Pilot blind estimation method and device of OFDM signal applied to electronic reconnaissance

Abstract

The application discloses an OFDM signal pilot blind estimation method and device applied to electronic reconnaissance, which comprises the following steps: performing FFT on M frames of OFDM signals after blind time-frequency synchronization, so as to obtain OFDM frequency domain data of the M frames; recombining frequency domain data of different frames, different OFDM symbols and the same frequency points, so as to obtain N two-dimensional arrays Z; for each two-dimensional array Z, selecting one vector Y from M vectors Y and respectively performing conjugate multiplication operation on the selected vector Y and the M-1 vectors Y which are not selected, so as to obtain M-1 vectors C; for each frequency point, accumulating the M-1 vectors C of the frequency point, and performing modulus operation on the accumulated items, so as to obtain a one-dimensional vector corresponding to the frequency point; for each frequency point, accumulating the one-dimensional vector corresponding to the frequency point, so as to obtain a correlation value of the frequency point; and through threshold value judgment on the correlation value, pilot blind estimation is realized. The modulus operation on the accumulated items effectively reduces the influence of frequency offset on pilot blind estimation.

Description

Technical Field

[0001] This invention belongs to the field of communication technology, specifically relating to a method and apparatus for blind estimation of OFDM (Orthogonal Frequency Division Multiplexing) signals applied in electronic reconnaissance. Background Technology

[0002] Non-cooperative communication is a special mode in the field of communications. Its characteristic lies in the fact that, without authorization, a third party involved in the communication process can blindly estimate the basic parameters of the signal and complete steps such as blind time-frequency synchronization and blind channel equalization, ultimately achieving blind demodulation of the signal. In civilian communications, relevant regulatory departments, in order to ensure the rational use of spectrum space and a healthy communication environment, must monitor and control free-space signals, requiring the ability to blindly identify communication signals without any prior information. In military communications, only the correct identification and demodulation of unknown signals can enable the reconnaissance of enemy communication systems. Non-cooperative communication has many potential applications in both military and civilian fields, such as satellite communications and cognitive radio. Therefore, research on the receiving and processing technology of non-cooperative communication systems has significant practical application value.

[0003] As OFDM technology becomes increasingly widely used, its application in non-cooperative communication systems is also developing rapidly. However, the basic parameters of OFDM systems are not only numerous, but their estimation is also highly complex and difficult. In today's rapidly evolving technological society, research on the reception and processing technology of non-cooperative OFDM signals is of great significance, whether from the perspective of national defense security and development, military reconnaissance, or communication environment supervision.

[0004] Receiving non-cooperative OFDM signals requires a series of steps, including received signal preprocessing, blind parameter estimation, blind time-frequency synchronization, and blind channel equalization, before correct demodulation can be achieved. Among these, blind parameter estimation is the prerequisite and foundation for all other processing techniques; only with the correct signal parameters can subsequent synchronization and equalization be meaningful.

[0005] One crucial parameter to estimate when performing blind parameter estimation for OFDM signals is the pilot signal. Pilot signals play a vital role in subsequent channel estimation. In radar and satellite communications, pilot blind estimation techniques can effectively address complex electromagnetic environments, improving the accuracy and efficiency of signal processing. In spectrum-sharing environments where multiple communication systems share the same spectrum resources, pilot blind estimation techniques can improve spectrum utilization efficiency and reduce interference. Therefore, researching pilot blind estimation techniques can provide significant support for the efficiency, reliability, and flexibility of blind demodulation systems for non-cooperative signals.

[0006] Currently, there are numerous research algorithms for blind parameter estimation of OFDM signals, but there are few methods for blind pilot estimation of OFDM signals, and existing methods suffer from low accuracy in blind pilot estimation. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, this invention provides a method and apparatus for blind estimation of OFDM signal pilots in electronic reconnaissance.

[0008] The technical problem to be solved by this invention is achieved through the following technical solution:

[0009] In a first aspect, the present invention provides a method for blind estimation of OFDM signal pilots applied in electronic reconnaissance, comprising:

[0010] Perform an FFT on the OFDM signal after blind time-frequency synchronization of M frames to obtain the OFDM frequency domain data of M frames; where each OFDM frequency domain data includes U OFDM symbols;

[0011] Frequency domain data from different frames, different OFDM symbols, and the same frequency point are recombined to obtain N two-dimensional arrays Z; wherein, the two-dimensional array Z includes M vectors Y; each vector Y includes U frequency domain data;

[0012] For each two-dimensional array Z, select one vector Y from M vectors Y and perform conjugate multiplication with each of the M-1 unselected vectors Y to obtain M-1 vectors C;

[0013] For each frequency point, accumulate its M-1 vectors C, and calculate the modulus of the accumulated terms to obtain the one-dimensional vector corresponding to that frequency point;

[0014] For each frequency point, the corresponding one-dimensional vector is accumulated to obtain the correlation value of that frequency point;

[0015] By thresholding the correlation values ​​of N frequency points, pilot blind estimation of OFDM signals can be achieved.

