Multi-antenna frequency domain enhanced wireless communication secure transmission system and method

Abstract

The invention discloses a multi-antenna frequency domain enhanced wireless communication secure transmission system and method, and relates to the technical field of wireless communication, and the system comprises a security component, a transmitting end and a receiving end. The security component is used for generating keys K1 and K2. The transmitting end assembly comprises a baseband module used for scrambling, channel coding, constellation diagram scrambling based on K1 and serial-to-parallel conversion; the OFDM module is used for inserting a preamble training signal, constructing an OFDM matrix, inserting a pilot signal, performing inverse fast Fourier transform, adding a cyclic prefix and generating a time domain transmitting signal; and the space-frequency block coding module is used for coding between the OFDM matrix subcarrier and the antenna based on K2 activation. The receiving end assembly comprises a synchronization module used for realizing frame synchronization, channel estimation and equalization; and the receiving module is used for OFDM demodulation, space-frequency decoding, de-mapping and antenna matching. By applying the invention, the problems that the modulation mode is easy to crack, the antenna configuration is fixed, the channel characteristics are not fully utilized and the like in the existing secure transmission scheme can be solved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technologies, and more particularly to a wireless communication secure transmission system and method with enhanced multi-antenna frequency domain. Background Art

[0002] In the field of wireless communication, with the development of technologies, the data transmission rate and network coverage have been significantly improved. However, this has also brought challenges to secure transmission. Especially in MIMO (Multiple-Input Multiple-Output) systems, although the use of multiple antennas improves the channel capacity and signal quality, the system is more vulnerable to eavesdropping and attack threats. To address this challenge, researchers have proposed various secure transmission schemes, including superposition coding design hierarchical broadcast approximation, artificial noise-assisted transmission technologies, and physical layer-based security technologies, etc.

[0003] Orthogonal Frequency Division Multiplexing (OFDM) technology, as a modulation technology, can effectively resist frequency-selective fading. By dividing the channel into a series of flat sub-channels, it improves the spectrum utilization rate and anti-interference ability. Multiple-Input Multiple-Output (MIMO) technology fully exploits spatial resources and uses multiple antennas to achieve multiple-input multiple-output. Without increasing the spectrum resources and antenna transmission power, it can double the channel capacity. The MIMO-OFDM system combining MIMO technology not only improves the spectrum efficiency but also enhances the anti-interference performance of the system.

[0004] Space-Frequency Block Codes (SFBC) are used to send multiple copies of the data stream on multiple antennas and utilize various received data versions to improve the reliability of data transmission. As a coding technology applied in MIMO-OFDM systems, it effectively utilizes spatial and frequency diversity gains by coding between different transmit antennas and OFDM sub-carriers.

[0005] However, an attacker can complete eavesdropping and deciphering through a large-scale MIMO antenna array during the signal transmission process in the wireless channel. Existing secure transmission schemes have problems such as the modulation method being easily cracked, the antenna configuration being fixed, and the channel characteristics not being fully utilized. Summary of the Invention

[0006] The object of the present invention is to provide a multi - antenna frequency - domain enhanced wireless communication secure transmission system and method. Through constellation scrambling and antenna activation controlled by dynamic keys, combined with space - frequency diversity technology, the present invention improves security, anti - fading ability and spectral efficiency simultaneously without increasing spectral resources, filling the deficiency in the physical - layer security design of the prior art.

[0007] To achieve the above object, the present invention adopts the following technical solutions.

[0008] A multi - antenna frequency - domain enhanced wireless communication secure transmission system includes a security component, a transmitting - end component and a receiving - end component.

[0009] The security component is used to generate dynamic key sets K1 and K2 through a wireless - channel key, where K1 controls constellation scrambling and K2 controls the activation mode of transmitting antennas.

[0010] The transmitting - end component includes: A base - band transmitting - signal processing module, which is used to scramble, channel - encode, symbol - map and perform serial - to - parallel conversion on source data, where the symbol - mapping dynamically scrambles the constellation diagram based on K1; An OFDM transmitting - signal processing module, which is used to construct an OFDM transmitting - signal matrix, insert a preamble training signal before the matrix, perform an inverse fast Fourier transform, and add a cyclic prefix to generate a time - domain transmitting signal, where pilot signals are inserted when constructing the OFDM transmitting - signal matrix; A space - frequency block coding module, which is used to perform coding among the sub - carriers of the OFDM transmitting - signal matrix and the transmitting antennas activated based on K2.

