Design And Implementation Of Mobile Underwater Acoustic Single Carrier Frequency Domain Equalization System

With the development of underwater acoustic communication technology,the research on high-speed underwater acoustic communication has become the target to researchers.Single Carrier Frequency Domain Equalization Technology and Orthogonal Frequency Division Multiplexing Technology belong to high-speed communication technology and they both have excellent performance in resisting multipath delay.However,OFDM technology has the disadvantages of high peak-to-average ratio and sensitivity to carrier frequency offset,while Single Carrier Frequency Domain Equalization technology does not.In view of this,this paper mainly studies the application of Single Carrier Frequency Domain Equalization technology in high-speed underwater acoustic communication system.In this paper,a Single Carrier Frequency Domain Equalized underwater acoustic communication system for mobile platform is designed.Firstly,this paper introduces the research status of Single Carrier Frequency Domain Equalization technology in radio and underwater acoustic fields,then the characteristics of underwater acoustic channel and the channel model applied in this paper are introduced,based on the study of SC-FDE principle and system transmission block diagram,a SC-FDE underwater acoustic communication transmission system is established.In the launching system,the frame structure is designed reasonably,the training sequence is selected and the system parameters are set.In the receiving system,coarse synchronization and fine synchronization,doppler estimation and compensation,channel estimation and frequency equalization are accomplished.Considering the influence of doppler effect in underwater acoustic communication,a doppler factor estimation method based on training sequence is designed to estimate the doppler effect effectively.The bit error rate performance curves of the system under forced zero equalization,minimum mean square error equalization and noise prediction decision feedback equalization are obtained by simulation.Then,the mature simulation algorithm is transplanted to DSP platform TMS320C6748 for implementation,the related driver design and algorithm writing work are introduced,the modulation process and demodulation process are introduced in turn.After the demodulation algorithm is realized,the time of each step is tested to ensure the real-time performance of the system.Finally,the underwater acoustic communication system based on DSP processor is realized.At last,an experiment carried out in the laboratory and water pool is introduced,The experiment in the channel pool of Harbin Engineering University shows that the system has good ability to resist multipath noise channel and doppler effect.