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An Iterative Frequency-Domain Minimum Mean Square Error Equalization Method Based on Weighted Fractional Fourier Transform for Double Dispersion Channels

A minimum mean square error, dual dispersion channel technology, applied to equalizers and other directions, can solve problems such as signal energy dispersion

Active Publication Date: 2016-03-16
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The present invention is to solve the problem of the energy dispersion of the signal in the time domain and the frequency domain at the same time due to the inevitable introduction of multipath transmission and Doppler frequency shift when the signal goes through the channel, and provides a method based on Iterative frequency-domain minimum mean square error equalization method for double-diffused channels with weighted fractional Fourier transform

Method used

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  • An Iterative Frequency-Domain Minimum Mean Square Error Equalization Method Based on Weighted Fractional Fourier Transform for Double Dispersion Channels
  • An Iterative Frequency-Domain Minimum Mean Square Error Equalization Method Based on Weighted Fractional Fourier Transform for Double Dispersion Channels
  • An Iterative Frequency-Domain Minimum Mean Square Error Equalization Method Based on Weighted Fractional Fourier Transform for Double Dispersion Channels

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specific Embodiment approach 1

[0056] Specific implementation mode 1: The iterative frequency-domain minimum mean square error equalization method under the weighted fractional Fourier transform-based double dispersion channel of this implementation mode is implemented in the following steps:

[0057] 1. The sending end of the mixed carrier modulation system completes the mixed carrier modulation to obtain the time domain sequence x;

[0058] 2. Add a cyclic prefix to the time-domain sequence x obtained in step 1 and obtain a time-domain sampling sequence after parallel-to-serial conversion

[0059] 3. The time-domain sampling sequence in step 2 Serial transmission, after going through double dispersive channels, arrives at the receiving end of the mixed carrier modulation system;

[0060] 4. The receiving end of the hybrid carrier modulation system ignores the CP part, and each received time-domain sampling sequence y can be expressed as the convolution form of the sequence at the sending end of the hy...

specific Embodiment approach 2

[0119] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that in step 1, the sending end of the hybrid carrier modulation system completes the hybrid carrier modulation to obtain the time domain sequence x, which is specifically:

[0120] At the sending end, the data bit sequence b with a length of NQ is mapped to an N-long QAM symbol sequence s after constellation modulation, and each Q bit {b n，0 ,...,b n，Q-1} is mapped to a symbol s n , perform -α-order WFRFT on the obtained QAM symbol sequence, and complete the mixed carrier modulation to obtain the time domain sequence:

[0121] x=F -α s=(w 0 I+w 1 F+w 2 A+w 3 f -1 )s

[0122] where F -α Represents -α-order normalized WFRFT matrix; I represents N×N identity matrix; F represents normalized discrete Fourier transform (discreteFouriertransform, DFT) matrix; A represents an N×N permutation matrix, whose internal elements satisfy when when [A] n，m :=δ( N ) In addition, for ...

specific Embodiment approach 3

[0125] Specific embodiment three: the difference between this embodiment and specific embodiment one or two is that in step six, the receiving end of the hybrid carrier modulation system performs a sampling point on the frequency corresponding to a certain subcarrier in the frequency domain received The linear MMSE estimation is specifically:

[0126] u ^ k = u ‾ k + g k H ( y k - H k u ‾ ) ,

[0127] where y k =[y k-D ,...,y k+D ] t , H k contains H df The k-D to k+D lines of the equalizer coefficient vector can be expressed as:

[0128] g k ...

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Abstract

The invention discloses an iteration frequency domain minimum mean square error equilibrium method under a double-dispersion channel based on weighted score Fourier transformation, and relates to an iteration frequency domain minimum mean square error channel equilibrium method in a mixed carrier wave communication system under a wireless double-dispersion channel or an underwater acoustic susceptance channel, in order to solve the problem of energy dispersion of signals on a time domain or a frequency domain at the same time. The method comprises the following steps that: firstly, a mixed carrier wave modulation system emitting end completes the mixed carrier wave modulation; secondly, a cyclic prefix is added for a time domain sequence x and is subjected to parallel-serial conversion; thirdly, a time domain sampling sequence is transmitted in serial; fourthly, the mixed carrier wave modulation system receiving end neglects a CP (computer program) part; fifthly, the time domain sampling sequence y is subjected to DFT (discrete Fourier transformation) at N points; sixthly, sampling points at the frequency corresponding to a certain sub carrier wave of the frequency domain are subjected to linear MMSE (minimum mean square error) estimation and N-point-stage WFRFT (weighted score Fourier transformation); seventhly, apriori information and Rho s=X(s, s) are estimated gradually; eighthly, the apriori information of the corresponding frequency domain is calculated; ninthly, the apriori information is fed back. The iteration frequency domain minimum mean square error equilibrium method under the double-dispersion channel based on weighted score Fourier transformation provided by the invention is applied to the mobile communication field.

Description

technical field [0001] The invention relates to an iterative frequency-domain minimum mean square error channel equalization method in a mixed carrier communication system under a wireless double-dispersion channel or an underwater sonar channel. Background technique [0002] With the development of land transportation, aerospace and submarine communication technologies, the channel environment experienced by communication systems is further complicated. Due to the Doppler frequency shift caused by the high-speed relative movement of the communication parties, a signal detection system for the future LTE system based on Orthogonal Frequency Division Multiplexing (OFDM) and single carrier (single carrier, SC) modulation is proposed. challenge. Especially in communication environments such as high-speed rail, low-altitude aircraft, low-elevation satellites, and underwater sonar, the signal inevitably introduces multipath transmission and Doppler frequency shift when it passes...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/01
Inventor 沙学军王焜吴玮陈平白旭
Owner HARBIN INST OF TECH
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