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

A minimum mean square error, fractional Fourier technology, used in baseband system components, shaping networks in transmitter/receiver, multi-frequency code systems, etc., can solve problems such as signal energy dispersion

Active Publication Date: 2016-07-06
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 due to the large Doppler frequency shift caused by the high-speed relative movement of the communication parties, and provides a dual-dispersion channel based on weighted fractional Fourier transform. Iterative time-domain minimum mean square error equalization method

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

[0062] Specific implementation mode 1: The iterative time-domain minimum mean square error equalization method under the weighted fractional Fourier transform-based dual dispersion channel of this implementation mode is implemented in the following steps:

[0063] 1. The sending end of the mixed carrier modulation system completes the mixed carrier modulation to obtain the time domain sequence x;

[0064] 2. Add a cyclic prefix to the time-domain sequence x obtained in step 1 and obtain a time-domain sampling sequence y after parallel-to-serial conversion;

[0065] 3. Send the time-domain sampling sequence y obtained in step 2 serially, sample the received time-domain signal, remove the CP and perform serial-to-parallel conversion processing at the receiving end of the double dispersion channel, and then obtain the channel coefficient by means of the channel estimation method;

[0066] 4. The receiving end samples the received time-domain signal and performs linear MMSE estima...

specific Embodiment approach 2

[0121] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that in step 1, the sending end of the mixed carrier modulation system completes the mixed carrier modulation to obtain the time domain sequence x. The specific process is as follows:

[0122] At the sending end of the hybrid carrier modulation system, the data bit sequence b of length NQ is mapped to an N-length QAM symbol sequence s through constellation modulation, and each Q bit {b n，0 ,...,b n，Q-1} is mapped to a symbol s n , perform -α-order weighted fractional Fourier transform on the obtained QAM symbol sequence, and complete the mixed carrier modulation to obtain the time domain sequence x:

[0123] x=F -α s=(w 0 I+w 1 F+w 2 A+w 3 f -1 )s(1)

[0124] where F -α Represents the -α-order normalized weighted fractional Fourier transform matrix, I represents the N×N identity matrix, F represents the normalized discrete Fourier transform matrix, A represents an N×N per...

specific Embodiment approach 3

[0128] Embodiment 3: The difference between this embodiment and Embodiment 1 or 2 is that in step 4, the receiver samples and estimates the received time-domain signal as follows:

[0129] Time-domain signal sampling: add a cyclic prefix to the time-domain sequence x modulated by the mixed carrier and obtain a time-domain sampling sequence after parallel-to-serial conversion, send the obtained time-domain sampling sequence serially, and reach the receiving end after going through a double-diffusion channel, ignoring In the CP part, each time-domain sampling sequence received by the receiving end is expressed as the convolution form of the sending end sequence and the discrete impulse response of the channel:

[0130] y m = Σ l = 0 N h - 1 h ...

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Abstract

An iteration time domain MMSE (minimum mean square error) equilibrium method based on weighted-type fractional Fourier transform (WFRFT) in a doubly dispersive channel is provided. The invention relates to an iteration time domain MMSE equilibrium method in a hybrid carrier communication system. The method aims at solving a problem of simultaneous energy dispersion in tune domain and frequency domain by signals, which is caused by large Doppler frequency shift due to high-speed relative motion of two parties in the communications. The method comprises the following steps that 1) a time domain x is obtained through the completion of hybrid carrier modulation; 2) a time domain sampling sequence y is obtained; 3) the time domain sampling sequence y is transmitted serially and channel coefficients are obtained; 4) received time domain signals are sampled, and linear MMSE estimations are conducted on the time domain signals; 5) a time domain estimation sequence after linear MMSE estimations are converted to an alpha-order EFRFT domain through an N-point alpha-order WFRFT; 6) statistical mean value and square error of every symbol in the alpha-order WFRFT domain estimated value sequence are respectively calculated by using an array R (1) and an array C (1) obtained in step 5); 7) a priori information in the next iteration is calculated. The method can be applied to the field of mobile communications.

Description

technical field [0001] The invention relates to an iterative time-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, aviation, aerospace and underwater communication technology, the channel environment experienced by the communication system is further complicated. The Doppler frequency shift caused by the high-speed relative movement of the communication parties poses a challenge to the signal detection system of the LTE system based on orthogonal frequency division multiplexing (OFDM) and single carrier (single carrier, SC) modulation . 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 through...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L25/03H04L27/26
Inventor 沙学军王焜吴玮李勇房宵杰李月
Owner HARBIN INST OF TECH
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