An OTFS secure transmission method, system, device and medium based on common sense integration and frequency domain power distribution

Abstract

An OTFS secure transmission method, system, device, and medium based on integrated induction and frequency domain power allocation; the method involves generating an OTFS transmission frame X with signal-guide fusion. DD After OTFS modulation and up-conversion processing, the transmitted OTFS signal s is obtained. RF (t); Receive user-received OTFS signal s RF (t) and reflect to generate an echo signal. The transmitting end performs OTFS reception and demodulation on the echo signal to obtain the DD domain echo frame estimate of the DD domain channel impulse response; derives the optimal power allocation scheme in the TF domain under secure transmission conditions; builds a channel physical layer security analysis model; the system, equipment and medium are used to implement the method; this invention uses an integrated inductive and communication system based on OTFS modulation to estimate the DD domain channel impulse response using the echo signal, and performs optimal power allocation in the frequency domain through the channel impulse response, thereby improving the signal-to-noise ratio of the received signal and enhancing the security of information transmission.

Description

Technical Field

[0001] This invention belongs to the field of wireless communication technology, and specifically relates to an OTFS secure transmission method, system, device and medium based on inductive integration and frequency domain power allocation. Background Technology

[0002] With the continuous development of wireless communication technology, wireless spectrum resources are becoming increasingly limited. Next-generation wireless communication systems need to reuse radar frequency bands to achieve spectrum sharing between communication and sensing, thereby improving spectrum utilization. In high-mobility scenarios (such as high-speed rail and drones), Orthogonal Frequency Division Multiplexing (OFDM) technology suffers from severe inter-carrier interference due to Doppler shift disrupting the orthogonality of subcarriers. To address this issue, Orthogonal Time-Frequency Space (OTFS) modulation technology has been proposed. OTFS modulation modulates data in the delayed Doppler domain and extends it across the entire time-frequency domain, causing symbols in the transmission unit to experience a slowly changing sparse channel, thus overcoming the problems caused by high Doppler shift.

[0003] The literature [Liu Dong. Research on Power Allocation for Integrated Communication and Sensing Based on OTFS [D]. China University of Mining and Technology, 2023.] proposes to jointly design the integrated communication and sensing signal waveform in the Doppler domain and time delay domain, and also proposes a novel ISAC power allocation method that can serve both the primary radar purpose and the secondary communication purpose. However, due to the waveform design and power allocation in the Doppler domain and time delay domain, problems such as complex structure and limited communication quality arise.

[0004] Patent application CN202110553232 discloses a power allocation method in an OTFS-NOMA cross-domain transmission system. This method solves the power allocation problem between high-speed and low-speed mobile users during signal transmission by reusing the frequency band of high-speed users. However, due to the simultaneous design of low-speed and high-speed users, the power allocation is complex and inefficient.

[0005] Meanwhile, while research on the feasibility, signal detection, and equalization of OTFS systems is relatively thorough, work on achieving secure transmission of OTFS signals is still lacking, considering the vulnerability of wireless communication signals to eavesdropping. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide an OTFS secure transmission method, system, device, and medium based on inductive integration and frequency domain power allocation. Through an inductive integration system based on OTFS modulation, the echo signal is used to estimate the channel impulse response in the DD domain. Based on the channel impulse response, optimal power allocation is performed in the frequency domain, which improves the signal-to-noise ratio of the received signal and thus enhances the security of information transmission.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An OTFS secure transmission method based on inductive integration and frequency domain power allocation includes the following steps:

[0009] Step 1: The OTFS transmitter generates an OTFS transmission frame X with signal-guide fusion. DD Transmission frame X DD After OTFS modulation and up-conversion processing, the OTFS signal s transmitted by the transmitting antenna is obtained. RF (t);

[0010] Step 2: Receive the OTFS signal s sent by the user in step 1. RF (t) and reflect to generate an echo signal. The transmitter performs OTFS reception and demodulation on the echo signal to obtain the DD domain echo frame.

[0011] Step 3: Use the OTFS transfer frame X generated in Step 1 DD and the DD domain echo frame obtained in step 2 Estimate the channel impulse response in the DD domain;

[0012] Step 4: Based on the estimated DD domain channel impulse response in Step 3, derive the optimal power allocation scheme in the TF domain under secure transmission conditions;

[0013] Step 5: Based on the optimal power allocation scheme in the TF domain from Step 4, build a channel physical layer security analysis model.