[0011] The receiving - end component includes: A synchronization and channel - estimation module, which is used to achieve frame synchronization according to the preamble training signal and complete channel estimation and equalization based on the pilot signals. A receiving - end signal - processing module, which is used for OFDM demodulation, space - frequency decoding, symbol - demapping based on K1 and K2, and antenna - mode matching to recover the original bit stream. Further, in symbol - mapping, the constellation mapping is scrambled by using the angle randomly generated by K1 to realize the scrambling of the constellation diagram.

[0012] Further, when activating antennas, according to the binary sequence generated by K2, the transmitting - antenna combination is dynamically selected, and the unactivated antennas are turned off during the transmitting period.

[0013] Further, the dynamic key sets K1 and K2 are dynamically generated through channel - response negotiation based on the space - time uniqueness feature of the wireless channels between legitimate transceivers.

[0014] Furthermore, space-frequency block coding distributes symbol pairs among adjacent subcarriers and antennas, while leveraging spatial diversity and frequency diversity gains.

[0015] A secure transmission method for multi-antenna frequency-domain enhanced wireless communication, comprising the following steps: S1. Perform baseband processing on the source data at the transmitter, including scrambling, channel coding, constellation scrambling symbol mapping based on key K1, and serial-to-parallel conversion; S2. Construct an OFDM transmission signal matrix and insert pilot signals, and insert a preamble training signal in front of the matrix; S3. Perform space-frequency block coding among the respective subcarriers of the OFDM transmission signal matrix and the transmit antennas activated based on key K2; S4. Perform inverse fast Fourier transform on the signal after space-frequency block coding and add a cyclic prefix to generate a time-domain transmission signal, and transmit it through the activated transmit antennas; S5. The receiving antenna receives the signal, and performs frame synchronization, channel estimation, and equalization at the receiver, extracts the pilot signal to recover the channel state information; S6. Use K1 to inversely demap the scrambled constellation diagram, and match the activated antenna pattern through K2 to complete OFDM demodulation and space-frequency decoding; S7. Perform despreading, deinterleaving, and channel decoding on the signal to recover the original data.

[0016] Furthermore, in step S1, a random phase angle is generated through key K1, and the symbols in the constellation diagram are phase-rotated to form a dynamically scrambled constellation mapping table. In step S6, the legitimate receiver reversely rotates the same angle based on the same K1 to recover the original constellation diagram.

[0017] Furthermore, in step S2, the preamble training signal is generated separately and added to the head of the transmission signal matrix for signal synchronization and frequency offset estimation. The pilot signals are uniformly inserted into the OFDM transmission signal matrix at fixed intervals, and the insertion density matches the maximum Doppler frequency shift of the channel to ensure real-time tracking ability under high-dynamic channels.

[0018] Furthermore, in step S3, space-frequency block coding enhances the anti-interference ability through the combined gains of spatial diversity and frequency diversity.

[0019] Furthermore, in step S6, the receiving end generates a binary sequence according to K2, filters out the received signal streams corresponding to the activated transmit antennas at the transmitting end, and performs space-frequency decoding.

[0020] After adopting the above technical solution, the present invention has the following beneficial effects: 1. The present invention encrypts through dynamic constellation scrambling and antenna activation mode, making it impossible for attackers to identify the modulation method and effective signal flow, significantly increasing the eavesdropping difficulty and strengthening communication security. 2. The present invention realizes effective resistance to multipath fading and frequency selective interference by integrating space-frequency diversity technology, ensures accurate data transmission under complex channels, and improves the reliability of wireless transmission. 3. By combining multiple-input multiple-output (MIMO) and orthogonal frequency division multiplexing (OFDM) technologies, the present invention doubles the channel capacity and spectrum utilization rate without increasing bandwidth and power, improving the spectrum transmission efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the schematic diagram of the SFBC-OFDM-MIMO secure transmission system in the present invention.

[0022] Figure 2 is the schematic diagram of the frame structure in the present invention.

[0023] Figure 3 is the schematic diagram of the security design process of the SFBC-OFDM-MIMO system in the present invention.