[0016] Optionally, there is a one-to-one correspondence between the M vectors Y and the OFDM frequency domain data of the M frames;

[0017] For each two-dimensional array Z, select one vector Y from the M vectors Y and perform conjugate multiplication with each of the M-1 unselected vectors Y to obtain M-1 vectors C, including:

[0018] For each two-dimensional array Z, select the vector Y corresponding to the OFDM frequency domain data of the first frame from M vectors Y as the local sequence;

[0019] The local sequence is multiplied by the conjugate of each of the M-1 unselected vectors Y to obtain M-1 vectors C.

[0020] Optionally, by thresholding the correlation values ​​of N frequency points, blind estimation of OFDM signal pilots can be achieved, including:

[0021] The correlation values ​​of N frequency points are normalized to obtain the normalized correlation values ​​of N frequency points;

[0022] Frequency points where the normalized correlation value exceeds a preset threshold are identified as pilot locations to achieve blind estimation of OFDM signal pilots.

[0023] Optionally, the OFDM signal pilot blind estimation method further includes:

[0024] The two-dimensional array Z corresponding to the frequency point at the pilot position is obtained; the reciprocal V of the magnitude variance of the two-dimensional array Z in the frame dimension is calculated. m The inverse of the variance of the magnitude in the sign dimension, V t ;

[0025] According to V m and V t The pilot value corresponding to the pilot position is determined to be either a pseudo-random value or a fixed value.

[0026] Optional, according to V m and V t Determining whether the pilot value corresponding to the pilot position is a pseudo-random value or a fixed value includes:

[0027] When V t Greater than V m At that time, the pilot value corresponding to the pilot position is determined to be a fixed value;

[0028] When V m Greater than V t When the pilot value corresponding to the pilot position is determined to be a pseudo-random value.

[0029] Secondly, the present invention provides a pilot blind estimation device for OFDM signals applied in electronic reconnaissance, comprising:

[0030] The FFT module is used to perform FFT on the OFDM signal after blind time-frequency synchronization of M frames to obtain the OFDM frequency domain data of M frames; wherein each OFDM frequency domain data includes U OFDM symbols;

[0031] The frequency domain data reassembly module is used to reassemble frequency domain data from different frames, different OFDM symbols, and the same frequency point to obtain N two-dimensional arrays Z; wherein, the two-dimensional array Z includes M vectors Y; each vector Y includes U frequency domain data.

[0032] The conjugate multiplication module is used to select one vector Y from M vectors Y for each two-dimensional array Z and perform conjugate multiplication with the M-1 unselected vectors Y respectively to obtain M-1 vectors C;

[0033] The one-dimensional vector acquisition module is used to accumulate M-1 vectors C for each frequency point, and calculate the modulus of the accumulated terms to obtain the one-dimensional vector corresponding to that frequency point.

[0034] The correlation value acquisition module is used to accumulate the one-dimensional vector corresponding to each frequency point to obtain the correlation value of that frequency point;

[0035] The threshold judgment module is used to perform threshold judgment on the correlation values ​​of N frequency points to realize pilot blind estimation of OFDM signals.

[0036] Optionally, there is a one-to-one correspondence between the M vectors Y and the OFDM frequency domain data of the M frames;

[0037] The conjugate multiplication operation module is specifically used to select the vector Y corresponding to the OFDM frequency domain data of the first frame from M vectors Y for each two-dimensional array Z as a local sequence; and to perform conjugate multiplication operations on the local sequence and the M-1 unselected vectors Y respectively to obtain M-1 vectors C.

[0038] Optionally, the threshold judgment module is specifically used to normalize the correlation values ​​of N frequency points to obtain normalized correlation values ​​of N frequency points; and to determine the frequency points whose normalized correlation values ​​exceed a preset threshold as pilot positions, so as to realize pilot blind estimation of OFDM signals.

[0039] Optionally, the OFDM signal pilot blind estimation device further includes a pilot value determination module;

[0040] The pilot value determination module is used to obtain a two-dimensional array Z corresponding to the frequency point corresponding to the pilot position; and to calculate the reciprocal V of the magnitude variance of the two-dimensional array Z in the frame dimension. m The inverse of the variance of the magnitude in the sign dimension, V t According to V m and V t The pilot value corresponding to the pilot position is determined to be either a pseudo-random value or a fixed value.

[0041] Optionally, in the pilot value determination module, based on V m and V t Determining whether the pilot value corresponding to the pilot position is a pseudo-random value or a fixed value includes:

[0042] When V t Greater than V mAt that time, the pilot value corresponding to the pilot position is determined to be a fixed value;

[0043] When V m Greater than V t When the pilot value corresponding to the pilot position is determined to be a pseudo-random value.

[0044] Thirdly, the present invention provides an electronic device, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus;

[0045] Memory, used to store computer programs;

[0046] When the processor executes the program stored in the memory, it implements the steps described in any of the OFDM signal pilot blind estimation methods.

[0047] Fourthly, the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the above-described OFDM signal pilot blind estimation methods applied in electronic reconnaissance.

[0048] In another aspect of the invention, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to perform the steps of any of the above-described OFDM signal pilot blind estimation methods applied in electronic reconnaissance.