[0014] The specific method for step 1 is as follows:

[0015] A two-dimensional planar grid in the TF domain is obtained by sampling along the time and frequency axes, defined as Λ = (nT, mΔf), where T and Δf represent the sampling intervals along the time and frequency axes, respectively, with corresponding sampling points of N and M. The indices for the time and frequency domains are represented by n = 0, 1, ..., N-1 and m = 0, 1, ..., M-1. Similarly, a two-dimensional planar grid in the DD domain is obtained by sampling along the delay and Doppler axes, defined as Γ = (k / (NT), l / (MΔf)), where k / (NT) and MΔf represent the sampling intervals along the delay and Doppler axes, respectively, with l = 0, 1, ..., M-1 and k = 0, 1, ..., N-1 representing the indices for the delay and Doppler domains. The total duration of an OTFS data frame in the TF domain two-dimensional planar grid is T. f =NT, the total bandwidth is B=MΔf, where N and M correspond to the number of OTFS symbols and the number of subcarriers respectively, T and Δf represent the OTFS symbol period and the subcarrier spacing respectively, and TΔf=1 is satisfied to maintain the orthogonality of the multicarriers;

[0016] At the OTFS transmitter, information symbols are used to transmit information, and pilot symbols are used for subsequent signal estimation; the information symbols and pilot symbols are arranged into a two-dimensional matrix. And placed on the two-dimensional planar grid Γ in the DD domain, where X is the DD domain transmitted modulation symbol matrix; two-dimensional matrix After undergoing Quadrature Amplitude Modulation (QAM), the OTFS transmission frame is obtained.

[0017] Send OTFS transfer frame X DD The TF-domain transmitted modulation symbol matrix is ​​obtained by mapping using the Inverse Symplectic Finite Fourier Transform (ISFFT). Transmit modulation symbol matrix The time-frequency grid points corresponding to the N symbols and M subcarriers occupying the two-dimensional planar grid Λ in the TF domain are specifically as follows:

[0018]

[0019] Among them, X TF [n, m]∈X TF This represents the transmitted modulation symbol at the nth time-domain and mth frequency-domain index grid point on the TF-domain two-dimensional planar grid Λ;

[0020] Then for X TF The OTFS inductive integrated time-domain baseband signal is obtained by applying the Heisenberg Transform to [n, m].

[0021]

[0022] Among them, g tx (t) represents the transmitted pulse, and T and Δf represent the sampling intervals of the time and frequency axes, respectively;

[0023] The baseband signal s(t) is RF modulated to obtain the up-converted RF signal, which is the OTFS signal s transmitted by the transmitting antenna. RF (t);

[0024]

[0025] Wherein, the radio frequency carrier frequency is f c .

[0026] The specific method for step 2 is as follows:

[0027] The echo signal received by the transmitting antenna is After down-conversion, the time-domain baseband received signal is obtained, namely:

[0028]

[0029] Wherein, the radio frequency carrier frequency is f c Then to The TF-domain received modulation symbol matrix is ​​obtained by applying the Wigner transform.

[0030]

[0031] in, This represents the received modulation symbol at the nth time-domain index and the mth frequency-domain index grid point on the two-dimensional planar grid Λ in the TF domain, and the receiver uses the same rectangular pulse shaping filter. * indicates the complex conjugate function, and T and Δf represent the sampling intervals of the time and frequency axes, respectively.

[0032] After the Wegener transform, the Symptotic Finite Fourier Transform (SFFT) is used to... Inverse mapping yields DD domain echo frames

[0033] in, This represents the echo frame at the k-th Doppler domain index and the l-th time delay domain index grid point on the DD domain two-dimensional planar grid Γ.

[0034] The specific method for step 3 is as follows:

[0035] In the DD domain, the OTFS transport frame X generated in step 1 DD Compared with the DD domain echo frame obtained in step 2 The relationship between the channel impulse response hDD[k′, l′] and the channel impulse response hDD[k′, l′] is as follows:

[0036]

[0037] Among them, h DD [k′, l′] is the DD domain channel impulse response, describing the channel gain of the signal at a specific delay l′ and Doppler shift k′, where k v , l τ This represents the maximum Doppler shift and delay. The term has a variance of σ. 2 Additive white noise;

[0038] Channel estimation is performed using least squares (LS) estimation:

[0039]

[0040] in, It is the conjugate of the transmitted signal-guided frame, |X DD [kk′,ll′]| 2 It is the power of the transmitted signal-guided frame;

