Study On The Key Techniques In High Speed Underwater Acoustic Communication System

With the rapid development of ocean and information technology, the requirement of transmitting the data through the underwater channel is increasing greatly.Nowadays, high data rate communication through the severely band-limited underwater acoustic channel is of general interest in the field of underwater communication.Because of the adverse characteristic of underwater acoustic channel, it becomes a challenge for high data-rate, high reliable information transmission over underwater acoustic channels.The main difficulty to achieve high data rate is the Inter-symbol Interference.To attain reliable high data rate transmission over underwater acoustic channels, QAM technology was selected as major research issue. Adaptive equalization technique was applied to overcome the inter-symbol interference caused by channel multipath propagation.The characteristics of underwater acoustic channel and its effect on underwater acoustic communication were introduced in this thesis.The fading characteristics of underwater acoustic channels were analyzed.The underwater acoustic multipath channel model is established on the basis of ray theory,and parameters of two multipath channels were given. In combination with the characteristics of underwater acoustic channels,systemtic and in-deep study on implementation of QAM and equalization technique were performed.According to the system requirements of medium and short range underwater acoustic communication, an underwater acoustic communication system based on QAM technique was present in this paper, the equalizer applied for medium and short range acoustic channel was designed,and the simulation results were given latter. The simulation results predicted that the medium and short range acoustic communication system which based on QAM technique could satisfaction the requirements of the information transmission system. Considering she requirement of high speed underwater acoustic communication,the orthogonal frequency division multiplexing technique is proposed for high speed underwater acoustic communication,and the feasibility of the orthogonal frequency division multiplexing technique is verified through computer simulation.