Dynamic wireless key frequency hopping communication anti-interference system and method thereof

Abstract

The invention relates to a dynamic wireless key frequency hopping communication anti-interference system and a method thereof. The system comprises a transmitting end and a receiving end, the transmitting end comprises an information source scrambling module, a Turbo coding module, a spread spectrum module, a framing module, a frequency hopping pattern generation module and a forming filtering module; and the receiving end comprises a digital front-end processing module, a frequency hopping synchronization module, a signal synchronization module and a demodulation module. The frequency hopping pattern based on the chaotic system has high randomness and predictability, and tracking interference and eavesdropping are effectively resisted.

Description

Technical Field

[0001] The present invention relates to the field of anti-interference communication technology, and specifically relates to a dynamic wireless key hopping communication anti-interference system and its method. Background Art

[0002] With the rapid development of wireless communication technology, anti-interference technology has become increasingly important in the fields of military and civilian communication. Frequency hopping communication technology has been widely used due to its advantages in anti-interference and anti-interception. Frequency hopping technology reduces the probability of signal interception by changing the carrier frequency and enhances the anti-interference ability of the communication system. However, with the increase in the number of wireless devices and the intelligence of interference technology, the electromagnetic environment in which the frequency hopping network operates has become increasingly complex, and traditional anti-interference technologies can no longer meet the needs of modern communication.

[0003] In terms of the technical background, the existing frequency hopping communication systems mainly face two major challenges: one is how to maintain the stability and security of communication in a complex electromagnetic environment; the other is how to improve the anti-interference ability of the system while ensuring communication efficiency. To address these challenges, researchers have proposed a variety of intelligent anti-interference technologies, including a frequency hopping networking intelligent anti-interference decision algorithm based on multi-agent fuzzy deep reinforcement learning. This algorithm improves the convergence speed and optimal performance of the algorithm through centralized training and decentralized execution, showing good adaptability. In addition, there is a secure frequency hopping communication system based on an improved ZUC algorithm. This system improves the security and randomness of the sequence by introducing a permutation polynomial and an evolutionary DES algorithm.

[0004] In summary, although the existing frequency hopping communication technologies have made certain progress in anti-interference, there is still room for improvement in terms of security and anti-interference ability. Summary of the Invention

[0005] Aiming at the defects of the existing technology, the purpose of the present invention is to provide a dynamic wireless key hopping communication anti-interference system and its method.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a dynamic wireless key hopping communication anti-interference system, including a transmitter and a receiver; The transmitter includes: A source scrambling module for performing shift register scrambling on the input information to limit the continuous code length; A Turbo coding module for performing channel coding on the scrambled data; A spreading module for spreading the coded data according to waveform parameters; A framing module for adding a rate code and performing mapping and interleaving according to the QPSK symbol mapping requirements; The frequency hopping pattern generation module generates a random frequency hopping pattern based on a wireless key and the Lorenz chaotic system; The shaping filter module is used for interpolation and square root raised cosine filtering to output the IQ baseband signal; The receiving end includes: The digital front-end processing module filters, digitally down-converts, and performs matched filtering on the received intermediate frequency signal; The frequency hopping synchronization module realizes frequency hopping pattern synchronization by combining coarse synchronization and fine synchronization; The signal synchronization module completes signal acquisition and frequency offset compensation based on the PN sequence correlation; The demodulation module performs despreading, demodulation, and Turbo decoding on the deinterleaved data to recover the original information.

[0007] As a preferred solution, the frequency hopping pattern generation module adopts the Lorenz chaotic system to generate a chaotic sequence through the following differential equations: Chaos is generated when a = 10, b = 28, c = 8 / 3. The initial value of x is set to 1.2, the initial value of y is set to 1.3, the initial value of z is set to 1.6, and the step size is 0.05.

[0008] As a preferred solution, the coarse synchronization of the frequency hopping synchronization module is realized through HTOD correction, and the fine synchronization adjusts the deviation in units of 1 ms to ensure that the frequency hopping patterns of the transceiver parties are consistent.