[0049] This invention provides a pilot blind estimation method for OFDM signals applied in electronic reconnaissance. By accumulating M-1 vectors C for each frequency point and then calculating the modulus of the accumulated terms, the impact of frequency offset on pilot blind estimation can be effectively reduced. Even with a large residual frequency offset, high-accuracy pilot blind estimation can still be performed, and the correctness of the pilot blind estimation is unaffected by the data and pilot modulation method of the OFDM signal at the transmitting end.

[0050] Furthermore, since the frequency domain data of different frames, different OFDM symbols, and the same frequency point are recombined, N two-dimensional arrays Z are obtained by making full use of the characteristics of OFDM signals in the frequency and time domains. Therefore, even when the amount of OFDM signal data received is low, pilot blind estimation of OFDM signals can still be performed.

[0051] The present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0052] Figure 1 This is a flowchart illustrating a method for blind estimation of OFDM signal pilots in electronic reconnaissance, provided by an embodiment of the present invention.

[0053] Figure 2 This is a schematic diagram of the frequency domain data reconstruction process provided in an embodiment of the present invention;

[0054] Figure 3 This is a schematic diagram illustrating the conjugate multiplication operation and the process of calculating related values ​​provided in an embodiment of the present invention;

[0055] Figure 4 This is a schematic diagram illustrating threshold determination of normalized correlation values ​​at N frequency points provided in an embodiment of the present invention;

[0056] Figure 5 This is a schematic diagram illustrating the correct probability of pilot estimation under different data modulation and pilot modulation methods;

[0057] Figure 6 This is a schematic diagram of the frequency offset resistance range;

[0058] Figure 7 This is a schematic diagram illustrating the probability of correct pilot position estimation under different frame numbers and different signal-to-noise ratios;

[0059] Figure 8 This is a schematic diagram of the structure of an OFDM signal pilot blind estimation device applied in electronic reconnaissance, provided by an embodiment of the present invention;

[0060] Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0061] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0062] To address the issue of low accuracy in current methods for pilot blind estimation of OFDM signals, this invention provides a method for OFDM signal pilot blind estimation applied in electronic reconnaissance. (See [link to relevant documentation]). Figure 1 , Figure 1 This is a flowchart illustrating a method for blind estimation of OFDM signal pilots in electronic reconnaissance, provided by an embodiment of the present invention. The method specifically includes the following steps:

[0063] Step S101: Perform FFT (Fast Fourier Transform) on the OFDM signal after blind time-frequency synchronization of M frames to obtain OFDM frequency domain data of M frames; wherein each OFDM frequency domain data includes U OFDM symbols.

[0064] First, after acquiring the M-frame OFDM signal, it is necessary to preprocess the OFDM signal to obtain the M-frame blind time-frequency synchronized OFDM signal. The specific preprocessing process is as follows:

[0065] Blind estimation of the time and frequency domain parameters of the OFDM signal yields its basic structural information. Specifically, this basic structural information may include the FFT length of the OFDM symbol, the cyclic prefix (CP) length, and the number of OFDM symbols in each frame.

[0066] Then, symbol blind synchronization and carrier blind synchronization are performed on the OFDM signal to obtain the M-frame blind time-frequency synchronized OFDM signal. Symbol blind synchronization can accurately find the starting position of the OFDM symbol to ensure correct demodulation of the signal. Carrier blind synchronization can correct frequency offset to ensure synchronization of each OFDM signal in the frequency domain.

[0067] By performing an FFT operation on the OFDM signal after blind time-frequency synchronization of M frames, the time-domain OFDM signal can be converted into a frequency-domain representation, thus obtaining the OFDM frequency-domain data of M frames. Each OFDM frequency-domain data includes U OFDM symbols.

[0068] Step S102: Reassemble the frequency domain data of different frames, different OFDM symbols, and the same frequency point to obtain N two-dimensional arrays Z; wherein, the two-dimensional array Z includes M vectors Y; each vector Y includes U frequency domain data.

[0069] See Figure 2 , Figure 2 This is a schematic diagram of the frequency domain data reconstruction process provided in an embodiment of the present invention. First, the data of the same frame is processed. Specifically, the data is extracted according to the frequency domain direction, that is, specific frequency points are selected in the frequency domain direction. Figure 2 The left side represents the OFDM frequency domain data of frame M. Each two-dimensional array Z represents time domain data (OFDM symbols) horizontally and frequency points vertically. The frequency domain data of the same frequency point in each two-dimensional array Z are combined. Assuming there are U OFDM symbols in each frame, there will be U frequency domain data points of the same frequency point in each frame. Therefore, for each frame, a one-dimensional vector Y containing U elements can be formed. (See [reference]). Figure 2 Right side.

[0070] Taking the first frame (m=1) as an example, the resulting vector Y 1 for:

[0071]

[0072] Among them, Y m Represents the vector Y formed in the m-th frame; Let u represent the u-th frequency domain data in the vector Y formed by the m-th frame at the n-th frequency point. u∈U.

[0073] Reassembling the other frames using the same method yields a two-dimensional array Z of size M*U. Here, M represents the number of frames, and U represents the number of OFDM symbols in each frame, which is also the amount of frequency domain data.