[0024] Figure 4 is the constellation diagram obtained by the legitimate receiver.

[0025] Figure 5 is the constellation diagram obtained by the eavesdropper.

[0026] Figure 6 is the comparison diagram of the bit error rate between the legitimate receiver and the attacker. DETAILED DESCRIPTION OF THE INVENTION

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the features and performances of a multi-antenna frequency domain enhanced wireless communication secure transmission system and method in the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0028] Please refer to the attached Figures 1 to 3 , a multi-antenna frequency domain enhanced wireless communication secure transmission system, including a security component, a transmitter component and a receiver component.

[0029] The security component is used to generate dynamic key sets K1 and K2 through a wireless channel key. The dynamic key sets K1 and K2 are dynamically generated through channel response negotiation based on the spatio-temporal uniqueness characteristics of the wireless channels of the legitimate transceiver parties. Among them, K1 controls constellation scrambling, and K2 controls the activation mode of the transmitting antennas. Specifically, when the antennas are activated, according to the binary sequence generated by K2, the transmitting antenna combination is dynamically selected, and the unactivated antennas are turned off during the transmission period.

[0030] The transmitting end component includes: A baseband transmitting signal processing module, which is used to scramble, channel code, symbol map, and serial-to-parallel conversion of the source data, where the symbol map dynamically scrambles the constellation diagram based on K1. Specifically, in the symbol map, the constellation map is scrambled by using the angle randomly generated by K1 to perform constellation mapping, realizing the scrambling of the constellation diagram.

[0031] An OFDM transmitting signal processing module, which is used to insert a preamble training signal into the data, construct an OFDM transmitting signal matrix, perform an inverse fast Fourier transform, and add a cyclic prefix to generate a time-domain transmitting signal, where a pilot signal is inserted when constructing the OFDM transmitting signal matrix.

[0032] A space-frequency block coding module, which is used to perform coding between each subcarrier of the OFDM transmitting signal matrix and the transmitting antennas activated based on K2. Specifically, the space-frequency block coding distributes symbol pairs among adjacent subcarriers and antennas, while utilizing the space diversity and frequency diversity gains.

[0033] The receiving end component includes: A synchronization and channel estimation module, which is used to achieve frame synchronization according to the preamble training signal, and complete channel estimation and equalization based on the pilot signal.

[0034] A receiving end signal processing module, which is used for OFDM demodulation, space-frequency decoding, symbol demapping based on K1 and K2, and antenna pattern matching to recover the original bit stream.

[0035] A wireless communication secure transmission method with multi-antenna frequency domain enhancement includes the following steps: S1. Perform baseband processing on the source data at the transmitting end, including scrambling, channel coding, constellation scrambling symbol mapping based on the key K1, and serial-to-parallel conversion. Specifically, a random phase angle is generated by the key K1 to perform phase rotation on the symbols in the constellation diagram, forming a dynamically scrambled constellation mapping table.

[0036] S2. Insert a preamble training signal into the data, construct an OFDM transmitting signal matrix, and insert a pilot signal when constructing the OFDM transmitting signal matrix. Specifically, the preamble training signal is generated separately and added to the head of the transmitting signal matrix for signal synchronization and frequency offset estimation. The pilot signal is uniformly inserted into the OFDM transmitting signal matrix at a fixed interval, and the insertion density matches the maximum Doppler frequency shift of the channel to ensure the real-time tracking ability under a high-dynamic channel.

[0037] S3. Perform space-frequency block coding between each subcarrier of the OFDM transmitting signal matrix and the transmitting antennas activated based on the key K2. The space-frequency block coding improves the anti-interference ability through the combined gain of space diversity and frequency diversity.

[0038] S4. Perform an inverse fast Fourier transform on the signal after space-frequency block coding and add a cyclic prefix to generate a time-domain transmission signal, which is then transmitted through the activated transmit antennas.

[0039] S5. The receiving antennas receive the signal, and frame synchronization, channel estimation, and equalization are performed at the receiving end to extract the pilot signal and recover the channel state information.

