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CN-122027425-A - TDCS-OFDM hidden communication method and device

CN122027425ACN 122027425 ACN122027425 ACN 122027425ACN-122027425-A

Abstract

The invention discloses a TDCS-OFDM hidden communication method and device, and relates to the technical field of communication. The method comprises the steps of sampling an electromagnetic environment to generate a base function, carrying out coding interleaving on TDCS information of a transformation domain communication system needing communication, modulating coded and interleaved TDCS data by using Cyclic Code Shift Keying (CCSK) to generate a frequency domain TDCS signal loaded on a first subcarrier, wherein the first subcarrier is a subcarrier in an available frequency spectrum range determined based on the base function, carrying out coding interleaving on Orthogonal Frequency Division Multiplexing (OFDM) information needing communication, carrying out orthogonal amplitude modulation on the OFDM information after coding interleaving to generate a frequency domain OFDM signal loaded on a second subcarrier, wherein the second subcarrier is different from the first subcarrier in the available frequency spectrum range, and carrying out frequency domain synthesis, inverse fast Fourier transform and cyclic prefix addition on the frequency domain TDCS signal and the frequency domain OFDM signal in sequence to form a TDCS-OFDM signal. The invention improves the communication rate and the interception resistance of the hidden communication.

Inventors

  • LIU FUYUAN
  • ZHAO ZHIYUE
  • GOU XIN

Assignees

  • 四川九洲电器集团有限责任公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. A method of TDCS-OFDM covert communication, the method comprising: sampling an electromagnetic environment to obtain a spectrum sensing result, and generating a basis function based on the spectrum sensing result; Coding and interleaving the TDCS information of the transformation domain communication system which needs to be communicated; modulating the coded and interleaved TDCS data by using a Cyclic Code Shift Keying (CCSK), and generating a frequency domain TDCS signal for the modulated TDCS data loaded on a first subcarrier based on the basis function and preset subcarrier allocation, wherein the first subcarrier is a subcarrier in an available frequency spectrum range determined based on the basis function; coding and interleaving the Orthogonal Frequency Division Multiplexing (OFDM) information to be communicated; Quadrature amplitude modulating the coded and interleaved OFDM information to generate a frequency domain OFDM signal loaded on a second subcarrier, the second subcarrier being a subcarrier different from the first subcarrier within an available spectral range determined based on the basis function; And sequentially performing frequency domain synthesis, inverse fast Fourier transform and cyclic prefix addition on the frequency domain TDCS signal loaded on the first subcarrier and the frequency domain OFDM signal loaded on the second subcarrier to form a TDCS-OFDM signal.
  2. 2. The method of claim 1, wherein sampling the electromagnetic environment to obtain a spectrum sensing result and generating a basis function based on the spectrum sensing result comprises: calculating an environmental spectrum power spectrum density based on a sampling result of the electromagnetic environment to obtain an environmental spectrum amplitude; and comparing the environmental spectrum amplitude with a preset threshold to determine the frequency band position occupied by interference, and obtaining a basis function amplitude vector.
  3. 3. The method of claim 1, wherein modulating the coded and interleaved TDCS data with the CCSK and generating and loading a frequency domain TDCS signal for the modulated TDCS data on a first subcarrier based on the basis function and a preset subcarrier allocation comprises: converting binary coded and interleaved TDCS data into decimal data and taking the decimal data as a transmitting symbol; CCSK modulation is carried out on the sending symbol so as to generate a frequency domain TDCS signal; Generating a random phase vector with the same length as the base function amplitude vector through a random phase generator, and then carrying out point multiplication on the random phase vector and the base function amplitude vector to obtain a frequency domain expression of a base function; and loading the frequency domain TDCS signal to the first subcarrier by utilizing the preset subcarrier allocation based on the frequency domain TDCS signal and the frequency domain expression of the basis function.
  4. 4. The method according to any one of claims 1 to 3, further comprising adding artificial noise to the frequency domain OFDM signal after quadrature amplitude modulating the encoded interleaved OFDM information to obtain the frequency domain OFDM signal, and loading the frequency domain OFDM signal after adding the artificial noise onto the second sub-carrier.
  5. 5. The method of claim 4, wherein the frequency domain OFDM signal to which the artificial noise is added is: Wherein the added artificial noise is expressed as , A null space matrix representing channel state information of the primary channel, Representing vectors corresponding to the artificial noise; representing a matrix of data signals; Precoding matrix representing secret signal A sub-matrix of the first r columns of (b).
  6. 6. The method of claim 5, wherein the calculating is performed by singular value decomposition of the channel state information 、 And Is a value of (a).
  7. 7. The method of claim 1, wherein the TDCS information and the OFDM information are encoded using a rate 1/2 convolutional encoding.
  8. 8. The method of claim 1, wherein the power of the frequency domain OFDM signal is greater than the power of the frequency domain TDCS signal.
  9. 9. A TDCS-OFDM covert communication device, the device comprising: The base function generation module is used for sampling the electromagnetic environment to obtain a spectrum sensing result and generating a base function based on the spectrum sensing result; The TDCS information coding and interleaving module is used for coding and interleaving the TDCS information of the transform domain communication system which needs to be communicated; The frequency domain TDCS signal generation module is used for modulating the coded and interleaved TDCS data by using a Cyclic Code Shift Keying (CCSK), and generating a frequency domain TDCS signal for the modulated TDCS data loaded on a first subcarrier based on the base function and preset subcarrier allocation, wherein the first subcarrier is a subcarrier in an available frequency spectrum range determined based on the base function; The OFDM information coding and interleaving module is used for coding and interleaving the Orthogonal Frequency Division Multiplexing (OFDM) information which needs to be communicated; The frequency domain OFDM signal generation module is used for carrying out orthogonal amplitude modulation on the OFDM information after coding interleaving to generate a frequency domain OFDM signal loaded on a second subcarrier, wherein the second subcarrier is a subcarrier which is different from the first subcarrier in the available frequency spectrum range determined based on the basis function; And the TDCS-OFDM signal generation module is used for sequentially carrying out frequency domain synthesis, inverse fast Fourier transform and cyclic prefix addition on the frequency domain TDCS signal loaded on the first subcarrier and the frequency domain OFDM signal loaded on the second subcarrier to form the TDCS-OFDM signal.
  10. 10. A TDCS-OFDM covert communication device, the device comprising: At least one processor; At least one memory coupled to the at least one processor and storing instructions for execution by the at least one processor, the instructions when executed by the at least one processor implementing the method of any one of claims 1 to 8.