[0074] For example, if the two-dimensional array Z at the first frequency point is Z1, then Z1 is represented as:

[0075]

[0076] Among them, the M vectors Y in Z1 include Y 1 Y 2 …Y M .

[0077] By recombining frequency domain data from different frames, different OFDM symbols, and the same frequency point, multiple two-dimensional arrays Z can be obtained. If the number of frequency points is N, then N two-dimensional arrays Z can be obtained, which can be represented as [Z1, ..., Z2]. N ] T T represents the transpose of the matrix. Each two-dimensional array corresponds to the frequency domain data at the same frequency point.

[0078] Step S103: For each two-dimensional array Z, select one vector Y from the M vectors Y and perform conjugate multiplication with the M-1 unselected vectors Y respectively to obtain M-1 vectors C.

[0079] In this embodiment of the invention, each two-dimensional array Z includes M vectors Y. One vector Y is selected from the M vectors Y as the local sequence, and a reference vector is determined to facilitate the conjugate multiplication operation. See also Figure 3 , Figure 3 This is a schematic diagram illustrating the conjugate multiplication operation and related value calculation process provided in this embodiment of the invention. For a two-dimensional array Z, the i-th vector Y is selected as the local sequence, such as the i=M-th vector Y. The M-th vector Y is then multiplied by its conjugate with each of the other M-1 unselected vectors Y. Conjugate multiplication refers to multiplying each element of one vector by the conjugate element of another vector, resulting in M-1 vectors C. The M-1 vectors C include Ci... n (1) C n (2)…C n (M-1). Where n represents the number of frequency points, Figure 3 () * Indicates conjugate.

[0080] Step S104: For each frequency point, accumulate its M-1 vectors C, and calculate the modulus of the accumulated terms to obtain the one-dimensional vector corresponding to that frequency point.

[0081] After the conjugate multiplication operation, each frequency point corresponds to M-1 vectors C. For each frequency point, its M-1 vectors C are accumulated, and the modulus of the accumulated terms is taken to obtain:

[0082]

[0083] Among them, C n (m) represents the m-th vector C at the n-th frequency point; n∈N; |·| represents the modulus operation.

[0084] By performing the above operation on N frequency points, we can obtain a one-dimensional vector corresponding to each of the N frequency points.

[0085] Step S105: For each frequency point, accumulate the one-dimensional vector corresponding to that frequency point to obtain the correlation value of that frequency point.

[0086] See Figure 3 For each frequency point, the correlation value is obtained by summing each element of the corresponding one-dimensional vector. This correlation value reflects the similarity of OFDM signals at different frequency points. The correlation value can be calculated using the following formula:

[0087]

[0088] Where K(n) represents the correlation value at the nth frequency point.

[0089] By calculating the correlation value for each frequency point, the correlation values ​​for N frequency points can be obtained.

[0090] Step S106: By thresholding the correlation values ​​of N frequency points, pilot blind estimation of OFDM signal is achieved.

[0091] In this embodiment of the invention, the correlation values ​​at N frequency points can reflect the similarity of OFDM signals at different frequency points. The larger the correlation value, the higher the similarity. Therefore, the similarity of OFDM signals at different frequency points can be used to perform pilot blind estimation of OFDM signals based on correlation values ​​exceeding a preset threshold.

[0092] In this embodiment of the invention, by accumulating M-1 vectors C for each frequency point and then calculating the modulus of the accumulated terms, the impact of frequency offset on pilot blind estimation can be effectively reduced. Even with a large residual frequency offset, high-accuracy pilot blind estimation can still be performed, and the correctness of the pilot blind estimation is unaffected by the data of the OFDM signal at the transmitting end and the pilot modulation method.

[0093] Furthermore, since the frequency domain data of different frames, different OFDM symbols, and the same frequency point are recombined, N two-dimensional arrays Z are obtained by making full use of the characteristics of OFDM signals in the frequency and time domains. Therefore, even when the amount of OFDM signal data received is low, pilot blind estimation of OFDM signals can still be performed.

[0094] In one implementation, there is a one-to-one correspondence between M vectors Y and M frames of OFDM frequency domain data; for each two-dimensional array Z, one vector Y is selected from the M vectors Y and multiplied by the conjugate of each of the unselected M-1 vectors Y to obtain M-1 vectors C, including:

[0095] For each two-dimensional array Z, select the vector Y corresponding to the OFDM frequency domain data of the first frame from M vectors Y as the local sequence;

[0096] Perform conjugate multiplication on the local sequence and each of the M-1 unselected vectors Y to obtain M-1 vectors C.

[0097] In this embodiment of the invention, there is a one-to-one correspondence between M vectors Y and M frames of OFDM frequency domain data. Each two-dimensional array Z includes M vectors Y. One vector Y is selected from the M vectors Y as the local sequence, and a reference vector is determined to facilitate the conjugate multiplication operation. Again, taking the aforementioned Z1 as an example, Z1 is represented as:

[0098]

[0099] The vector Y corresponding to the OFDM frequency domain data of the first frame in Z1 is selected as the local sequence, denoted as Y. 1 Y 1 Compared with other vectors Y in Z1, namely Y 2 …Y M Performing conjugate multiplication, we get c(m) = (Y) 1 ) * ×Y m Where c(m) represents the m-th vector C; (Y 1 ) * Y represents 1 The conjugate of Y; m Let Y represent the m-th vector; m∈M-1.