[0040] S6. The legitimate receiving end uses K1 to inversely demap the scrambled constellation diagram and rotates the same angle based on the same K1 to recover the original constellation diagram. The receiving end matches the activated antenna pattern through K2, and according to the binary sequence generated by K2, filters out the received signal stream corresponding to the activated transmit antennas at the transmit end, performs space-frequency decoding, and completes OFDM demodulation and space-frequency decoding.

[0041] S7. Despread, deinterleave, and channel decode the signal to recover the original data.

[0042] In specific implementation, the present invention aims to solve the key technical problems in wireless communication systems - how to ensure the security and reliability of data transmission in the presence of potential eavesdroppers. In modern communication technologies, multiple-input multiple-output (MIMO) and orthogonal frequency-division multiplexing (OFDM) technologies have been widely used to improve communication efficiency and signal quality. However, while these technologies enhance the system performance, they also make the system more vulnerable to eavesdropping and attack threats. An attacker can use MIMO technology to capture and analyze signals through a large-scale antenna array, thereby attempting to decipher the transmitted data.

[0043] To address this challenge, the present invention proposes a secure transmission system and method for wireless communication with enhanced multi-antenna frequency domain. By combining SFBC, OFDM, and MIMO technologies, as well as innovative security designs, the system achieves a multiple-fold increase in channel capacity and spectral efficiency without increasing spectral resources and antenna transmit power, while suppressing the adverse effects brought by multipath effects and frequency-selective fading.

[0044] The technical solution of the present invention includes key parts such as baseband transmission signal processing, OFDM transmission signal processing, SFBC technology, synchronization algorithm, channel estimation and equalization algorithm, OFDM reception signal processing, and baseband reception signal processing. In particular, the security design part generates a wireless channel key set K1 and K2 through wireless channel key extraction, where K1 controls symbol mapping, i.e., the constellation scrambling of the modulation method, and K2 controls antenna activation, thereby realizing the scrambling of the constellation diagram and the encryption of the antenna transmission mapping mode, effectively preventing attackers from deciphering the modulation method and eavesdropping on data.

[0045] The block diagram of the SFBC-OFDM-MIMO system is as Figure 1As shown in the figure, the system mainly consists of a baseband transmission signal processing module, an OFDM transmission signal processing module, a space-frequency block coding module, a synchronization and channel estimation module, an OFDM reception signal processing module, a space-frequency block decoding module, a baseband reception signal processing module, etc.

[0046] The frame structure matrix form of the SFBC-OFDM-MIMO system is as Figure 2 shown, and it mainly consists of three parts, namely: a preamble training part, a pilot part, and a data part. The preamble training part is mainly used for signal synchronization and rough estimation of frequency offset. The preamble training signal is generated separately and finally added to the head of the transmission signal matrix. The pilot part is mainly used for channel estimation, signal detection, and precise estimation of frequency offset. The separately generated pilot signals are evenly inserted into the transmission signal matrix, which is suitable for fast-fading channels and can effectively track the dynamic changes of the channel. The data part is mainly used for transmitting service data, which includes data such as user information, CRC check code, and rate identification code, and is generated by the baseband signal.

[0047] The baseband transmission signal processing module is used for source scrambling, channel coding and interleaving, spreading, symbol mapping, and serial-to-parallel conversion, where the symbol mapping is modulation methods such as BPSK, QPSK, 8PSK, 16QAM, etc.

[0048] The OFDM transmission signal processing module is used to construct an OFDM transmission signal matrix and insert pilot signals, insert preamble training signals into the data, perform inverse fast Fourier transform, and add a cyclic prefix to generate a time-domain transmission signal. The data signal forms an OFDM transmission signal matrix after baseband processing. The pilot signals are evenly inserted into the data signal matrix, and the generated preamble training sequence is placed before the transmission signal matrix.

[0049] In actual engineering, when constructing the OFDM transmit signal matrix, synchronization and channel estimation need to be performed. Known PN codes (i.e., pilot signals) are inserted into the OFDM signal matrix. The PN code symbols are pre-generated and are known to both the transmitter and the receiver. Since the OFDM transmit signal matrix is a frequency-domain signal matrix, it needs to be transformed into a time-domain signal matrix for transmission. Therefore, the Inverse Fast Fourier Transform (IFFT) is used for calculation to obtain the time-domain transmit signal matrix. To eliminate the Inter-Symbol Interference (ISI) caused by channel and other interferences, a Cyclic Prefix (CP) is added to the OFDM signal matrix. After serial-to-parallel conversion, the CP signal is evenly embedded into each symbol time. Because the transmission paths are different, when the receiver receives the serial data, if there is interference between adjacent symbols, it only affects the amplitude change of the CP signal, and the amplitude of the required signal is not interfered by other signals, thus eliminating the influence of ISI interference.

