Efficient Transmission And Target Location Of Underwater Acoustic Monitoring Network

In order to solve the problems of long frame arrival delay and low target estimation accuracy,based on frame structure,this theses defined frame transfer efficiency,analyzed methods to improve the transmission efficiency of each layer of underwater acoustic network,sorted out the methods to improve the transmission efficiency,determined the research contents about channel blind equalization,frame synchronization monitoring and optimal frame length in ARQ to improve transmission efficiency,established the double error model of target location and derived the weighted least squares algorithm to improve the positioning accuracy.The innovation points of this theses are as follows:1.The transmission efficiency of underwater acoustic monitoring network is defined.The research contents about improving transmission efficiency and the accuracy of target estimation are sorted out based on existing work.2.A blind Turbo equalization method for underwater acoustic sparse channel based on Bernoulli prior distribution is proposed.A cascade structure of convolutional encoding and differential encoding in series and a corresponding blind Turbo equalization structure are designed to solve the problem of phase ambiguity in blind Turbo equalization.Bernoulli prior distribution is used to characterize the structure of the underwater acoustic sparse channel.Blind Turbo equalization and channel decoding in the underwater acoustic sparse channel are realized by using Gibbs sampling method under the bayesian mathematical framework.Simulation results show that the proposed method can greatly improve the performance of blind Turbo equalization bit error rate in underwater acoustic sparse channel.3.A scale changing combined filter is proposed as a receiver filter.The combined filter is composed of the sum of different time spreading signals and shifted signals.Based on the theory of matched filtering,the doppler expansion scale,time shifting,and the order of the combined filter are derived for each component of the combined filter,so as to improve the matching degree between the filter and the wideband doppler echo signals with different speeds.The synchronous detection probability and time estimation accuracy with mobile communication are improved.The analytic expression of the doppler factor is derived when the order of fractional Fourier transform is fixed.A joint receiver suitable for underwater acoustic mobile communication is designed,which can detect and estimate parameters simultaneously.4.In order to maximize the channel utilization and optimize the energy consumption per unit bit,the optimal data frame length analytic expression of the underwater acoustic network is derived respectively,which improves the transmission efficiency of the selective repeat ARQ protocol in the underwater acoustic monitoring network.5.A TDOA target location model with double error is constructed.And for this model,a solution algorithm based on weighted global least square method(WTLS)is proposed,and the expression of covariance matrix is derived and the method of determining weights is given.The constrained optimization model is established,and the iterative expression is derived based on Lagrange multiplier method.The solution steps are finally given.The target positioning accuracy of underwater acoustic monitoring network is improved.