[0009] As a preferred solution, the signal synchronization module includes segmented phase compensation and synchronization confirmation, and determines the success of synchronization by comparing the correlation amplitude of the PN sequence after coherent demodulation with a threshold.

[0010] This application also provides a dynamic wireless key frequency hopping communication anti-jamming method, which uses the above-mentioned dynamic wireless key frequency hopping communication anti-jamming system, and includes the following steps: S1. The transmitting end performs source scrambling, Turbo coding, spreading, framing, and QPSK mapping on the input information; S2. Generate a dynamic wireless key based on the Lorenz chaotic system to control the random hopping of the frequency hopping pattern; S3. The receiving end realizes frequency hopping pattern matching through digital front-end processing, frequency hopping synchronization, and signal synchronization; S4. Perform deinterleaving, despreading, and Turbo decoding on the demodulated data to recover the original information.

[0011] As a preferred solution, the frequency hopping pattern generation step includes quantizing the chaotic sequence and generating the frequency hopping frequency using a frequency synthesizer.

[0012] The beneficial effects of this application are as follows: 1. The frequency-hopping pattern based on the chaotic system has high randomness and anti-predictability, effectively resisting tracking interference and eavesdropping.

[0013] 2. The combination of coarse and fine synchronization ensures fast synchronization, and matched filtering realizes interference-free reception between codes.

[0014] 3. Multi-level coding and interference cancellation technology enhance communication reliability in complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Flow chart of the transmitter processing of the present invention;

[0016] Figure 2 Flow chart of the receiver processing of the present invention;

[0017] Figure 3 Time-domain sequence diagram of the Lorenz system of the present invention;

[0018] Figure 4 Flow chart of the frequency-hopping pattern generation of the present invention;

[0019] Figure 5 Evolution process of the x sequence of the Lorenz system of the present invention under different initial values DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The embodiment of this application provides a dynamic wireless key frequency-hopping communication anti-jamming system, including a transmitter and a receiver; The transmitter includes: a source scrambling module for scrambling the input information by a shift register to limit the continuous code length; A Turbo coding module for channel coding the scrambled data; A spreading module for spreading the coded data according to waveform parameters; A framing module for adding a rate code and performing mapping and interleaving according to the QPSK symbol mapping requirements; A frequency-hopping pattern generation module for generating a random frequency-hopping pattern based on a wireless key and a Lorenz chaotic system; a shaping filtering module for interpolating and performing square root raised cosine filtering to output an IQ baseband signal; The receiver includes: a digital front-end processing module for filtering, digital down-conversion and matched filtering of the received intermediate frequency signal; A frequency-hopping synchronization module for realizing frequency-hopping pattern synchronization by combining coarse synchronization and fine synchronization; A signal synchronization module for completing signal acquisition and frequency offset compensation based on the PN sequence correlation; The demodulation module performs despreading, demodulation, and Turbo decoding on the deinterleaved data to recover the original information.

[0022] The processing flow chart of the transmitting end of the dynamic wireless key hopping communication anti-jamming system is as Figure 1 shown.

[0023] First, the input information is subjected to source scrambling using a shift register to limit the length of consecutive "0" or consecutive "1" codes. The source-scrambled data is sent to a Turbo encoder for channel coding. The Turbo-coded data is spread spectrum according to the given waveform parameters. The spread-spectrum data is framed by adding a rate code. The data after adding the rate code is mapped according to the QPSK symbol mapping requirements. After symbol mapping, it is interleaved according to the given interleaving table. According to the frame structure and waveform parameter requirements under different rate modes, the data after channel interleaving is framed and hopped by adding a frame header, pilot code, and protection hop information. The data after hopping undergoes interpolation and a square root raised cosine filter to complete the shaping filtering and rate conversion of the baseband signal, and finally, the IQ baseband signal is output.