[0100] Finally, the resulting M-1 vectors C are:

[0101]

[0102] in, This represents the frequency domain data in the U vectors Y in the first frame at the first frequency point; This represents the frequency domain data in the U vector Y in the (m+1)th frame at the first frequency point.

[0103] In one implementation, pilot blind estimation of OFDM signals is achieved by thresholding the correlation values ​​of N frequency points, including:

[0104] The correlation values ​​of N frequency points are normalized to obtain the normalized correlation values ​​of N frequency points;

[0105] Frequency points where the normalized correlation value exceeds a preset threshold are identified as pilot locations to achieve blind estimation of OFDM signal pilots.

[0106] In this embodiment of the invention, normalizing the correlation values ​​of N frequency points can standardize the correlation values ​​relative to the number of OFDM symbols and frames, thereby eliminating the influence caused by the difference in the number of symbols and frames.

[0107] Through normalization, the correlation value at each frequency point is standardized, ensuring that they can be compared on the same scale. This processing step helps to more accurately assess the similarity and intensity of signals at different frequency points.

[0108] See Figure 4 , Figure 4 This is a schematic diagram illustrating threshold judgment of normalized correlation values ​​for N frequency points, provided by an embodiment of the present invention. The horizontal axis represents the frequency points, and the vertical axis represents the correlation amplitude. The normalized correlation value ranges from 0 to 1. The normalized correlation value can represent the similarity of frequency domain data for N frequency points; the larger the correlation value, the greater the similarity of the frequency points. Therefore, by setting a reasonable detection threshold, i.e., a preset threshold range of 0 to 1, threshold detection can be performed on the normalized correlation values ​​of N frequency points.

[0109] Frequency points where the normalized correlation value exceeds a preset threshold are identified as pilot locations to achieve blind estimation of OFDM signal pilots.

[0110] In one implementation, the OFDM signal pilot blind estimation method also includes:

[0111] Obtain the two-dimensional array Z corresponding to the frequency point of the pilot position; calculate the reciprocal V of the magnitude variance of the two-dimensional array Z in the frame dimension. m The inverse of the variance of the magnitude in the sign dimension, V t ;

[0112] According to V m and V t The pilot value corresponding to the pilot position is determined to be either a pseudo-random value or a fixed value.

[0113] In this embodiment of the invention, after obtaining the pilot position, based on the frequency point n corresponding to the pilot position, the two-dimensional array Z corresponding to the frequency point n is obtained as Zn. Pilot values ​​of different frames and different OFDM symbols but the same frequency point n are obtained, and the reciprocal V of the magnitude variance of Zn in the frame dimension is calculated. m The inverse of the variance of the magnitude in the sign dimension, V t Therefore, based on V m and V t The magnitude relationship determines whether the pilot value corresponding to the pilot position is a pseudo-random value or a fixed value.

[0114] V m The calculation method is as follows:

[0115]

[0116] in, This represents the frequency domain data in the u-th OFDM symbol of the M-th frame at the n-th frequency point.

[0117] V t The calculation method is as follows:

[0118]

[0119] in, This represents the frequency domain data in the U-th OFDM symbol of the m-th frame at the n-th frequency point.

[0120] In one implementation, according to V m and V t Determining whether the pilot value corresponding to the pilot position is a pseudo-random value or a fixed value includes:

[0121] When V t Greater than V m At that time, the pilot value corresponding to the pilot position is a fixed value;

[0122] When V m Greater than V t When determining the pilot position, the pilot value is a pseudo-random value.

[0123] In this embodiment of the invention, when V t Greater than V m At this time, the pilot value remains unchanged between each OFDM symbol, that is, the first pilot value of the first OFDM symbol is the same as the first pilot value of the second OFDM symbol. Therefore, the pilot value corresponding to the pilot position is a fixed value.

[0124] When V m Greater than V tAt that time, the pilot value is pseudo-random between each OFDM symbol, but the pilot value remains unchanged between frames. That is, the first pilot value of the first OFDM in the same frame is different from the first pilot value of the second OFDM, but the pilot value of the first OFDM symbol in the first frame is the same as the pilot value of the first OFDM symbol in the second frame. Therefore, the pilot value corresponding to the pilot position is a pseudo-random value.

[0125] The OFDM signal pilot blind estimation method provided in this embodiment of the invention can be applied to a variety of scenarios, such as radio reconnaissance scenarios.