[0041] The entire process of the transmitted frame being reflected by the receiving user to the transmitting end for receiving the echo signal involves two round trips. The DD domain sensing channel will experience double delay spread and double Doppler shift, while the channel complex gain is related to the gain of the transmitting and receiving antennas; that is, the estimated DD domain channel impulse response is:

[0042]

[0043] The specific method for step 4 is as follows:

[0044] The estimated DD domain channel impulse response in step 3 is shown in equation (9). The DD domain channel impulse response is converted into the TF domain channel impulse response by inverse symplectic finite Fourier transform (ISFFT):

[0045]

[0046] Among them, H TF [n, m] represents the channel gain at each sampling point (n, m) in the TF domain, using H f The channel state in the TF domain is represented by an N*M diagonal matrix, where the (nM+m+1)th element is H. TF [n, m];

[0047] After the Wigner transform, zero-forcible equalization (ZF equalization) is applied to the OTFS frequency domain signal. The frequency domain signal after zero-forcible equalization (ZF equalization) is as follows:

[0048]

[0049] Among them, Y′ TF To receive the frequency domain signal after the Wigner transform at the receiving end;

[0050] The quality of the received signal is expressed using the signal-to-noise ratio of the received signal.

[0051]

[0052] Among them, YD D The DD domain signal received by the receiving signal terminal after OTFS demodulation;

[0053] To achieve secure transmission by allocating power in the TF domain, then:

[0054] Y TF =(E*H f ) -1 *Y′ TF (13)

[0055] Where E is the power allocation matrix, and thus, in the case of power allocation in the frequency domain, the signal-to-noise ratio of the received signal is:

[0056]

[0057] Without knowing that the user's channel information is being eavesdropped on, the goal of securely transmitting channel information is to maximize the difference between the received signal-to-noise ratio and the received signal-to-noise ratio.

[0058] Max(SNR E -SNR X (15)

[0059] exist Under the total power constraint, to minimize the expected noise value, the optimal power allocation scheme in the TF domain calculated using the Lagrange multiplier is:

[0060]

[0061] Among them, H TF [n, m] represents the channel gain at each sampling point (n, m) in the TF domain.

[0062] The specific method for step 5 is as follows:

[0063] Security rate is a key indicator for measuring the security performance of a communication system, reflecting the system's ability to resist eavesdropping attacks;

[0064] The safe rate is calculated as follows:

[0065] R s =[C m -C e ] + (17)

[0066] Where, [x] + =max(x, 0), where C is the channel capacity, representing the maximum rate at which the channel can carry information, usually calculated using Shannon's theorem: Where C is the channel capacity, B is the bandwidth, S is the signal power, N is the noise power, and C m The primary channel capacity is the channel capacity for legitimate users receiving information. It is obtained by calculating the primary channel capacity, C. eEavesdropping channel capacity: This is the channel capacity when an eavesdropper receives information, and it is obtained by calculating the channel capacity of the eavesdropping channel.

[0067] This invention also provides an OFFS secure transmission system based on inductive integration and frequency domain power allocation, comprising:

[0068] The OTFS modulation module is used by the OTFS transmitter to generate the signal-guide fusion OTFS transmission frame X. DD Transmission frame X DD After OTFS modulation and up-conversion processing, the OTFS signal s transmitted by the transmitting antenna is obtained. RF (t);

[0069] The OTFS demodulation module is used to receive the OTFS signal received by the user. RF (t) and reflect to generate an echo signal. The transmitter performs OTFS reception and demodulation on the echo signal to obtain the DD domain echo frame.

[0070] DD domain channel impulse response estimation module, used to utilize OTFS transmission frame X DD and DD domain echo frames Estimate the channel impulse response in the DD domain;

[0071] The frequency domain power allocation module is used to derive the optimal power allocation scheme in the TF domain under secure transmission conditions based on the estimated DD domain channel impulse response.

[0072] The channel physical layer security analysis module is used to implement the optimal power allocation scheme based on the TF domain and build a channel physical layer security analysis model.

[0073] The present invention also provides an OFFS secure transmission device based on inductive integration and frequency domain power allocation, comprising:

[0074] Memory: A computer program that stores the above-mentioned OTFS secure transmission method based on inductive integration and frequency domain power allocation, and is a computer-readable device;

[0075] Processor: Used to implement the OFFS secure transmission method based on inductive integration and frequency domain power allocation when executing the computer program.

[0076] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, enables the implementation of the aforementioned OFFS secure transmission method based on inductive integration and frequency domain power allocation.