[0050] The space-frequency block coding module is used to perform coding between each subcarrier of the OFDM transmit signal matrix and the transmit antennas activated based on K2.

[0051] Space-Frequency Block Coding (SFBC) is a coding method suitable for frequency-selective channels. This coding introduces coding technology between each subcarrier of OFDM and the transmit antennas, thereby obtaining spatial diversity and frequency diversity simultaneously. SFBC is introduced in the MIMO-OFDM system because the OFDM system itself introduces the frequency domain, and the OFDM system modulates the signal onto multiple different subcarrier frequencies for parallel transmission.

[0052] Specifically, assume the number of transmit antennas is M T , and the number of receive antennas is M R , and the total bandwidth of the system is W Hz. Let x(m) be the signal after coding and mapping, which becomes the signal in the signal constellation set. Then, the signal with a period of T d is passed through a serial-to-parallel converter to form a symbol vector of length K: X(n) = [x(nk), x(nk + 1),..., x(nk + K - 1)] T , whose period is KT d .

[0053] X(n) can then be subjected to space-frequency coding to obtain M T parallel data streams: M T The parallel data streams are then assigned to different transmit antennas, respectively subjected to OFDM modulation, and then transmitted.

[0054] At the k-th subcarrier within the n-th OFDM symbol period, the M T ×1 dimensional signal vector to be transmitted is: where is the complex data symbol after OFDM modulation.

[0055] The synchronization and channel estimation module is used to achieve frame synchronization according to the preamble training signal after receiving the signal, and complete channel estimation and equalization based on the pilot signal.

[0056] The purpose of frame synchronization is to detect the frame header and confirm the starting position of the data frame. The received IQ baseband signal can be expressed as r(n). The correlator performs conjugate correlation accumulation on the input signal using the locally generated pilot signal. The local pilot symbol is a PN code, and the length of the pilot signal is determined according to different modulation methods. Assuming the length of the pilot signal symbol is N p , so the output of the correlator is:

[0057] The signal will be distorted during transmission in the channel. In order to recover the transmitted bit information, the influence of the channel needs to be estimated and compensated at the receiver. Usually, a semi-blind channel estimation method is used for channel estimation, that is, using the pilot (Pilot) symbols known to both the transmitter and the receiver for channel estimation, and different interpolation techniques can be used to estimate the channel response on the subcarriers between the pilots. Channel estimation is performed by pilot insertion, sacrificing fewer data signal positions. Only the pilot signals at the same positions required by both the transmitter and the receiver need to be determined. The receiver processes the pilot position signals to restore the signals at the data positions, that is, the pilot-assisted channel estimation method.

[0058] The receiving end signal processing module is used for OFDM demodulation, space-frequency decoding, symbol demapping based on K1 and K2, and antenna pattern matching to restore the original bit stream.

[0059] Since the synchronized serial signal is a time-domain signal, it needs to be converted to a frequency-domain signal for processing. Using the OFDM received signal processing module, first, a time-domain received signal matrix is obtained through serial-to-parallel conversion, and a CP removal operation is performed on it to eliminate the influence of ISI. Then, a frequency-domain received signal matrix is obtained through the forward fast Fourier transform (Fast Fourier Transform, FFT).

[0060] After the space-frequency block decoding module decodes the frequency-domain received signal matrix based on K2, the baseband received signal processing module performs demapping, despreading, channel decoding, and deinterleaving operations based on K1 to restore the original bit stream.

[0061] Specifically, after matched filtering at the receiving end, the signals on the receiving antennas are sampled, and the CP is deleted from each frame. Then the sampled values are input into the OFDM demodulator. The output of the k-th (k = 1,...K) OFDM demodulator for the j-th (j = 1, 2,...M R ) receiving antenna is: where H i,j (k,n) is the channel frequency response of the path from the i-th transmitting antenna to the j-th receiving antenna on the k-th OFDM subcarrier.

