Shallow Sea Environment Underwater Acoustic Channel Tracking And Passive Time Reversal Mirror

Underwater acoustic communication for ocean communication often has strong delay-Doppler double spread characteristics,which shows that underwater acoustic channels have obvious multipath effects and Doppler effects,and are fast time-varyin g.At present,for ocean channel communication systems,the method of obtaining underwater acoustic channel state information has been developed from channel estimation to channel tracking.Common channel tracking me thods can only roughly restore the overall state information of the channel,and cannot obtain specific information about the sub-path of the channel.In addition,the time-varyin g marine environment and double diffusion characteristics a lso lim it the trackin g performance of this method.Whether it can successfully track the status of different paths in the ocean will affect the capabilities of the ocean communication and information processing system.In this paper,a multi-Bernoulli filter(MBF)based on a random finite set is selected as the marine environment tracker,and its s tate model is optimized so that the tracker can adaptive ly determine the positive Doppler factor.Ne gative,better tracking performance when the environment matches the model.At the same time,the MB filter is a path-specific channel tracker,this can assist us in obtaining channel-specific channel information on the temporal changes of the marine environment.Different from common multi-target tracking,the measurement of sub-paths in underwater acoustic channel track ing cannot be directly obtained.The traditional channel estima tion can only estima te the channel impulse response,so this artic le considers combinin g the channel es tima tion with the peak search method to obtain the sub-path measurement value required by the tracker.Finally,simulation and experimental data are used to verify the accuracy of the tracker and the measurement method obtained.Using the time-varyin g path parameters of the underwater acoustic channel obtained by the above-mentioned channel tracker,this paper proposes a passive time reversal mirror a lgorithm for the dual-spread channel for the de lay-Doppler dual-spread channel.The traditional time-reversal m irror receiver only compensates for an average Doppler factor for multipath,and is not suitable for the delay-Doppler dual-spread UWA communication system.In this paper,the above-mentioned sub-path underwater acoustic channel tracker can be used to realize the time delay and Doppler factor compensation specific to each path,so that the improved time reversal m irror me thod for the dual spread channel can effectively focus the multipath energy.This improves the performance of the receiver.The simulation and Qiandao Lake experiment results show that the Do Bernoulli tracker,wh ich combines the physical characteris tics of the underwater acoustic channel to optimize the state model,can effectively track the time-varyin g underwater acoustic multi-path channel in the shallow sea and obtain the delay of the sub-path channel.And Doppler factor parameters.Compared with conventional channel trackin g methods,the tracker can track channel s tate information more accurately.At the same time,the improved time reversal mirror algorithm based on channel tracking effectively reduces the demodulation error of the underwater acoustic communication system.The communication experiment results in the multipath time-varyin g underwater acoustic channel show that the channel trackin g method based on the multi-Bernoulli filte r and the improved time reversa l mirror based on this method significantly improve the transmission of the underwater acoustic communication system performance.