Diversity Techniques Based Blind Equalization Algorithm And Simulation

At present, the report on the research of channel blind equalization processing, which combined the diversity techniques with blind equalization technique, is not so much at home and abroad. But it is a very significant topic to research on channel blind equalization technique by means of diversity techniques and making full use of its characteristic of reducing the fading, and it is also an advanced topic in modern signal processing field. Aiming at the disadvantage of single channel Constant Modulus Algorithm (CMA), the blind equalization theory, algorithm and simulation based on diversity techniques is deep studied in this dissertation. The main contributions are as follows:1. Aiming at the shortcoming of CMA in single channel equalization , Equal Gain Combining Time diversity based Decision Feedback blind Equalization (EGCT-DFE) is proposed on the basis of analyzing time diversity and the performance of decision feedback equalizer. For overcoming CMA not to be sensitive to the phase, Modified CMA (MCMA) is introduced in EGCT-DFE, marked as MEGCT-DFE. Simulation results indicate that the proposed algorithm has more superior performance than single channel CMA.2. Maximal Ratio Combining Spatial diversity based Decision Feedback blind equalization (MRCS-DFE) is proposed on the basis of analyzing spatial diversity and decision feedback equalizer's performance . The proposed algorithm employs spatial diversity for reducing fading effect and utilizes decision feedback equalizer to overcome Inter-Symbol Interference (ISI). So, the proposed algorithm has faster convergence speed and smaller Mean Square Error (MSE).3. CMADFE+DD blind equalization algorithm based on Equal Gain Combining Spatial diversity (EGCS-CMADFE+DD) is proposed by using the respective advantages of CMA and DD. For eliminating the carrier phase or frequency offset introduced by time- varying channel, a spatial diversity based decision feedback blind equalization algorithm with digital phase-locked loop is proposed.4. By analyzing the performance of frequency diversity and selective combining, a Selective Combining Frequency diversity based CMA blind equalization (SCF-CMA)is proposed. Simulation results show that the new algorithm makes more improvement than the single channel blind equalization algorithm. According to the shortcoming of the traditional frequency diversity blind equalizater slow convergence rate and large mean square error, a algorithm called Joint Combining Frequency diversity based CMA blind equalization(JCF-CMA) is proposed by jointing the equal gain combining and selective combining for the the two combining are easy to realize. The Simulation results demonstrate that the JCF-CMA has faster convergence rate and lower MSE than the single combining frequency diversity based CMA blind equalization.