[0077] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0078] 1. This invention proposes an OTFS secure transmission method based on inductive integration and frequency domain power allocation. This method generates an echo signal while receiving the signal, which is used for DD domain channel impulse response estimation. The receiving user uses the relevant parameters of the channel estimation to perform OTFS demodulation and performs optimal power allocation in the frequency domain, thereby reducing the bit error rate of the receiving user and improving the security of information transmission.

[0079] 2. This invention constructs a channel physical layer security analysis model to intercept signals received by eavesdropping users and performs related demodulation. Simulation results show that, compared with legitimate users, legitimate users have a significantly lower bit error rate and a more stable and secure data rate. A comparison between legitimate users with and without frequency domain power allocation shows that users with power allocation have a higher secure data rate and stronger communication security.

[0080] In summary, this invention provides an OTFS secure transmission method, system, device, and medium based on integrated induction and frequency domain power allocation. It utilizes echo signals to estimate the DD domain channel impulse response and performs optimal frequency power allocation at the transmitting end, which has the advantages of reducing bit error rate and improving secure transmission rate. Attached Figure Description

[0081] Figure 1 This is a flowchart of the present invention.

[0082] Figure 2 This is a modulation flowchart of the OTFS signaling transmission frame of the present invention.

[0083] Figure 3 This is a distribution diagram of the pilot, guard, and data symbols arranged in the delayed Doppler grid of the OTFS signal-guided transmission frame of the present invention.

[0084] Figure 4 This is a distribution diagram of the echo signal data and channel estimation symbols in the delayed Doppler grid of the present invention.

[0085] Figure 5 This invention describes the process by which the user receives the OTFS signal and generates an echo signal.

[0086] Figure 6 This is a flowchart illustrating the demodulation process of received signals by legitimate users and eavesdropping users in this invention.

[0087] Figure 7 This is a simulation result graph showing the bit error rate (BER) of the received signals for legitimate users and eavesdropping users under different signal-to-noise ratios (SNR).

[0088] Figure 8 The secure rate (R) for legitimate users and eavesdropping users. sThe simulation results are shown in the figure. Detailed Implementation

[0089] The technical solution adopted by the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0090] This invention provides an OTFS secure transmission method based on integrated sensing and frequency domain power allocation. The method first maps the signal to the delay-Doppler domain (DD domain) through OTFS modulation. Combining communication and sensing functions, the echo signal is used to estimate the DD domain channel impulse response. Subsequently, based on this channel impulse response, optimal power allocation is performed at the transmitting end, effectively improving the signal-to-noise ratio (SNR) of the received signal, thereby enhancing communication security. Further verification of the physical layer security, simulation results show that as the transmitted signal-to-noise ratio (SNR) increases, the secure rate of legitimate users is consistently higher than that of eavesdropping users, significantly improving the system's anti-eavesdropping capability and secure transmission performance.

[0091] See Figure 1 The diagram shows a flowchart of an OTFS secure transmission method based on integrated sensing and frequency domain power allocation, provided by an embodiment of the present invention. This embodiment utilizes echo signals for channel estimation and frequency domain power allocation at the receiving end to improve the security of information transmission. It includes at least the following steps:

[0092] OTFS modulation involves processing and transformation in the time-frequency domain (TF domain) and the delayed Doppler domain (DD domain).

[0093] Step 1: At the OTFS transmitter, information symbols are generated by the information source. To reduce estimation errors, this invention places two pilot signals in the pilot-signal frame, selecting grid positions [k]. p1 , l p1 ] and [k p2 , l p2 Place 1, where 0 ≤ k p1 k p2 ≤N-1,0≤l p1 , l p2 ≤M-1. In l p1 -l τ ≤l≤l p1 +l τ k p1 -2k v ≤k≤k p1 +2k v The other positions are set to 0 as guard symbols. These guard symbols ensure that the received symbols used for channel estimation and data detection do not interfere with each other, and are used to estimate the impulse response in the DD domain of the wireless channel. Where l τ and k vThis represents the tap corresponding to the maximum delay and Doppler value. The information symbols and pilot symbols are arranged into a two-dimensional matrix. And placed on the two-dimensional planar grid Γ of the DD domain, where X is the DD domain transmitted modulation symbol matrix. Two-dimensional matrix. After undergoing Quadrature Amplitude Modulation (QAM), the OTFS transmission frame is obtained. Distribution map as follows Figure 3 As shown. OTFS signal-guided frames are generated using information symbols and pilot symbols. The flowchart of the generated process is as follows. Figure 2 As shown. First, through the Inverse Symplectic Finite Fourier Transform (ISFFT) of Equation (1) and the Heisenberg Transform of Equation (2), the OTFS signal-guided frame is transformed from the DD domain to the TF domain, and then converted into a transmitted signal through the up-conversion transformation of Equation (3).

