Four-weighted fractional Fourier transform-based narrowband interference suppression method

A fractional Fourier, narrow-band interference technology, applied in baseband system components, shaping network in transmitter/receiver, multi-frequency code system, etc., to achieve the effect of minimum mean square error reduction

Active Publication Date: 2012-08-01
HARBIN INST OF TECH
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Problems solved by technology

[0003] The purpose of the present invention is to provide a method for narrowband interference suppression based on four-term weighted fractional Fourier transform, to solve the problem that the existing narrowband suppression technology cannot directly carry out narrowband interference suppression on the fractional domain

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  • Four-weighted fractional Fourier transform-based narrowband interference suppression method
  • Four-weighted fractional Fourier transform-based narrowband interference suppression method
  • Four-weighted fractional Fourier transform-based narrowband interference suppression method

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specific Embodiment approach 1

[0029] Specific implementation mode one: as Figure 1~2 As shown, the specific process of the narrowband interference suppression method based on the four-item weighted fractional Fourier transform described in this embodiment is:

[0030] Step 1, α-order 4-WFRFT transformation: For a digital signal with a length of N (X 0 ={x 1 , x 2 ,...,x N}), carry out α-order 4-WFRFT transformation, and transform to fractional domain signal S={s 1 ,s 2 ,...s N}, where s i Represents the i-th fractional domain sampling point signal; for the convenience of description, here we assume that X 1 =(y 1 ,y 2 ,...,y N ) for X 0 The signal after a Fourier transform, by the nature of the Fourier transform, X 1 Signal X after Fourier transform 2 =(x N , x N-1 ,...,x 1 ), also by the property of Fourier transform, X 2 Signal X after Fourier transform 3 =(y N ,y N-1 ,...,y 1 );

[0031] Step 2. Determine the position of the strong interference point:

[0032] Set the position of...

Embodiment

[0063] figure 1 is a schematic diagram of the principle of the present invention, the length of the signal is N, the sampling point i is a point subject to strong interference, and the present invention replaces the sampling point i with the coefficient of the sampling point N-i+1, figure 2 It is the realization step of the principle of the present invention, based on figure 2 Examples are as follows:

[0064] The signal to be detected is assumed to be a triangular wave signal X, and the sampling period is 0.1. The signal in the transform domain is set to S, the position of the disturbed sampling point is 45, the interference amplitude is 10, and the transform order α=0.6;

[0065] 1. Perform 4-WFRFT transformation on digital signal X with signal length N=101, and transform it into fractional domain signal S;

[0066] 2. Estimate the point of strong interference. According to known conditions, the sampling point of interference is i=45;

[0067] Third, using the coeffic...

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Abstract

The invention discloses a four-weighted fractional Fourier transform (WFRFT)-based narrowband interference suppression method, relates to an interference suppression method for a communication system, and aims to solve the problem that direct narrowband interference suppression cannot be realized in a fractional domain by the conventional narrowband interference suppression technology. The method mainly comprises the following steps of: performing alpha-order WFRFT; determining the position of a strong interference point; performing coefficient replacement; multiplying a signal point of an (N-i+1)th point before the transform by using a corresponding weighting coefficient to obtain si, performing certain transform on the conventional weighting coefficients A=[A0, A1, A2, A3] to obtain corresponding weighting coefficients, substituting a product of matrixes H and A to obtain a corresponding weighting coefficient A'=(HA<H>)<H>=AH, and multiplying the weighting coefficient A' by using a weighted function of an ith point to obtain a product which is used as a new point of the fractional domain to replace the strong interference point, wherein the whole process of transformation coefficient replacement is expressed by a formula si=AH[A<H>(AA<H><-1>SN-i+1]; and performing -alpha-order 4-WFRFT. The method is used for the narrowband interference suppression in the fractional domain.

Description

technical field [0001] The invention relates to an interference suppression method of a communication system, in particular to a narrow-band suppression method based on four-item weighted fractional Fourier transform. Background technique [0002] Narrowband interference is a problem often encountered in practical communication systems, and effective narrowband interference suppression methods can improve the performance of broadband communication systems. Existing narrowband suppression techniques are divided into time-domain suppression, transform-domain suppression and code-assisted suppression. The time-domain NBI suppression technology mainly uses the strong correlation of the narrowband signal and the non-strong correlation of the wideband signal to suppress, and its anti-interference performance can achieve the best, so it has been paid attention to by people and has been widely studied. Time-domain suppression technology is simple to implement, and the optimal weigh...

Claims

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Application Information

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IPC IPC(8): H04L25/03H04L27/26
Inventor 沙学军李勇梅林吴宣利房宵杰邱昕吴玮
Owner HARBIN INST OF TECH
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