Earch On Data Acquisition And Processing Method In Underwater Wireless Sensor Networks

Covering more than 70% of the earth's total area,the ocean is rich in Marine species,rare mineral resources and various types of energy,and plays an important role in the earth's ecosystem and environmental system.Due to the complicated and changeable ocean environment and the high cost of experiments,human beings' understanding of the ocean is still very limited.Many researches are still in the theoretical and simulation stage due to the lack of relevant ocean data,which makes the acquisition and processing of ocean information become extremely important.Compared with the existing methods of ocean information acquisition(manual collection and submarine cable network),using underwater wireless sensor network(UWSNs)to collect ocean information is the mainstream trend of ocean data acquisition in the future.It has the characteristics of flexible deployment and real-time data,and can obtain multi-dimensional information of underwater space and reduce the cost of data acquisition.In recent years,the study of underwater wireless sensor network mainly focuses on network architecture,communication protocol,positioning and navigation,time synchronization and so on.The research of data acquisition by underwater acoustic communication focuses on network architecture design,communication protocol design and data acquisition path planning algorithm.All this has yielded remarkable results.On the contrary,there are relatively few concrete designs and examples about the direction of underwater data acquisition and processing system,especially the application research of remote data acquisition by underwater acoustic communication,which lacks complete and systematic design and implementation.Therefore,the research of underwater wireless sensor network information acquisition and processing system is very necessary.Underwater information from front-end data acquisition to back-end data application,communication technology plays a bridge role in the middle.At present,the communication technology used in underwater wireless sensor network mainly includes three kinds: underwater acoustic communication technology,underwater electromagnetic wave communication technology,underwater optical communication technology.Radio or optical communication has a high transmission rate but a short communication distance.Although underwater acoustic communication has shortcomings such as long delay,low bandwidth and high bit error rate,it is the main way of medium and long distance information transmission.Its communication distance can reach several kilometers or even dozens of kilometers.In the wide area underwater sensor network,underwater acoustic communication has irreplaceable advantages for underwater data acquisition.Therefore,this paper studies an underwater wireless sensor network data acquisition and processing system suitable for underwater acoustic communication,which is equipped with a variety of sensors(conductivity,temperature and depth instrument(CTD),optical camera,digital sonar equipment)and has sensor data acquisition functions.In order to make full use of underwater acoustic channel transmission capability,we investigate the characteristics of underwater acoustic channel transmission and the characteristics of sensor data commonly used in Marine science,and analyze the requirements of different types of data on transmission.In view of the characteristics of CTD data,this paper proposes a high compression rate method based on data context correlation on the basis of traditional text compression method,combining data structure reconstruction and prior CTD data difference range.In view of the characteristics of image data,on the basis of the traditional compression method,this paper proposes the multibatch transmission strategy to make full use of underwater network resources.Meanwhile,the original mean filtering method is improved and the mean filtering with a prior factor is proposed,which has a good effect on the image recovery with missing at the receiving end.In view of the characteristics of sonar data and based on the concept of "Cloud-Ocean Computing",this paper proposes an underwater terminal data image transformation method based on point cloud to complete the transmission of sonar scanning information in the form of images.Finally,the preprocessed data is transmitted to the land shore-based platform through underwater acoustic channel,which improves the efficiency,reliability and stability of underwater sensor data acquisition.The main work of this paper is as follows:(1)We investigate the communication characteristics of underwater acoustic channel,analyze the characteristics of various sensor data(CTD data,image data,sonar data)and the requirements of information acquisition for network transmission.Combined with transmission requirements and underwater acoustic channel characteristics,based on the idea of "Cloud-Ocean Computing",we transfer the data processing process to the underwater front-end and design data processing methods to improve the adaptability of information collection to the network.(2)We design and implement a data acquisition and processing system for underwater wireless sensor network.The system data processing module is Raspberry PI 4 Model B.The information transfer module is an underwater acoustic communication machine.Sensor modules include the CTD,which collects underwater temperature, conductivity,and pressure,and the underwater optical camera, which captures ocean optical images,as well as the single-beam imaging sonar,which collects sonar data.(3)Design and implement the data processing algorithm of the system,Based on the traditional compression method,a high pressure CTD data compression method was proposed by reconstructing THE CTD data structure and combining the prior data change difference range.For image data,we propose a multi-batch transmission strategy and an improved mean filtering method to recover image loss caused by packet loss at the receiving end.For sonar data, point cloud data is converted into image data in underwater terminal, and image data is identified,clipped and marked.These methods can greatly improve the efficiency of underwater data transmission.(4)Based on distributed underwater wireless sensor network(WSN), field test and verification are carried out in real ocean environment.After testing,the data acquisition and processing system designed in this paper can effectively solve the problem of data acquisition in underwater wireless sensor network,and has available functions and robustness.This provides a reference example for obtaining high quality data in the Marine environment.At the same time,we propose an improved method through simulation iteration to further improve the efficiency of underwater wireless sensor network data acquisition and processing.