Research On Optimization Technology For Positioning Accuracy In Underwater Acoustic Sensor Networks

Underwater target positioning is an indispensable part of underwater sensor network applications.It has been the focus research in the underwater acoustics field at home and abroad,and has broad application prospects in the commercial and military fields.Mobility,sparse deployment and limited energy are the main characteristics of underwater sensor network due to the complexity of the underwater acoustic environment,which brings lots of challenges to the underwater positioning.Therefore,this paper proposes serverals algorithms to corret the ranging error of the acoustic positioning system including sound ray bending correction,rapid synchronization signal detection and propagation delay estimation algorithm.Besides,an anchor node optimization algorithm is proposed to optimize the positioning effect of the underwater sensor network while balancing the positioning performance and energy efficiency.The paper analyzes the acoustic characteristics of the deep-sea and shallow-sea samples using the data published by the National Oceanic Data Center of the United States,and analyzes the sound ray bending phenomenon of acoustic signals in the marine environment propagation process.Besides,the equivalent sound velocity of beacon ranging is calculated through these data,which can be used tot fix the positioning error caused by bending propagation of the sound ray rapidly.In order to resolve the contradiction between the false alarm and missed detection caused by the fixed threshold setting of the synchronous signal receiver,this paper proposes a delay-time estimation algorithm for underwater acoustic positioning based on the fractional Fourier transform.Firstly,the algorithm matches the filtering method and sets the adaptive dynamic threshold to capture the synchronization signal.Secondly,FRFT is used to remove the false alarm signal using the characterstic that signal and nosie will separate at the appropriate order of FRFT;Finally,the delay error is corrected through FRFT spike offset.The simulation results show that compared with the traditional algorithms,the proposed one can alleviate the contradiction between the false alarm and missed detection,and fixe the positioning error caused by delay error rapidly,which improve the performance of positioning system.This paper proposes a node selection algorithm based on particle swarm optimization for node redundancy in underwater acoustic sensor network positioning.The proposed algorithm select appropriate number of sensor nodes to position target considering communication overhead,residual energy of sensor nodes,sensor node's position suspicious degree,sound ray bending and some other factors.In fact,a utility function is designed to calculate a fitness value using these parameters,and the optimal sensor set will be selected through the iteration of particle swarm algorithm,which can locate the target with the highest accuracy.The simulation results show that the algorithm can get a high accuracy positioning results while using an h small amount of calculation and time.It can effectively improve the energy efficiency of sensor nodes and is suitable for underwater acoustic location scenes.