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Signal modulation method based on weighted-type fractional Fourier transform and energy spreading transform

A fractional Fourier and energy expansion technology, applied in the field of signal modulation based on weighted fractional Fourier transform and energy expansion transform, can solve problems such as poor anti-interception effect

Active Publication Date: 2013-12-11
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-type fractional Fourier transform and energy spreading transform
  • Signal modulation method based on weighted-type fractional Fourier transform and energy spreading transform
  • Signal modulation method based on weighted-type fractional Fourier transform and energy spreading transform

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specific Embodiment approach 1

[0031] Specific Embodiment 1: The signal modulation method based on weighted fractional Fourier transform and energy expansion transform in this embodiment includes:

[0032] 1. Construct an energy expansion transformation matrix, and perform an energy expansion transformation on a source information symbol sequence s with a length of N;

[0033] 2. The transmitting end completes the energy expansion transformation modulation of the source information symbol sequence s through the multi-stage serial weighted fractional Fourier transform and pseudo-random interleaving process, and obtains the modulated sequence x;

[0034] 3. The modulated sequence x is processed by channel cancellation technology to obtain the signal y to be demodulated, and the signal receiving end performs energy expansion and inverse transformation on the demodulated signal y to realize the estimated value of the source information sequence recovered during the demodulation process

[0035] working princi...

specific Embodiment approach 2

[0050] Specific embodiment 2: the difference between this embodiment and specific embodiment 1 is that in the step 1, performing energy expansion transformation on an information sequence s with a length of N is specifically:

[0051] According to the principle of energy expansion transformation, the energy expansion transformation for a certain length N information sequence s can be expressed as:

[0052] x=Es=P μ u μ P μ-1 u μ-1 …P 1 u 1 s, (7)

[0053] where E=P μ u μ …P 1 u 1 Represents the energy expansion transformation matrix, P l (l=1,...,μ) represents a pseudo-random permutation matrix, U l Represents a normalized orthogonal matrix;

[0054] Based on the construction principle of the traditional energy expansion transformation matrix, the normalized orthogonal matrix of each level in the formula (1) is divided into different orders α l The weighted fractional Fourier transform matrix of Instead, a new energy-expanding transformation matrix is ​​construc...

specific Embodiment approach 3

[0057] Specific implementation mode three: the difference between this implementation mode and specific implementation mode one or two is that: the energy spreading transformation modulation of the source information symbol sequence in the step two is specifically:

[0058] (1) First, do α on the source information symbol sequence s 1 order WFRFT;

[0059] (2) Then for the obtained sequence according to the pseudo-random permutation matrix P 1 Do random interleaving;

[0060] (3) Do the second level of α on the interleaved sequence 2 Order WFRFT, according to the obtained sequence according to the pseudo-random permutation matrix P 2 Do random interleaving processing; and so on, until the μth level of WFRFT and interleaving processing is completed, the modulated sequence x is obtained; wherein the transformation order of each level of WFRFT α l (1≤l≤μ) and the structure of the pseudo-random interleaver is controlled by the sending end to change regularly with time.

[006...

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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 in the fields of anti-interference and secret communication. Background technique [0002] In a communication system that requires confidentiality and anti-interference, it is usually required that the communication signal is not easy to be detected or intercepted by a third party, and at the same time be resistant to channel distortion and signal distortion. Therefore, how to design a wireless signal that meets the two requirements is very important in this communication system. Existing methods to achieve anti-detection and anti-interception by changing the characteristics of the source signal at the signal waveform level mainly include spread spectrum (such as frequency hopping) technology, based on multi-parameter weighted-type fractional Fourier transform (WFRFT) Mixed carrier modulation and modulation methods combining the above two technologies, etc. In recent years, detection and tra...

Claims

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Application Information

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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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