[0094] Step 2: The transmitter sends an OTFS signal and simultaneously receives the reflected echo signal. The process for receiving the echo signal is as follows: Figure 5 As shown. For the echo signal received by the transmitting antenna, the time-domain baseband received signal is first obtained by down-conversion processing using equation (4). Then, the TF domain received modulation symbol matrix is ​​obtained by applying the Wigner transform equation (5). Subsequently, the DD domain echo frame is obtained by performing a symptotic finite Fourier transform (SFFT) using equation (6). The distribution of the received echo frames is as follows Figure 4 As shown.

[0095] Step 3: Based on the OTFS transfer frame X generated in Step 1 DD and the DD domain echo frame obtained in step 2 Establish transmission frame X using equation (7) DD With echo frame and channel impulse response h DD The relationship between [k′, l′], in practical cases, is the channel impulse response h in the DD domain. DD [k′, l′] is typically sparse, meaning the channel exists only over a finite number of delays l′ and Doppler shifts k′. In this case, the present invention utilizes the sparsity of the signal to further optimize the estimation process. Using Equation (8), a more stable channel estimate is obtained in noisy conditions.

[0096] Meanwhile, it should be noted that because the transmission frame undergoes two round trips from the receiving user to the transmitting end to receive the echo signal, compared with the one-way propagation from the transmitting end to the receiving user, the DD domain sensing channel will experience the effects of double time delay spread and double Doppler frequency shift, while the channel complex gain is related to the gain of the transmitting and receiving antennas; that is, the estimated DD domain channel impulse response h[k, l] can be calculated by equation (9).

[0097] Because this invention places two pilot signals in the signal-guide frame, the position is in [k p1 , l p1 ] and [k p2 , l p2 The channel estimates calculated using equation (8) for the two pilots are respectively... and The final DD domain channel impulse response, combined with equation (9), is:

[0098] Step 4: Based on the estimated DD domain channel impulse response in Step 3, derive the optimal power allocation scheme in the TF domain under secure transmission conditions;

[0099] The estimated DD-domain channel impulse response in step 3 is converted into the TF-domain channel impulse response using equation (10). TF [n, m] represents the channel gain at each sampling point (n, m) in the TF domain. To represent the channel state information of the entire TF grid and facilitate subsequent fast calculations, H is used. f This indicates the channel state of the TF domain. H f Given an N*M diagonal matrix, the (nM+m+1)th element is H. TF [n, m]; Due to inter-symbol interference (ISI) caused by the channel, after the Wigner transform, zero-forcible equalization (ZF equalization) is applied to the OTFS frequency domain signal using equation (11). ZF equalization is a classic linear equalization method. The core idea is to completely eliminate the distortion of the signal after passing through the channel by using the inverse channel matrix, thereby restoring the original transmitted signal. ZF equalization can completely eliminate the inter-symbol interference introduced by the channel, but it will amplify the noise at the same time. In order to analyze and quantify the impact of noise on the system output, the received signal-to-noise ratio expressed in equation (12) is used to represent the quality of the received signal.

[0100] In the OTFS scheme with an FD-ZF equalizer, all symbols in the DD domain experience almost the same channel fading, so the benefit of power allocation in the DD domain is negligible. Power allocation only needs to be performed in the TF domain. Using equations (13)(14)(15) and under the total power constraint, the optimal power allocation scheme in the TF domain is calculated using the Lagrange multiplier in equation (16), and the optimal power allocation operation is performed at the transmitter. The specific implementation process is as follows: Figure 6 As shown, the signal received by the receiving user first undergoes time-frequency analysis (Wigner transform), then zero-forcible equalization (ZF equalization), followed by SFFT transform to recover the signal, then QAM demodulation, and finally received by the legitimate user.

[0101] Step 5: Based on the optimal power allocation scheme in the TF domain from Step 4, construct a channel physical layer security analysis model. In communication systems, the eavesdropping channel model typically describes a situation where an unauthorized user (i.e., an eavesdropper) attempts to intercept and decode communication information between legitimate users. In this model, the source information is encoded by an encoder and transmitted through the main channel to the legitimate user's decoder, where it is ultimately received and decoded by the legitimate user. The eavesdropping channel, on the other hand, represents an unauthorized path through which the eavesdropper obtains the encoded information and attempts to recover the original information using its decoder.

