Study On High Speed Underwater Acoustic Communication Techniques

With the development of oceanic exploirure and communication industry, the need to high rate underwater acoustic communication is more and more urgent. The goal to get high-rate and high credibility communication has become a popular research interest in acoustic communication research field. Many study in acoustic communication are made at present many different instances, a lot of techniques have applied, but the study and application of high-speed underwater acoustic communication technique are lagged because of the particularity of underwater acoustic channel. It does not adapt the development of ocean economy and militaryaffairs technique. In order to overcome much co-channel interference and attain reliable high data rate transmission over underwater acoustic channels, OFDM and SC-FDE technology was selected as major research issue.High data rata OFDM underwater system is put forward based on the study of basic theory. Multi-paths disturbances are restrained by matched guard time based on channel characters analysis. Least Square(LS) Algorithm, Least Mean Square (LMS) Algorithm and its improved on Algorithm to get channel estimation in block pilots are studied in different constellation shape of modulated MQAM. These channel estimation algorithms are simulated and studied on the multi-path channel. SC-FDE technique is introduced to Underwater Acoustic Communication, high data rata SC-FDE underwater system is designed based on the study and analysis of SC-FDE- basic theory. Appropriate circle prefix of system is ensured based on characteristic of underwater acoustic channel. Three sequences of adapted to unique word are studied, then emphasize to research the way of inserted pilot, channel estimation algorithms based on pilot, LS and MMSE equalization ways. The estimations algorithms and equalization ways are simulated and verified and compared. The simulation results predicted that the techniques based on OFDM and SC-FDE are provided with the ability of resisted multi-path on Underwater Acoustic Communication. The experiment of UWA communication based on OFDM was carried out in pool of College of Marine Engineering, Northwestern Polytechnical University. It showed that the communication method could perform very well and the influence of multi-path was reduced effectively.