Signal Modulation Method Based on Weighted Fractional Fourier Transform and Energy Spread Transform

A technology of fractional Fourier transform and energy expansion, which is applied in the field of signal modulation based on weighted fractional Fourier transform and energy expansion transform, which can solve the problem of poor anti-intercept effect

Active Publication Date: 2016-08-17
HARBIN INST OF TECH +1
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Problems solved by technology

[0003] The present invention is to solve the problem of poor anti-interception effect when the signal intercepting party adopts WFRFT demodulation and the transformation order tracking is more accurate when the variable parameter mixed carrier signal of multi-parameter fractional Fourier transform is adopted, and a method based on weighted fractional Fourier transform is provided. And the signal modulation method of energy expansion transformation

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  • Signal Modulation Method Based on Weighted Fractional Fourier Transform and Energy Spread Transform
  • Signal Modulation Method Based on Weighted Fractional Fourier Transform and Energy Spread Transform
  • Signal Modulation Method Based on Weighted Fractional Fourier Transform and Energy Spread Transform

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specific Embodiment approach 1

[0038] Specific embodiment 1: The signal modulation method based on weighted fractional Fourier transform and energy expansion transform in this embodiment includes:

[0039] 1. Construct an energy expansion transformation matrix, and perform energy expansion transformation on a source information symbol sequence s of length N;

[0040] In the step 1, performing energy expansion transformation on a source information symbol sequence s with a length of N is specifically:

[0041] According to the principle of energy expansion transformation, the energy expansion transformation of a source information symbol sequence s of length N can be expressed as:

[0042] x=Es=P μ U μ P μ-1 U μ-1 …P 1 U 1 s, (1)

[0043] where E=P μ U μ …P 1 U 1 represents the energy expansion transformation matrix, P l represents a pseudorandom permutation matrix, where l=1,...,μ,U l represents a normalized orthogonal matrix;

[0044] Based on the construction principle of the traditional ene...

specific Embodiment approach 2

[0063] Embodiment 2: The difference between this embodiment and Embodiment 1 is that the energy spreading, transformation and modulation of the source information symbol sequence s in the second step is specifically:

[0064] (1) First, do α for the source information symbol sequence s 1 order of WFRFT;

[0065] (2) Then the obtained sequence is permuted according to the pseudo-random matrix P 1 Do random interleaving;

[0066] (3) Do the second-level α on the interleaved sequence 2 Order WFRFT, for the resulting sequence according to the pseudo-random permutation matrix P 2 Do random interleaving processing; and so on, until the μ-th stage of WFRFT and interleaving processing is completed, the modulated sequence x is obtained; wherein the transformation order α of each stage of WFRFT l (1≤l≤μ) and the structure of the pseudo-random interleaver is controlled by the sender to change periodically over time.

[0067] Other steps and parameters are the same as in the first em...

specific Embodiment approach 3

[0068] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that: in step 3, the signal receiving end performs inverse energy expansion transformation on the signal to be demodulated y to realize the demodulation process to restore the estimated value of the source information symbol sequence s Specifically:

[0069] (1) The modulated sequence x is sent after digital / analog conversion and up-conversion to high frequency, and reaches the receiving end through the channel. After processing, the signal y to be demodulated is obtained;

[0070] (2) The receiving end of the communication system knows that the transformation order of each stage of WFRFT at the transmitting end and the structure of the pseudo-random interleaver change with time, and the receiving end also knows the change period, so it can be reversed by energy expansion such as formula (3). The transformation process obtains an estimate of the source information symbol sequence s

[007...

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Abstract

The invention relates to a signal modulation method applied to the field of anti-interference and secure communication and discloses a signal modulation method based on weighted-type fractional Fourier transform and energy spreading transform, to solve the problem that a signal interception party adopts WFRFT (weighted-type fractional Fourier transform) and transform order tracking is relatively accurate, the anti-interception effect is poor when variable-parameter mixed carrier signals of multi-parameter fractional Fourier transform are adopted. The signal modulation method comprises the following steps of: 1, establishing an energy spreading transform matrix; 2, performing multistage tandem weighted-type fractional Fourier transform and pseudo-random interleaving process at a sending end; 3, processing a modulated sequence x through a channel cancellation technology (such as channel equalization, channel coding and decoding technologies and the like) to obtain a signal y to be modulated, and performing inverse transform on the signal y to be modulated by a signal receiving end to realize a demodulation process and restore an estimated value of a source information sequence. The signal modulation method disclosed by the invention is applied to the field of secure communication.

Description

technical field [0001] The invention relates to a signal modulation method applied to the field of anti-interference and secure communication. Background technique [0002] In a communication system that requires security and anti-jamming, it is usually required that the communication signal is not easily detected or intercepted by a third party and is resistant to channel distortion and signal distortion. Therefore, how to design a wireless signal to meet the two needs is very important in this communication system. The existing methods to achieve anti-detection and anti-interception by changing the source signal characteristics at the signal waveform level mainly include spread spectrum (such as frequency hopping) technology, hybrid based on multi-parameter weighted fractional Fourier transform (WFRFT) Carrier modulation and modulation methods that combine the above two technologies, etc. In recent years, the detection and tracking technology for spread spectrum (such as...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L1/00H04L9/00
Inventor 沙学军王焜房宵杰梅林吴玮白旭
Owner HARBIN INST OF TECH
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