[0024] The processing flow chart of the receiving end of the dynamic wireless key hopping communication anti-jamming system is as Figure 2 shown.

[0025] The receiving section receives the intermediate-frequency signal after AD sampling, and after a series of operations such as digital front-end processing and QPSK coherent demodulation, the demodulated bit stream is obtained. Specifically:

[0026] (1) Digital front-end processing: The intermediate-frequency signal after AD sampling is first sent to the digital front-end processing module to complete intermediate-frequency filtering, digital down-conversion, sampling rate conversion, and matched filtering, and output the IQ baseband signal according to the oversampling rate. The matched filter uses the same square root raised cosine roll-off filter as the transmitting end. Its main function is to filter out out-of-band noise and form an optimal baseband transmission system with the pulse shaping filter at the transmitting end, so that there is no inter-symbol interference at the receiving end, thereby maximizing the output signal-to-noise ratio and facilitating the accurate extraction of the signal by the backend.

[0027] Frequency Hopping Synchronization: It is achieved by combining coarse synchronization and fine synchronization. Coarse synchronization uses the synchronization frequency obtained by HTOD to complete synchronization capture and the correction of HTOD. In this way, the transmitting and receiving parties will have the same frequency within a certain time deviation range, thus completing coarse synchronization. Fine synchronization realizes the correction of data deviation at the 1ms level, adjusts in units of 1ms, and the synchronization is more accurate and runs through the entire communication process. After that, the master station can send all TOD information, so that the TOD information from the time variable (Time of Day, TOD) will be completely consistent, thus realizing the consistency of frequency hopping in the data transmission stage, that is, the consistency of the frequency hopping pattern. In the frequency hopping pattern generation (PRG) algorithm, the randomness of the frequency hopping pattern depends on the wireless random key. The transmitting and receiving parties extract the wireless key using the physical layer characteristics of the wireless channel, and then use the Lorenz system to generate a chaotic sequence. The Lorenz system is generated by a three-variable nonlinear difference equation system, and its expression is

[0028] Chaos is generated when a = 10, b = 28, c = 8 / 3. Set the initial value of x to 1.2, the initial value of y to 1.3, and the initial value of z to 1.6. Use Matlab for simulation, set the step size to 0.05, and obtain the x time-domain sequence of the Lorenz system as Figure 3 shown. Quantify the generated time-domain sequence to obtain a chaotic sequence, and the chaotic sequence controls the frequency synthesizer to generate a randomly jumping pattern. The algorithms used by the transmitting and receiving parties to calculate the frequency hopping pattern, the chaotic sequences are the same. If the input conditions are the same, the output frequency hopping patterns will also be the same, as Figure 4 shown.

[0029] (3) Signal Synchronization: Signal Capture and Frequency Offset Estimation First, according to the correlation between the received PN sequence and the local PN sequence, realize the coarse synchronization of the signal, and output the captured frequency and phase values. Then, the frequency offset compensation module compensates the captured frequency to the IQ baseband signal. After frequency compensation, calculate the phase rotation amount of the sampled PN sequence (after frequency offset compensation) and the local PN code in segments to obtain the segmented phase compensation values. The segmented phase compensation module compensates the phase compensation values, and finally obtains the baseband signal after frequency offset and phase compensation. To reduce the false alarm probability, finally, the synchronization confirmation module performs coherent demodulation on the received PN sequence, correlates it with the local PN sequence after demodulation, and determines whether the amplitude after correlation is greater than a given threshold. If it is greater than the threshold, it is considered that the synchronization is successful; otherwise, it enters the coarse synchronization again.

[0030] After successful synchronous confirmation, interference rejection is performed, and then the channel deinterleaving module deinterleaves the received data according to the interleaving table. After deinterleaving, the rate code and the physical layer received data are extracted respectively; the rate recognition module discriminates the rate mode; the despreading and demodulation module despreads and demodulates the received data according to the rate mode, and outputs the soft information of QPSK demodulation; the soft information after QPSK demodulation successively undergoes interference rejection, Turbo decoding, source descrambling, and restoration to obtain the demodulated bit stream.