[0126] Based on the OFDM signal pilot blind estimation method for electronic reconnaissance provided in this embodiment of the invention, simulation experiments were conducted using MATLAB 2023a software. The channel used in the simulation experiment was an additive white Gaussian noise channel. Other simulation parameters are detailed in Table 1 below:

[0127] Table 1 Simulation Parameters

[0128] parameter numerical values unit Subcarrier gap 234375 Hz Signal-to-noise ratio 0:10 dB Frequency offset 0 Hz Frames 10 Symbolic Number 60 pilot number 20 Data modulation method QPSK / 16QAM / 64QAM / 256QAM Pilot modulation method BPSK / QPSK Pilot Insertion Method comb-like FFT points 1024 Cyclic prefix length 0.133 us

[0129] The simulation results obtained based on the above simulation parameters for the OFDM signal pilot blind estimation method for electronic reconnaissance provided in this embodiment of the invention can be found in [reference]. Figure 5 , Figure 6 and Figure 7 The details are as follows:

[0130] Figure 5 This is a schematic diagram illustrating the correct probability of pilot estimation under different data modulation and pilot modulation methods. Figure 5 The CCP used OFDM signals modulated by five sets of data modulation and pilot modulation methods: QPSK (Quadrature Phase Shift Keying) + BPSK (Binary Phase Shift Keying), QPSK+QPSK, 16QAM (Quadrature Amplitude Modulation) + BPSK, 16QAM+QPSK, 64QAM+BPSK, 64QAM+QPSK, 256QAM+BPSK, and 256QAM++QPSK. Using the OFDM signal pilot blind estimation method for electronic reconnaissance provided in this embodiment of the invention, simulations of the pilot position estimation accuracy performance were performed on OFDM signals obtained by the five different data modulation and pilot modulation methods. It can be seen that under different modulation methods, no frequency offset, and low signal-to-noise ratio (SNR = 0dB), the accuracy estimation probability of this method for pilot position estimation can reach 95%, and it can achieve 100% accuracy at 3dB.

[0131] Figure 6 This is a schematic diagram of the frequency offset resistance range. Figure 6 Taking the OFDM signal data modulation scheme and pilot modulation scheme as 16QAM+QPSK as an example, under four signal-to-noise ratios (SNR) of 4dB, 6dB, 8dB, and 10dB, the OFDM signal pilot blind estimation method provided in this embodiment of the invention has a bias resistance of ±0.3. Even at a high SNR of 10dB, with a frequency offset of ±0.4, a correct estimation probability of over 90% can be achieved.

[0132] Figure 7 This is a schematic diagram illustrating the probability of correct pilot position estimation under different frame numbers and signal-to-noise ratios. Figure 7 The correct pilot position estimation probabilities are presented for frame numbers ranging from 2 to 16 and signal-to-noise ratios (SNR) of 6 dB, 8 dB, 10 dB, 12 dB, and 15 dB. At a high SNR of 15 dB, the correct pilot position estimation probability reaches 100% with only 3 frames (10 OFDM symbols per frame), resulting in a total estimation of 30 OFDM symbols. At a low SNR of 6, a correct estimation probability of 90% is achieved with at least 10 received frames.

[0133] Based on the same inventive concept, embodiments of the present invention also provide an OFDM signal pilot blind estimation device applied in electronic reconnaissance, see [link to previous document]. Figure 8 , Figure 8 This is a schematic diagram of a blind OFDM signal pilot estimation device for electronic reconnaissance provided in an embodiment of the present invention. The blind OFDM signal pilot estimation device includes:

[0134] FFT module 801 is used to perform FFT on the OFDM signal after blind time-frequency synchronization of M frames to obtain OFDM frequency domain data of M frames; wherein each OFDM frequency domain data includes U OFDM symbols;

[0135] The frequency domain data reassembly module 802 is used to reassemble frequency domain data from different frames, different OFDM symbols, and the same frequency point to obtain N two-dimensional arrays Z; wherein, the two-dimensional array Z includes M vectors Y; each vector Y includes U frequency domain data;

[0136] The conjugate multiplication operation module 803 is used to select one vector Y from M vectors Y for each two-dimensional array Z and perform conjugate multiplication with the M-1 unselected vectors Y respectively to obtain M-1 vectors C;

[0137] The one-dimensional vector acquisition module 804 is used to accumulate M-1 vectors C for each frequency point, and calculate the modulus of the accumulated terms to obtain the one-dimensional vector corresponding to that frequency point;

[0138] The correlation value acquisition module 805 is used to accumulate the one-dimensional vector corresponding to each frequency point to obtain the correlation value of that frequency point;

[0139] The threshold judgment module 806 is used to realize the pilot blind estimation of OFDM signal by performing threshold judgment on the correlation values ​​of N frequency points.

[0140] In this embodiment of the invention, by accumulating M-1 vectors C for each frequency point and then calculating the modulus of the accumulated terms, the impact of frequency offset on pilot blind estimation can be effectively reduced. Even with a large residual frequency offset, high-accuracy pilot blind estimation can still be performed, and the correctness of the pilot blind estimation is unaffected by the data of the OFDM signal at the transmitting end and the pilot modulation method.

[0141] Furthermore, since the frequency domain data of different frames, different OFDM symbols, and the same frequency point are recombined, N two-dimensional arrays Z are obtained by making full use of the characteristics of OFDM signals in the frequency and time domains. Therefore, even when the amount of OFDM signal data received is low, pilot blind estimation of OFDM signals can still be performed.

[0142] Optionally, there is a one-to-one correspondence between the M vectors Y and the OFDM frequency domain data of the M frames;

[0143] The conjugate multiplication operation module is specifically used to select the vector Y corresponding to the OFDM frequency domain data of the first frame from M vectors Y for each two-dimensional array Z as a local sequence; and to perform conjugate multiplication operations on the local sequence and the M-1 unselected vectors Y respectively to obtain M-1 vectors C.

