A Modified Mode-Decision Multi-mode Blind Equalization Method

Abstract

The invention discloses a modified mode decision multi-mode blind equalization method MMDMMA, which redefines the cost function, and obtains the weight vector update formula of the forward equalizer and the feedback filter according to the stochastic gradient descent method from the defined cost function; using The leakage factor with time-varying characteristics replaces the fixed decision factor of the existing mode-decision multi-mode blind equalization method MDMMA, and can accurately track time-varying signals. The effect of this substitution is: before convergence, the decision error is large, the time-varying leakage factor is also large, and the convergence speed is fast; after convergence, the decision error is small, the time-varying leakage factor is also small, and the convergence speed is slow; using time-varying leakage The factor avoids the divergence of the blind equalization process of the MDMMA method and avoids misadjustment. The method of the invention has small mean square error, fast convergence speed, strong capability of suppressing intersymbol interference and correcting phase rotation, and has obvious improvement compared with the mode judgment multimode blind equalization method MDMMA and the normal mode blind equalization method CMA.

Description

technical field [0001] The invention belongs to the technical field of satellite communication, and in particular relates to an improved judgment multi-mode blind equalization method. Background technique [0002] In the mobile satellite communication system, intersymbol interference (ISI) and phase deflection caused by multipath fading and Doppler effect cause severe distortion of the transmitted signal and distortion at the receiving end, seriously affecting the communication quality. In order to improve the communication quality, the researchers proposed a blind equalization method CMA based on data reliability decision guidance. This type of method mainly uses the forward equalizer to eliminate the leading distortion of channel equalization, and uses the feedback filter to cancel the tail distortion. However, as modern communication technology requires higher and higher power utilization of modulated signals, high-order amplitude modulation signal QAM is often used to im...

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Problems solved by technology

[0016] In view of the constellation characteristics of high-order QAM signals and the defect that the fixed decision factor in the existing mode-decision multi-mode blind equalization method MDMMA does not have dynamic tracking performance, the present invention discloses a modified mode-decision multi-mode blind equalization method MMDMMA, through Define a new cost function and replace the fixed decision factor in the existing MDMMA technology with the defined time-varying leakage factor, which effectively improves the mode decision multi-mode blind equalization method MDMMA in suppressing intersymbol interference ISI, correcting phase deflection, reducing steady-state error, etc. aspects of performance

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