Research On Preselection And Blind Equalization Technology For Modulation Recognation Front-end Processing

The complexity of the wireless communication environment has brought great challenges to a non-cooperative communication, the received signals are aliased which is harmful to filter out a signal having a specific spectral characteristic from the received signal. wireless fading channel cause inter symbol interference of the signal, so that the distorted received signal make the received signal processing more difficult. Signal’s preselection and blind equalization technology is two key technologies to accurate modulation recognition and parameter estimation in a wireless fading channel environment.This paper focuses on the typical digital modulation signal recognition preselection technology, including: modulation recognition preselection system design and channel blind equalization system design, the overall demand for the system to be analyzed, We introduce algorithm theory and simulation analysis about the preselection module and channel blind equalization technology.The main contents of the thesis is mainly reflected in the following sections:Firstly, We designed the preselection system scheme on modulation recognition. We design the preselection system solutions, filter out the signal that we are interested from the received signal and send to the modulation recognition system for subsequent processing and recognition. We completed a blind equalization system design and used blind equalization removing the effects of fading and multipath effects from the signal that we are interested.Secondly, We designed the signal’s pre-processing module, proposed reasonable process flow, and the key algorithms of the processes are described and simulated. The Welch periodogram algorithm and FCME algorithm combined periodogram FCME bandwidth estimation algorithm which can estimate signal bandwidth with higher accuracy. We introduced the basic principle of signal parameter estimation, calculation method, simulated and analyzed the signal parameter estimation algorithm under different conditions. Signal characteristics are used to filter the signals.Finally, the currently popular Bussgang blind equalization algorithm is studied. Based on the theoretical analysis, simulated and analyzed constant modulus algorithm and modified constant modulus algorithm for constant modulus signal and amplitude and phase modulation signal’s equalization performance with residual inter symbol interference and bit error rate in fading channel conditions.