Research On Sparse Underwater Acoustic Channel Blind Equalization Under Impulsive Noise Environment

Underwater acoustic communication draws attention from countries around the world along with Marine resources exploitation and Marine homeland defense demand. High quality reliable signal reception techniques become a hot spot of underwater acoustic communication research. Adaptive blind equalization technology does not need to send training sequence periodically, which contributes to effectively save the limited underwater acoustic communication bandwidth, improve communication efficiency as well as communication quality. In recent years, studies indicate that environmental noise of underwater acoustic channel shows the property of pulse and high speed underwater acoustic communication channel is characterized by typical sparse. Pulse environment noise and sparse features become the technical bottleneck when blind equalization technology is applied into the underwater acoustic communication. In view of the reality of underwater acoustic channel affected by impulse noise and sparse features, the corresponding improved algorithm is put forward and the simulation is carried out on the basis of a summary of existing research results at home and abroad. Numbers of simulation results on underwater acoustic channel show that all kinds of improved algorithm improve the robustness of the algorithm convergence and have good equalization performance.The main research contents in this paper are:1.The current state of blind equalization and the basic principles of blind equalization are discussed. Constant Modulus Algorithm is summarized. The typical structures of blind equalizer are introduced.2.The model of impulse noise is briefly described in this paper. Normalized p-norm LMS-CMA under impulsive environment and CMA based on nonlinear transformation are concluded. On this basis, three improved algorithms are proposed. The three are SLMS-CMA,DLMS-CMA and CMA based on nonlinear transformation. Both theoretical analyses and simulation results show that these new improved algorithms are more effectively.3.The researches of CMA on sparse underwater acoustic channel are summarized. The main present algorithms are SSP-CMA, TSP-CMA, SSPRLS-CMA, TSPRLS-CMA and TSP-DFE. The validity of the algorithms are proved by simulation results.