Research On High-speed Underwater Acoustic Communication Based On Filter Bank Multicarrier

Underwater acoustic communication technology is a necessary technology for underwater data transmission,and play a very important role in military and civilian areas.With the development of science and technology,the traditional low speed and low reliability communication is hard to meet the military and civilian needs.Underwater acoustic communication technology is developing towards high speed and high reliability.Filter bank multicarrier(FBMC)technology belongs to the category of generalized frequency division multiplexing(GFDM).It introduces a prototype pulse with good performance,which makes the system have the characteristics of against the inter symbol interference(ISI)and inter carrier interference(ICI).Meanwhile,FBMC does not need to add cyclic prefix(CP),which further improves the communication rate and the spectrum efficiency.However,there are some problems with FBMC.First,the introduction of prototype pulse is based on the relaxation of orthogonal condition.FBMC only keeps orthogonal in real number domain,and the complex number domain does not satisfy,which means that modulation and demodulation cannot be as simple and complicated as OFDM.Secondly,the nature of real number domain orthogonality will introduce intrinsic imaginary interference to symbols and subcarriers,which brings great trouble to channel estimation and channel equalization.In view of the above problems,this paper combines the characteristics of underwater acoustic channel,then studies some problems existing in FBMC system,and gives corresponding solutions and improvement methods.(1)The characteristics of the underwater acoustic channel determine the performance of the whole communication system.So first of all,the paper studies how these characteristics affect the communication system from the physical characteristics and expansion characteristics of the underwater acoustic channel,which lays the foundation for the research on the prototype pulse design and the robust receiving technology.(2)In view of the complexity of the traditional FBMC system,two different forms of rapid implementation are studied.The detailed derivation process is given,which reduces the amount of calculation and makes the system more practical.In prototype pulse design,the performance of prototype pulse is analyzed through time domain,frequency domain and ambiguity function.Finally,based on the pulse time-frequency analysis results and the underwater acoustic channel expansion theory,a prototype pulse design method based on underwater acoustic propagation characteristics is presented.(3)Aiming at the influence of underwater acoustic channel on communication system,the robust receiver technology of communication receiver is studied.The first is the estimation and compensation of Doppler shift.The conventional data packet length measurement method and variable sampling compensation method are adopted.Then,on the channel estimation,a method based on the approximation of interference is used,and three different pilot structures are given,and the corresponding simulation analysis is carried out.Finally,the channel equalization is used to apply the time reversal mirror algorithm to the underwater acoustic FBMC system.Two different time reversal algorithms are studied,and their performance is analyzed through simulation and comparison.(4)In view of the theoretical research of this paper,a complete underwater acoustic FBMC field experiment is given,which mainly validates the implementation of FBMC,the performance of the prototype pulse and the equalization of time reversal channel.The results of data processing and analysis show that the underwater acoustic communication system based on FBMC has good anti-jamming performance and practical application prospects.