[0031] Chaotic systems exhibit a high sensitivity to initial conditions, and small disturbances can have a huge impact. For this reason, chaotic sequences are unpredictable and errors will inevitably occur at any moment, causing the state at a future moment to deviate from the future state uniquely determined by the deterministic equation under the initial state. Especially during computer simulation, due to the truncation effect caused by data length limitations, errors occur. Therefore, any minor influence is likely to become amplified and exaggerated over time.

[0032] Figure 5 It shows the huge impact on the entire system caused by slight differences in the initial values in the Lorenz system. Among them, the red line represents the initial value of 1.20001, and the blue line represents the initial value of 1.2. At this time, set the x sequence with initial values x0 = 1.2 and x0 = 1.20001. It can be seen from the evolution processes under the two conditions that after the evolution reaches 1500 points, it can be seen that the two orbits quickly diverge.

[0033] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. Dynamic wireless key frequency hopping communication anti-interference system, characterized in that: Includes a transmitter and a receiver; The transmitter includes: The source scrambling module is used to perform shift register scrambling on the input information and limit the continuous code length; Turbo coding module, used for channel coding the scrambled data; A spectrum spreading module, used for spreading the coded data according to waveform parameters; A framing module, used to add rate codes and perform mapping and interleaving according to QPSK symbol mapping requirements; A frequency hopping pattern generation module generates random frequency hopping patterns based on wireless keys and Lorenz chaotic systems; A shaping filter module is used for interpolation and square root raised cosine filtering to output IQ baseband signals; The receiving end includes: The digital front-end processing module performs filtering, digital down-conversion and matched filtering on the received intermediate frequency signal; The frequency hopping synchronization module uses a combination of coarse synchronization and fine synchronization to achieve frequency hopping pattern synchronization; Signal synchronization module, which completes signal capture and frequency offset compensation based on PN sequence correlation; The demodulation module despreads, demodulates and Turbo decodes the deinterleaved data to restore the original information.

2. The dynamic wireless key frequency hopping communication anti-interference system according to claim 1 is characterized in that: The frequency hopping pattern generation module adopts the Lorenz chaotic system to generate a chaotic sequence through the following differential equation: Chaos occurs when a=10, b=28, c=8 / 3, and the initial value of x is set to 1.2, the initial value of y is set to 1.3, the initial value of z is set to 1.6, and the step size is 0.

05.

3. The dynamic wireless key frequency hopping communication anti-interference system according to claim 1 is characterized in that: The coarse synchronization of the frequency hopping synchronization module is achieved through HTOD correction, and the fine synchronization is carried out by adjusting the deviation in units of 1 ms to ensure that the frequency hopping patterns of the transmitter and receiver are consistent.

4. The dynamic wireless key frequency hopping communication anti-interference system according to claim 1 is characterized in that: The signal synchronization module includes segmented phase compensation and synchronization confirmation, and determines whether synchronization is successful by comparing the correlation amplitude of the PN sequence after coherent demodulation with a threshold.

5. A dynamic wireless key frequency hopping communication anti-interference method, using the dynamic wireless key frequency hopping communication anti-interference system according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, the transmitter performs source scrambling, Turbo coding, spectrum spreading, framing and QPSK mapping on the input information; S2, generating dynamic wireless keys based on Lorenz chaotic system to control the random hopping of frequency hopping pattern; S3, the receiving end realizes frequency hopping pattern matching through digital front-end processing, frequency hopping synchronization and signal synchronization; S4. Deinterleave, despread and Turbo decode the demodulated data to restore the original information.

6. The dynamic wireless key frequency hopping communication anti-interference method according to claim 5, characterized in that: The frequency hopping pattern generation step includes quantizing the chaotic sequence and generating the frequency hopping frequency by using a frequency synthesizer.

Images