Research On Channel Estimation And Equalization Technologies Of OFDM In UWA Communication

The purpose of the underwater acoustic communication system lies in dependablely transmiting the signal from the source to the end through ocean acoustic channel at high speed. OFDM (Orthogonal Frequency Division Multiplexing) is a method that can combat multipaths, fully use the fequency band and has high data rate , and has a promising future in UWA communication. While longer the transmission range, worse the underwater conditions with multipaths and Doppler offset, which needs to design the system parameters and take practical methods to improve the system. Channel estimation and equalization are the key technologies in communication transmission field. They directly affect the performance of the communication system.This paper mainly focuses on the channel estimation and equalization technologies of OFDM in UWA communication. Firstly,the basic model and express form are introduced, also the necessity of channel estimation and equalization in OFDM UWA communication is discussed. This paper mainly disscuss the channel estimation based on pilot symbol assisted modulation, research on Block,Comb and Club pilot pattern and simulate three pilot patterns combining UWA communication channel condition. About the Block pilot pattern problem, investigate and simulate LS,MMSE and LMMSE algorithms. About the Comb and Club pilot pattern problem, kinds of schemes based on pilot are proposed,such as nearest interpolation, linearity interpolation, ChoiSI interpolation and Spline interpolation, and some simulations are completed. About LS algorithm problem,noise reduction based on wavelet transform and channel estimation based on DFT algorithm are given,and some simulations are completed. At last, Do experimentation in pool, different channel estimation and equalization algorithms are proved.