[0102] Security rate is a key indicator for measuring the security performance of a communication system, reflecting its ability to resist eavesdropping attacks. A higher security rate means that it is more difficult for eavesdroppers to successfully decode information, thereby enhancing communication security. In fields with extremely high information security requirements, such as military communications and financial transactions, ensuring a high security rate is particularly important, as it can effectively prevent information leakage and data theft. The calculation method for security rate is shown in equation (17). In this invention, the signal bandwidth B is set to 1MHz, and the channel impulse response of the eavesdropper is set to a random complex number, thereby simulating the security rate performance under different channel conditions.

[0103] Thus, steps 1 to 5 complete the OTFS secure transmission method based on inductive integration and frequency domain power allocation in this embodiment.

[0104] Figure 7 This is a graph showing the received signal bit error rate (BER) under different signal-to-noise ratios (SNRs), based on the inventive scheme proposed in step 4, the scheme without frequency domain power allocation, and the scheme of eavesdropping on the user's received demodulated and transmitted information. It assumes the sender has 2 antennas, the legitimate user has 2 antennas, and the eavesdropping user has 1 antenna. The OTFS modulation subcarrier number N = 16, the time slot number M = 16, and the maximum delay l... τ The maximum Doppler k is 2. pThe value is 2, and the maximum speed is 300 km / h. (From...) Figure 7 It can be seen that the bit error rate (BER) of information received by legitimate users is significantly lower than that of eavesdropping users, and the bit error rate of the power allocation method proposed in this invention is lower than that of the method without power allocation.

[0105] Figure 8 This demonstrates the system's security rate (R) when legitimate users and eavesdropping users receive and demodulate information, based on the same transmitted signal. s The relationship between the signal and the transmitted signal-to-noise ratio (SNR) is shown, with the signal bandwidth B set to 1MHz. These simulation results are based on physical layer security analysis and are primarily used to evaluate the system's anti-eavesdropping performance. In this invention, the channel impulse response of the eavesdropping user is set to a random complex number, which simulates the complex channel conditions that eavesdroppers may face in different scenarios. Figure 6 As shown, both legitimate users and eavesdropping users perform ZF equalization on the frequency domain signal after the Wegener transform. Subsequently, symplectic finite Fourier transform and constellation demapping are performed to recover the 0 and 1 bit streams. Figure 8 Simulation results show that as the transmitted signal SNR increases, the physical layer security rate of legitimate users is consistently higher than that of eavesdropping users. This means that in this invention, legitimate users can securely transmit data at a higher rate, while eavesdropping users, even if they receive the signal, struggle to decode it effectively, thus improving the system's secure transmission performance. In contrast, the channel quality of eavesdropping users is further degraded, resulting in even worse decoding performance. However, the decoding performance is improved after power allocation in this invention, further enhancing the system's security.

[0106] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0107] This invention also provides an OTFS secure transmission system based on inductive integration and frequency domain power allocation, comprising:

[0108] The OTFS modulation module is used to generate the signal-guide fusion OTFS transmission frame X at the OTFS transmitter in step 1. DD Transmission frame X DD After OTFS modulation and up-conversion processing, the OTFS signal s transmitted by the transmitting antenna is obtained. RF (t);

[0109] The OTFS demodulation module is used to receive the OTFS signal s sent by the user in step 1 in step 2.RF (t) and reflect to generate an echo signal. The transmitter performs OTFS reception and demodulation on the echo signal to obtain the DD domain echo frame.

[0110] The DD domain channel impulse response estimation module is used to implement the OTFS transmission frame X generated in step 1 in step 3. DD and the DD domain echo frame obtained in step 2 Estimate the channel impulse response in the DD domain;

[0111] The frequency domain power allocation module is used to derive the optimal power allocation scheme in the TF domain under secure transmission conditions based on the estimated DD domain channel impulse response in step 3 in step 4.

[0112] The channel physical layer security analysis module is used to implement the optimal power allocation scheme based on the TF domain in step 4 in step 5 and to build a channel physical layer security analysis model.

[0113] The present invention also provides an OTFS secure transmission device based on inductive integration and frequency domain power allocation, comprising:

[0114] Memory: A computer program that stores the above-mentioned OTFS secure transmission method based on inductive integration and frequency domain power allocation, and is a computer-readable device;

[0115] Processor: Used to implement the OTFS secure transmission method based on inductive integration and frequency domain power allocation when executing the computer program.