[0062] In the decoding of SFBC, first, the maximum likelihood decoding is used to estimate the transmitted space-frequency sequence. Assuming that the channel remains unchanged within an OFDM symbol and that the OFDM channels are uncorrelated with each other, and the receiver can obtain the ideal channel state information, the maximum likelihood decoding criterion can be expressed as: where the minimization is performed over all possible space-frequency codewords.

[0063] Secondly, the space-frequency decoder performs the inverse process of space-frequency coding to obtain Finally, ||·|| represents the Frobenius norm.

[0064] The security component is used to generate the dynamic key sets K1 and K2 through the wireless channel key, where K1 controls the constellation scrambling, and K2 controls the activation mode of the transmitting antennas.

[0065] The wireless channel key set K1 and K2 are generated through the wireless channel key extraction. K1 controls the symbol mapping, that is, the constellation scrambling of the modulation method, and K2 controls the antenna activation, as Figure 3 shown.

[0066] In the symbol mapping, taking the QPSK modulation method as an example, the angles [0, 2π] randomly generated by K1, such as θ1, θ2,...θ n scramble the constellation mapping to achieve the disruption of the constellation diagram and protect information such as the modulation method.

[0067] In the antenna combination, K2 is used to randomly select antennas for transmission, and the new antenna transmission mapping mode is combined. The activated antennas can be marked as 1, and the unactivated antennas are marked as 0. Therefore, the original two-dimensional symbol mapping mode becomes the encrypted three-dimensional modulation mapping. For the legitimate transmitter and the legitimate receiver, due to the space-time uniqueness of the wireless channel, they have the same keys K1 and K2. Therefore, the receiver can correctly demodulate and decode the information.

[0068] Through experiments and simulations, it is verified that the present invention can effectively protect the modulation mode of a legitimate communication system, making it difficult for an attacker to recover the original bits from the received symbols, while the legitimate receiver can correctly recover the original bits. As the signal-to-noise ratio increases, the receiving performance gets better and better, proving that the security of the system is guaranteed.

[0069] Specifically, the source data volume is 10^5 bits, the modulation mode is QPSK, the number of transmitting antennas and the number of receiving antennas are set to 64, and the wireless channel is a Rayleigh fading channel.

[0070] In the modulation mode, the rotation key for each constellation point is uniformly distributed in [0, 2π]. Since the eavesdropper is in a different position from the two legitimate communication parties, according to the spatio-temporal uniqueness of the wireless channel, the eavesdropper does not have the same key and it is very difficult to crack the modulation mode of the legitimate communication system. As Figure 4 and Figure 5 shown, the legitimate receiver can obtain the correct constellation diagram, while what the eavesdropper gets is a ring and no appropriate modulation information can be obtained from it.

[0071] Next, the reliability of the system is simulated. As Figure 6 can be seen, when the attacker uses the eavesdropping method, its bit error rate is always around 0.5 and it is completely impossible to recover the original bits from the received symbols. While the legitimate receiver can correctly recover the original bits, and as the signal-to-noise ratio increases, the receiving performance gets better and better. Therefore, it can be proved again that the security of the system is guaranteed.

[0072] In specific applications, different coding techniques can be considered, such as low-density parity-check (LDPC) codes or turbo codes, to replace the SFBC technique to adapt to different channel conditions and system requirements.

[0073] In terms of security design, more advanced encryption algorithms can be adopted, such as quantum key distribution (QKD), to further improve the security of the system.

[0074] The technical solution of the present invention is not only applicable to the field of wireless communication, but can also be extended to other data transmission scenarios that require high security and reliability, such as military communication, etc. This technology can also be applied to the secure communication between Internet of Things (IoT) devices to protect data from unauthorized access.

[0075] It should be noted that the parts not described in detail in this solution are all prior arts. The above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention all fall within the protection scope of the present invention.