[0144] Optionally, the threshold judgment module is specifically used to normalize the correlation values ​​of N frequency points to obtain normalized correlation values ​​of N frequency points; and to determine the frequency points whose normalized correlation values ​​exceed a preset threshold as pilot positions, so as to realize pilot blind estimation of OFDM signals.

[0145] Optionally, the OFDM signal pilot blind estimation device further includes a pilot value determination module;

[0146] The pilot value determination module is used to obtain a two-dimensional array Z corresponding to the frequency point corresponding to the pilot position; and to calculate the reciprocal V of the magnitude variance of the two-dimensional array Z in the frame dimension. m The inverse of the variance of the magnitude in the sign dimension, V t According to V m and V tThe pilot value corresponding to the pilot position is determined to be either a pseudo-random value or a fixed value.

[0147] Optionally, in the pilot value determination module, based on V m and V t Determining whether the pilot value corresponding to the pilot position is a pseudo-random value or a fixed value includes:

[0148] When V t Greater than V m At that time, the pilot value corresponding to the pilot position is determined to be a fixed value;

[0149] When V m Greater than V t When the pilot value corresponding to the pilot position is determined to be a pseudo-random value.

[0150] This invention also provides an electronic device, such as... Figure 9 As shown, it includes a processor 901, a communication interface 902, a memory 903, and a communication bus 904, wherein the processor 901, the communication interface 902, and the memory 903 communicate with each other through the communication bus 904.

[0151] Memory 903 is used to store computer programs;

[0152] When the processor 901 executes the program stored in the memory 903, it implements the steps of the method described in any of the OFDM signal pilot blind estimation methods applied in electronic reconnaissance.

[0153] The communication bus mentioned in the above electronic devices can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of representation, only one thick line is used in the diagram, but this does not indicate that there is only one bus or one type of bus.

[0154] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0155] The memory may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0156] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0157] The present invention also provides a computer-readable storage medium. A computer program is stored in the computer-readable storage medium, and when executed by a processor, the computer program implements the steps of any of the above-described OFDM signal pilot blind estimation methods applied in electronic reconnaissance.

[0158] Optionally, the computer-readable storage medium may be non-volatile memory (NVM), such as at least one disk storage device.

[0159] Optionally, the computer-readable storage device may also be at least one storage device located remotely from the aforementioned processor.

[0160] In another embodiment of the present invention, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to perform the steps of any of the OFDM signal pilot blind estimation methods applied in electronic reconnaissance described above.

[0161] It should be noted that the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention.

[0162] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0163] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings and the disclosure in carrying out the claimed invention. In the description of the invention, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0164] The method provided in this invention can be applied to electronic devices. Specifically, the electronic device can be a desktop computer, a portable computer, a smart mobile terminal, a server, etc. No limitation is made herein; any electronic device that can implement this invention falls within the protection scope of this invention.

[0165] For the embodiments of the device / electronic device / storage medium, since they are basically similar to the method embodiments, the description is relatively simple, and relevant parts can be referred to in the description of the method embodiments.

[0166] It should be noted that the device, electronic device and storage medium in the embodiments of the present invention are respectively the device, electronic device and storage medium for applying the above-mentioned OFDM signal pilot blind estimation method in electronic reconnaissance. Therefore, all embodiments of the above-mentioned OFDM signal pilot blind estimation method in electronic reconnaissance are applicable to the device, electronic device and storage medium, and can achieve the same or similar beneficial effects.

[0167] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A pilot blind estimation method of OFDM signals applied in electronic reconnaissance, characterized in that, The method comprises the steps that: To M The OFDM signal after frame blind time-frequency synchronization is subjected to FFT to obtain M OFDM frequency domain data of the frame; wherein each OFDM frequency domain data includes U OFDM symbols; The frequency domain data of different frames, different OFDM symbols and same frequency points are recombined to obtain N a two-dimensional array Z ; wherein the two-dimensional array Z includes M vectors Y ; each vector Y includes U frequency domain data; For each two-dimensional array Z , from M , one vector Y is selected Y from the M -1 vectors Y , respectively, are conjugate multiplied to obtain M -1 vectors C ; For each frequency point, the following is done M -1 vector C is accumulated, and the modulus of the accumulated term is taken to obtain a one-dimensional vector corresponding to the frequency point; For each frequency point, a one-dimensional vector corresponding to the frequency point is accumulated to obtain a correlation value of the frequency point; By threshold judging the correlation value of the N frequency points, the OFDM signal pilot blind estimation is realized. The frequency domain data of different frames, different OFDM symbols and same frequency points are reorganized to obtain N a two-dimensional array Z , comprising: For each frame, a one-dimensional vector containing U elements is formed; where, U represents the number of OFDM symbols; the number of frequency domain data of the same frequency point in each frame is equal to the number of OFDM symbols; For each frequency point, a vector of size is obtained from the one-dimensional vector formed by each frame. M * U Two-dimensional array Z ;in, M Indicates the number of frames; A two-dimensional array is obtained through each frequency point Z , and a two-dimensional array N is obtained Z ; wherein N represents the number of frequency points.