[0116] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, enables the implementation of the OTFS secure transmission method based on inductive integration and frequency domain power allocation.

Claims

1. An OTFS secure transmission method based on inter-sensory integration and frequency domain power allocation, characterized in that, Includes the following steps: Step 1: The OTFS transmitter generates an OTFS transmission frame with signal-guide fusion. Transmission frame After OTFS modulation and up-conversion processing, the OTFS signal transmitted by the transmitting antenna is obtained. ; Step 2: Receive the OTFS signal sent by the user in step 1. The echo signal is reflected and generated. The transmitter performs OTFS reception and demodulation on the echo signal to obtain the DD domain echo frame. ; Step 3: Use the OTFS transfer frame generated in Step 1 and the DD domain echo frame obtained in step 2 Estimate the channel impulse response in the DD domain; Step 4: Based on the estimated DD domain channel impulse response in Step 3, derive the optimal power allocation scheme in the TF domain under secure transmission conditions; The specific method for step 4 is as follows: The estimated DD domain channel impulse response in step 3 is then converted into the TF domain channel impulse response using an inverse symplectic finite Fourier transform (ISFFT). (10) in, Represents each sampling point in the TF domain. Channel gain at that location, using The channel state in the TF domain is represented by an N*M diagonal matrix, the first of which is... The elements are ; After performing a Wigner transform on the echo signal, zero-forcible equalization is applied to the OTFS frequency domain signal. The frequency domain signal after zero-forcible equalization is: (11) in, To receive the frequency domain signal after the Wigner transform at the receiving end; The quality of the received signal is expressed using the signal-to-noise ratio of the received signal. (12) in, The DD domain signal received by the receiving signal terminal after OTFS demodulation; To achieve secure transmission by allocating power in the TF domain, then: (13) Where E is the power allocation matrix, and thus, in the case of power allocation in the frequency domain, the signal-to-noise ratio of the received signal is: (14) Without knowing that the user's channel information is being eavesdropped on, the goal of securely transmitting channel information is to maximize the difference between the received signal-to-noise ratio and the received signal-to-noise ratio. (15) exist Under the total power constraint, to minimize the expected noise value, the optimal power allocation scheme in the TF domain calculated using the Lagrange multiplier is: (16) in, Represents each sampling point in the TF domain. Channel gain at the location; Step 5: Based on the optimal power allocation scheme in the TF domain from Step 4, build a channel physical layer security analysis model; The specific method for step 5 is as follows: Security rate is a key indicator for measuring the security performance of a communication system, reflecting the system's ability to resist eavesdropping attacks; The safe rate is calculated as follows: (17) in, C is the channel capacity, representing the maximum rate at which the channel can carry information, usually calculated according to Shannon's theorem: ,in, It is channel capacity. It's bandwidth. It is signal power. It is noise power. The primary channel capacity is the channel capacity available to legitimate users when receiving information. It is obtained by calculating the primary channel capacity. Eavesdropping channel capacity: This is the channel capacity when an eavesdropper receives information, and it is obtained by calculating the channel capacity of the eavesdropping channel.

2. The OTFS secure transmission method based on inductive integration and frequency domain power allocation according to claim 1, characterized in that, The specific method for step 1 is as follows: A two-dimensional planar grid in the TF domain is obtained by sampling the time and frequency axes, defined as follows: ,in, and These represent the sampling intervals for the time and frequency axes, respectively, with corresponding sampling points of N and M. and , representing the index in the time and frequency domains; similarly, sampling the time delay and Doppler axis yields a two-dimensional planar grid in the DD domain, defined as ,in, and These represent the sampling intervals along the time delay and the Doppler axis, respectively. and Indicates the latency and Doppler domain index; the total duration of an OTFS data frame in the TF domain two-dimensional planar raster is Total bandwidth is , at this time and These correspond to the number of OTFS symbols and the number of subcarriers, respectively. and Let these represent the OTFS symbol period and subcarrier spacing, respectively, and satisfy the following conditions: To maintain the orthogonality of multiple carriers; At the OTFS transmitter, information symbols are used to transmit information, and pilot symbols are used for subsequent signal estimation; the information symbols and pilot symbols are arranged into a two-dimensional matrix. And placed in the DD domain two-dimensional planar grid superior, The modulation symbol matrix for transmitting in the DD domain; a two-dimensional matrix. After undergoing quadrature amplitude modulation (QAM), an OTFS transmission frame is obtained. ; Send OTFS transfer frames Obtained through symplectic finite Fourier inverse transform (ISFFT) mapping Domain transmission modulation symbol matrix Transmit modulation symbol matrix Will occupy Domain Two-Dimensional Plane Grid On a symbol and The time-frequency grid points corresponding to each subcarrier are as follows: (1) in, express Domain Two-Dimensional Plane Grid The first The time domain and the first Transmitted modulation symbols at each frequency domain index grid point; Then to Obtaining the OTFS integrated inductive time-domain baseband signal using Heisenberg transform: (2) in, Indicates the transmission of a pulse. and These represent the sampling intervals for the time and frequency axes, respectively. For baseband signals Radio frequency modulation yields the up-converted radio frequency signal, which is the OTFS signal transmitted by the transmitting antenna. ; (3) Among them, the radio frequency carrier frequency is .