Claims

1. A multi-antenna frequency domain enhanced wireless communication security transmission system, comprising a security component, a transmitting end component and a receiving end component, characterized in that: The security component is used to generate dynamic key sets K1 and K2 through the wireless channel key, where K1 controls the constellation scrambling and K2 controls the activation mode of the transmitting antenna; The transmitter components include: The baseband transmission signal processing module is used to perform scrambling, channel coding, symbol mapping and serial-to-parallel conversion on the source data. The symbol mapping dynamically scrambles the constellation diagram based on K1. The OFDM transmission signal processing module is used to construct the OFDM transmission signal matrix, insert the leading training signal in front of the matrix, perform inverse fast Fourier transform, add a cyclic prefix, and generate a time domain transmission signal. The pilot signal is inserted when constructing the OFDM transmission signal matrix. A space-frequency group coding module is used to encode between each subcarrier of the OFDM transmission signal matrix and the transmitting antenna based on K2 activation; The receiving end components include, The synchronization and channel estimation module is used to achieve frame synchronization based on the leading training signal and complete channel estimation and equalization based on the pilot signal. The receiving end signal processing module is used for OFDM demodulation, space-frequency decoding, symbol demapping based on K1 and K2, and antenna pattern matching to restore the original bit stream.

2. A wireless communication security transmission system with multi-antenna frequency domain enhancement as claimed in claim 1, characterized in that: In symbol mapping, the constellation diagram is disturbed by using the angle scrambled constellation mapping randomly generated by K1.

3. The multi-antenna frequency domain enhanced wireless communication security transmission system according to claim 1, characterized in that: When the antenna is activated, the transmitting antenna combination is dynamically selected according to the binary sequence generated by K2, and the inactivated antennas are turned off during the transmission cycle.

4. The multi-antenna frequency domain enhanced wireless communication security transmission system according to claim 1, characterized in that: The dynamic key sets K1 and K2 are dynamically generated through channel response negotiation based on the space-time uniqueness characteristics of the wireless channels between the legitimate sender and receiver.

5. The wireless communication security transmission system with multi-antenna frequency domain enhancement as claimed in claim 1, characterized in that: Space-frequency block coding allocates symbol pairs over adjacent subcarriers and antennas, exploiting both spatial diversity and frequency diversity gains.

6. A wireless communication security transmission method with multi-antenna frequency domain enhancement, characterized in that: The following steps are included: S1, baseband processing of the source data at the transmitting end, including scrambling, channel coding, constellation scrambling symbol mapping based on key K1, and serial-to-parallel conversion; S2, construct an OFDM transmission signal matrix and insert a pilot signal, and insert a leading training signal in front of the matrix; S3, performing space-frequency block coding between each subcarrier of the OFDM transmission signal matrix and the transmitting antenna activated based on the key K2; S4, performing inverse fast Fourier transform on the space-frequency block coded signal and adding a cyclic prefix to generate a time domain transmit signal, and sending it through the activated transmit antenna; S5, the receiving antenna receives the signal, and performs frame synchronization, channel estimation and equalization at the receiving end, extracts the pilot signal and restores the channel state information; S6, use K1 to reversely demap the scrambled constellation diagram, and activate the antenna mode through K2 matching to complete OFDM demodulation and space-frequency decoding; S7. Despread, deinterleave and channel decode the signal to restore the original data.

7. The method for secure transmission of wireless communication with multi-antenna frequency domain enhancement according to claim 6, characterized in that: In step S1, a random phase angle is generated by using the key K1, and the symbols in the constellation diagram are phase rotated to form a dynamically scrambled constellation mapping table. In step S6, the legitimate receiving end reversely rotates the same angle based on the same K1 to restore the original constellation diagram.

8. The method for secure transmission of wireless communication with multi-antenna frequency domain enhancement according to claim 6, characterized in that: In step S2, the pilot training signal is generated separately and added to the head of the transmit signal matrix for signal synchronization and frequency offset estimation. The pilot signal is evenly inserted into the OFDM transmit signal matrix at fixed intervals, and the insertion density matches the maximum Doppler frequency shift of the channel to ensure real-time tracking capability under high dynamic channels.

9. The method for secure transmission of wireless communication with multi-antenna frequency domain enhancement according to claim 6, characterized in that: In step S3, space-frequency block coding improves anti-interference capability through the joint gain of space diversity and frequency diversity.

10. The method for secure transmission of wireless communication with multi-antenna frequency domain enhancement according to claim 6, characterized in that: In step S6, the receiving end selects the received signal stream corresponding to the activated antenna of the transmitting end according to the binary sequence generated by K2, and performs space-frequency decoding.

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