2. The pilot blind estimation method of OFDM signals according to claim 1, characterized in that, M vector Y and M OFDM frequency domain data of a frame For each two-dimensional array Z , from M vectors Y , a vector Y is selected M -1 vector Y is respectively conjugate multiplied, and M -1 vector C is obtained, comprising: For each two-dimensional array Z , from M vectors Y , the vector corresponding to the OFDM frequency domain data of the first frame is selected Y as the local sequence; said local sequence with the non-selected M -1 vector Y respectively, by a conjugate multiplication operation M -1 vector C .

3. The pilot blind estimation method of OFDM signals according to claim 1, characterized in that, By threshold judging the correlation value of the N frequency points, the OFDM signal pilot blind estimation is realized, including: right N The correlation values ​​at each frequency point are normalized to obtain N Normalized correlation values ​​for each frequency point; The frequency point with a normalized correlation value exceeding a preset threshold is determined as a pilot position to realize blind estimation of the OFDM signal pilot.

4. The pilot blind estimation method of OFDM signals according to claim 3, characterized in that, The method for blind estimation of the OFDM signal pilot further comprises the steps that: According to the frequency point corresponding to the pilot position, a two-dimensional array corresponding to the frequency point is obtained Z ; calculate the two-dimensional array Z The reciprocal of the modulus value variance in the frame dimension And the reciprocal of the modulus value variance in the symbol dimension ; According to and determining whether the pilot value corresponding to the pilot position is a pseudo-random value or a fixed value.

5. The pilot blind estimation method of OFDM signals according to claim 4, characterized in that, According to and determining whether the pilot value corresponding to the pilot position is a pseudo-random value or a fixed value comprises: When greater than , it is determined that the pilot value corresponding to the pilot position is a fixed value. When greater than the pilot value corresponding to the pilot position is determined to be a pseudo-random value.

6. An OFDM signal pilot blind estimation device applied in electronic reconnaissance, characterized in that, The method comprises the steps that: The FFT module is used for... M The OFDM signal after frame-blind time-frequency synchronization is subjected to FFT to obtain... M OFDM frequency domain data of the frame; wherein each OFDM frequency domain data includes U One OFDM symbol; The frequency domain data reorganization module is configured to reorganize frequency domain data of different frames, different OFDM symbols and same frequency points to obtain N a two-dimensional array Z ; wherein the two-dimensional array Z includes M a plurality of vectors Y ; each vector Y includes U frequency domain data; A conjugate multiplication operation module is configured to perform a conjugate multiplication operation on each of the two-dimensional arrays Z , from M , and Y , and Y , and M , and Y , respectively, to obtain M , and C . A one-dimensional vector generation module is used to, for each frequency point, [determine / generate] its... M -1 vectors C Accumulate the terms and calculate the modulus of the accumulated terms to obtain the one-dimensional vector corresponding to the frequency point. A correlation value obtaining module is configured to accumulate, for each frequency point, a one-dimensional vector corresponding to the frequency point to obtain a correlation value of the frequency point; The threshold determination module is used to determine the threshold value by... N Threshold judgment is performed on the correlation values ​​of each frequency point to achieve blind estimation of OFDM signal pilots; The frequency domain data reconstruction module is specifically used to: for each frame, form a data structure containing... U A one-dimensional vector with n elements; where... U This represents the number of OFDM symbols; the number of frequency domain data points at the same frequency point in each frame is equal to the number of OFDM symbols; for each frequency point, a one-dimensional vector of size is obtained from the corresponding one-dimensional vector formed by each frame. M * U Two-dimensional array Z ;in, M Represents the number of frames; a two-dimensional array obtained from each frequency point. Z ,get N A two-dimensional array Z ;in, N Indicates the number of frequency points.

7. The OFDM signal pilot blind estimation device of claim 6, wherein, M a vector Y and M OFDM frequency domain data of a frame one-to-one correspondence; The conjugate multiplication operation module is specifically used for each two-dimensional array. Z ,from M vectors Y The vector corresponding to the OFDM frequency domain data of the first frame is selected. Y As a local sequence; the local sequence is then compared with the unselected sequence. M -1 vectors Y Perform conjugate multiplication operations separately to obtain M -1 vectors C .

8. The OFDM signal pilot blind estimation apparatus of claim 6, wherein, The threshold determination module is specifically used for determining the threshold value. N The correlation values ​​at each frequency point are normalized to obtain N The normalized correlation value of each frequency point; the frequency point whose normalized correlation value exceeds the preset threshold is determined as the pilot position, so as to realize the pilot blind estimation of OFDM signal.

9. An electronic device, comprising: The device comprises a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory complete communication with each other through the communication bus; The memory is configured to store a computer program; The processor is configured to execute the program stored in the memory to realize the method for blind estimation of the OFDM signal pilot according to any one of claims 1-5.

10. A computer-readable storage medium, characterized in that, The computer program stored in the computer readable storage medium is executed by the processor to realize the method for blind estimation of the OFDM signal pilot according to any one of claims 1-5.

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