3. The OTFS secure transmission method based on inductive integration and frequency domain power allocation according to claim 1, characterized in that, The specific method for step 2 is as follows: The echo signal received by the transmitting antenna is After down-conversion, the time-domain baseband received signal is obtained, i.e.: (4) Among them, the radio frequency carrier frequency is Then to Applying the Wigner transform, we obtain Domain received modulation symbol matrix : (5) in, express Domain Two-Dimensional Plane Grid The first The time domain index and the first The received modulation symbols are located at each frequency domain index grid point, and the same rectangular pulse shaping filter is used at the receiver. This indicates the search for the complex conjugate function. and These represent the sampling intervals for the time and frequency axes, respectively. After the Wegener transform, the symplectic finite Fourier transform (SFFT) is used to... Inverse mapping yields DD domain echo frames : (6) in, Represents a two-dimensional planar grid in the DD domain. The first The Doppler domain index and the first Echo frames at each time delay domain index grid point.

4. The OTFS secure transmission method based on inductive integration and frequency domain power allocation according to claim 1, characterized in that, The specific method for step 3 is as follows: In the DD domain, the OTFS transport frame generated in step 1 The DD domain echo frame obtained in step 2 and channel impulse response The relationship between them is: （7） in, It is the channel impulse response in the DD domain, describing the signal at a specific delay. and Doppler shift Channel gain at that location, This represents the maximum Doppler shift and delay. The term has a variance of Additive white noise; Channel estimation is performed using least squares estimation (LS): （8） in, It is the conjugate of the transmitted signal-guided frame. It is the power of the transmitted signal-guided frame; The entire process of the transmitted frame being reflected by the receiving user to the transmitting end for receiving the echo signal involves two round trips. The DD domain sensing channel experiences double the time delay spread and double the Doppler frequency shift, while the channel complex gain is related to the gain of the transmitting and receiving antennas; that is, the estimated DD domain channel impulse response is: （9）。 5. An OTFS secure transmission system based on inductive integration and frequency domain power allocation, according to the method of any one of claims 1 to 4, characterized in that, include: O The TFS modulation module is used by the OTFS transmitter to generate OTFS transmission frames with signal-guide fusion. Transmission frame After OTFS modulation and up-conversion processing, the OTFS signal transmitted by the transmitting antenna is obtained. ; The OTFS demodulation module is used to receive OTFS signals received by the user. The echo signal is reflected and generated. The transmitter performs OTFS reception and demodulation on the echo signal to obtain the DD domain echo frame. ; DD domain channel impulse response estimation module, used to utilize OTFS transmission frames and DD domain echo frames Estimate the channel impulse response in the DD domain; The frequency domain power allocation module is used to derive the optimal power allocation scheme in the TF domain under secure transmission conditions based on the estimated DD domain channel impulse response. The channel physical layer security analysis module is used to implement the optimal power allocation scheme based on the TF domain and build a channel physical layer security analysis model.

6. An OTFS secure transmission device based on inductive integration and frequency domain power allocation, characterized in that: include: Memory: A computer program for an OTFS secure transmission method based on inductive integration and frequency domain power allocation as described in any one of claims 1-4, and is a computer-readable device; Processor: Used to implement the OTFS secure transmission method based on inductive integration and frequency domain power allocation as described in any one of claims 1-4 when executing the computer program.

7. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that, when executed by a processor, enables the implementation of the OTFS secure transmission method based on inductive integration and frequency domain power allocation as described in any one of claims 1-4.

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