FS +y ZC Perform the first IFFT operation.

[0019] (c) For discrete Fourier sequence sets One cyclic shift yields the discrete Fourier sequence set. Depend on For the received response vector y = y FS +y ZC Perform a second IFFT operation.

[0020] (d) For discrete Fourier sequence sets One cyclic shift yields the discrete Fourier sequence set. Depend on For the received response vector y = y FS +yZC Perform the third IFFT operation.

[0021] (e) Following the method in step (d), the discrete Fourier sequence set can be obtained. …,and Depend on For the received response vector y = y FS +y ZC The results of performing the fourth, fifth, ..., N-1th IFFT operations are as follows:

[0022] (f) Add formulas (2), (3), (4) and (5) together.

[0023] In formula (6) It is the channel attenuation constant. To extract the information carried by the linear vortex electromagnetic wave beam of mode l0, mode l0 traverses once in the linear vortex electromagnetic wave mode set {0,1,…,N-1}, thus enabling the separation of the information carried by the linear vortex electromagnetic wave from the sampled and received signal of the mixed vortex electromagnetic wave beam.

[0024] (g) Information carried by linear vortex electromagnetic waves The Fourier sequence set corresponding to the modes l = 0, 1, ..., N-1 of linear vortex electromagnetic waves Construct signal

[0025] (h) The constructed signal is subtracted from the received vector y formed by the N-element response of the receiving antenna.

[0026] (i) From the ZC sequence right Perform conjugate cyclic ZC transform.

[0027] in, To receive the information carried by the nonlinear vortex electromagnetic wave beam of mode l in vector y.

Claims

1. A method for separating hybrid vortex electromagnetic wave signals, characterized in that, A receiving antenna with N array elements uniformly samples the hybrid vortex electromagnetic wave beam across the entire aperture. The responses of the N receiving array elements constitute the receiving response vector. A cyclic IFFT operation on mode l is performed on the receiving response vector, and the results of the N cyclic IFFT operations are summed to obtain the information carried by the mode l linear vortex electromagnetic wave beam. The information carried by the mode l linear vortex electromagnetic wave is then subtracted from the receiving response vector to obtain the sampling vector of the nonlinear vortex electromagnetic wave beam. A conjugate cyclic ZC transform is performed on the received vector of the nonlinear vortex electromagnetic wave beam obtained by subtracting the calculated nonlinear vortex electromagnetic wave beam to obtain the information carried by the nonlinear vortex electromagnetic wave beam. The method for separating the hybrid vortex electromagnetic wave signal includes the following steps: (a) The received vector y = y = N elements of the receiving antenna. FS +y ZC ={y(0),y(1),…,y(i),…,y(N-1)}, where the response y(i) of the i-th element is, Among them, y FS (i) represents the linear vortex electromagnetic wave signal component, y ZC (i) represents the nonlinear vortex electromagnetic wave signal component. The information carried by the mode l linear vortex electromagnetic wave Let be the channel fading function of the mode l linear vortex electromagnetic wave. The information carried by the modal nonlinear vortex electromagnetic wave. Let be the channel fading function of the mode l nonlinear vortex electromagnetic wave; (b) Take l0∈{0,1,…,N-1}, and construct a discrete Fourier sequence set. Depend on For the received response vector y = y FS +y ZC Perform the first IFFT operation. (c) For discrete Fourier sequence sets One cyclic shift yields the discrete Fourier sequence set. Depend on For the received response vector y = y FS +y ZC Perform a second IFFT operation. (d) For discrete Fourier sequence sets One cyclic shift yields the discrete Fourier sequence set. Depend on For the received response vector y = y FS +y ZC Perform the third IFFT operation. (e) Following the method in step (d), the discrete Fourier sequence set can be obtained. …,and Depend on For the received response vector y = y FS +y ZC The results of performing the fourth, fifth, ..., N-1th IFFT operations are as follows: (f) Add formulas (2), (3), (4) and (5) together. In formula (6) It is the channel attenuation constant. To extract the information carried by the linear vortex electromagnetic wave beam of mode l0, mode l0 traverses once in the linear vortex electromagnetic wave mode set {0,1,…,N-1}, thus enabling the separation of the information carried by the linear vortex electromagnetic wave from the sampled and received signal of the mixed vortex electromagnetic wave beam. (g) Information carried by linear vortex electromagnetic waves The Fourier sequence set corresponding to the modes l = 0, 1, ..., N-1 of linear vortex electromagnetic waves Construct signal (h) The constructed signal is subtracted from the received vector y formed by the N-element response of the receiving antenna. (i) From the ZC sequence right Perform conjugate cyclic ZC transform. in, To receive the information carried by the nonlinear vortex electromagnetic wave beam of mode l in vector y.

2. A physical apparatus for implementing the separation method for hybrid vortex electromagnetic wave signals as described in claim 1, characterized in that: The full-aperture sampling and receiving vector of the hybrid vortex electromagnetic wave beam is subjected to a variable-mode cyclic IFFT transform, and the output of the variable-mode cyclic IFFT transform is grouped and summed to obtain the information carried by the linear vortex electromagnetic waves of different modes. The linear vortex wave signal components in the full-aperture sampling and receiving vector of the hybrid vortex electromagnetic wave beam are estimated by the information carried by the linear vortex electromagnetic waves of each mode and the corresponding mode Fourier sequence. The linear vortex wave signal components are subtracted from the full-aperture sampling and receiving vector of the hybrid vortex electromagnetic wave beam to obtain the nonlinear vortex electromagnetic wave beam sampling and receiving vector. The calculated nonlinear vortex electromagnetic wave beam sampling and receiving vector is subjected to a conjugate cyclic ZC transform by a ZC sequence to obtain the information carried by the nonlinear vortex electromagnetic wave beam in the full-aperture sampling and receiving vector of the hybrid vortex electromagnetic wave beam.

3. The physical apparatus for the separation method of hybrid vortex electromagnetic wave signals according to claim 2 further includes: The system comprises a hybrid vortex electromagnetic wave full aperture sampling receiver array (1), a cyclic IFFT transformer (2), a mode controller (3), a summer (4), a Fourier sequence phase shifter (5), a differencer (6), and a ZC sequence circular correlator (7). The output of the hybrid vortex electromagnetic wave full aperture sampling receiver array (1) is connected to the input of the cyclic IFFT transformer (2) and the input of the differencer (6). The output of the cyclic IFFT transformer (2) is connected to the input of the summer (4). The output of the summer (4) is connected to the input of the Fourier sequence phase shifter (5). The output of the Fourier sequence phase shifter (5) is connected to the input of the differencer (6). The output of the differencer (6) is connected to the input of the ZC sequence circular correlator (7). The mode controller (3) controls the synchronization and change of the modes of the cyclic IFFT transformer (2) and the Fourier sequence phase shifter (5).

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