Research On The Equalization Technology Of Underwater Acoustic Communication Based On Filter Bank Multicarrier

In recent years,our society and economy have developed vigorously.The requirement of transmission quality and rate of underwater acoustic communication is getting higher and higher.Filter Bank Multi-carrier underwater acoustic communication is a communication method based on multi-carrier transmission.This method has many advantages,such as anti-ISI,anti-Doppler frequency shift and high bandwidth utilization.Therefore,this communication mode has become a hotspot in the field of high-speed underwater acoustic communication.Due to the influence of acoustic characteristics,transmission attenuation and other factors,the underwater acoustic channel has a greater impact on data symbols.Although the FBMC communication system adopts the multi-carrier transmission mode,it can't avoid the interference caused by the above factors.In order to compensate for the distortion of data symbols at the receiving end,the application of channel equalization technology is particularly important.Aiming at the above problems,this paper takes underwater acoustic FBMC communication system as a platform to study the application of equalization technology to improve the bit error rate of the signal at the receiving end of the system.The research contents mainly include the following points:(1)The basic principle and key technology of filter bank multicarrier communication system are studied.It mainly includes prototype pulse filter technology and offset quadrature amplitude modulation technology.This paper also introduces the framework of the whole communication system and two ways of fast implementation;(2)The characteristics model of underwater acoustic channel is studied.This paper introduces several main factors of interference of underwater acoustic channel to communication system: multipath effect,environmental noise,transmission loss and Doppler frequency shift.At the same time,the paper introduces the traditional equalization method and algorithm principle,which lays the foundation for the later research on the equalization method suitable for the communication system in this paper.(3)The principle of the combination of passive time reversal and adaptive decision feedback,the combination of passive time reversal and bidirectional decision feedback is studied.The process and signal structure of the receiver are given in this paper.The equalization effect of the above two equalization methods is verified by simulation channel and measured underwater acoustic channel.The results show that the above two balancing methods have good results;(4)The principle of the joint equalization method of virtual time reversal and adaptive decision feedback is studied.The algorithm of channel estimation for virtual time reversal,the exponential window recursive least squares algorithm based on 0-norm constrained dichotomous coordinate descent method,is presented.It is verified by simulation channel and measured underwater acoustic channel.The results show that the proposed channel estimation algorithm can accurately estimate the channel delay information,and after virtual time reversal and adaptive decision feedback equalization,good error rate performance is achieved.