Description

TDCS-OFDM hidden communication method and device Technical Field The invention relates to the technical field of communication, in particular to a TDCS-OFDM hidden communication method and device. Background At present, related research contents about an OFDM-TDCS (orthogonal frequency division multiplexing-transform domain communication system) communication system comprise code interleaving, synchronization, modulation and demodulation of the system, influence of channels on the system, influence of random subcarriers and continuous subcarriers on the system and the like, but the problems that the system ensures a certain communication rate and has safe communication in the transmission process of the wireless communication system are seldom analyzed. In the communication process, although the OFDM-TDCS system can avoid interference, and select available frequency bands for data communication, so as to improve transmission reliability, the communication speed of the TDCS system is very low in actual communication due to the characteristic of sacrificing high-frequency spectrum resources to exchange communication stability. And if more and more complex interference exists in the environment, the remaining available frequency bands may be fewer, so that the communication rate of the communication system is lower, and accurate interaction of large-capacity information cannot be achieved. Disclosure of Invention Aiming at the problems that the communication rate of the existing hidden communication is low and the eavesdropper has strong signal processing capability and is easy to detect, the invention provides the TDCS-OFDM hidden communication method and the TDCS-OFDM hidden communication device, and improves the communication rate and the interception resistance of the hidden communication. The invention is realized by the following technical scheme. In a first aspect, a TDCS-OFDM covert communication method is provided, the method comprising: sampling an electromagnetic environment to obtain a spectrum sensing result, and generating a basis function based on the spectrum sensing result; Coding and interleaving the TDCS information of the transformation domain communication system which needs to be communicated; modulating the coded and interleaved TDCS data by using a Cyclic Code Shift Keying (CCSK), and generating a frequency domain TDCS signal for the modulated TDCS data loaded on a first subcarrier based on the basis function and preset subcarrier allocation, wherein the first subcarrier is a subcarrier in an available frequency spectrum range determined based on the basis function; coding and interleaving the Orthogonal Frequency Division Multiplexing (OFDM) information to be communicated; Quadrature amplitude modulating the coded and interleaved OFDM information to generate a frequency domain OFDM signal loaded on a second subcarrier, the second subcarrier being a subcarrier different from the first subcarrier within an available spectral range determined based on the basis function; And sequentially performing frequency domain synthesis, inverse fast Fourier transform and cyclic prefix addition on the frequency domain TDCS signal loaded on the first subcarrier and the frequency domain OFDM signal loaded on the second subcarrier to form a TDCS-OFDM signal. In some embodiments, sampling an electromagnetic environment to obtain a spectrum sensing result and generating a basis function based on the spectrum sensing result includes: calculating an environmental spectrum power spectrum density based on a sampling result of the electromagnetic environment to obtain an environmental spectrum amplitude; and comparing the environmental spectrum amplitude with a preset threshold to determine the frequency band position occupied by interference, and obtaining a basis function amplitude vector. In some embodiments, modulating the coded and interleaved TDCS data with the CCSK and generating and loading a frequency domain TDCS signal for the modulated TDCS data on a first subcarrier based on the basis function and a preset subcarrier allocation, comprising: converting binary coded and interleaved TDCS data into decimal data and taking the decimal data as a transmitting symbol; CCSK modulation is carried out on the sending symbol so as to generate a frequency domain TDCS signal; Generating a random phase vector with the same length as the base function amplitude vector through a random phase generator, and then carrying out point multiplication on the random phase vector and the base function amplitude vector to obtain a frequency domain expression of a base function; and loading the frequency domain TDCS signal to the first subcarrier by utilizing the preset subcarrier allocation based on the frequency domain TDCS signal and the frequency domain expression of the basis function. In some embodiments, the method further comprises adding artificial noise to the frequency domain OFDM signal after performing orthogonal