Design Of A Multi-dimensional High-order Underwater Acoustic High-speed Communication System

With the enhancement of China's comprehensive national strength and the complex changes in the international situation,the task of developing the ocean cause has become increasingly important and urgent.Ocean issues have become a strategic issue for national development,which has made China's requirements for underwater wireless communications increasingly higher.However,the current underwater acoustic communication system has a large delay and a slow rate,and the frame stuck phenomenon will occur in the transmission of image and video format signals.Therefore,we have proposed a high-order multidimensional 3d OFDM underwater acoustic high-speed communication system to solve the current problems of low modulation rate,small data capacity and high bit error rate in underwater acoustic communication systems.In this thesis,the pulse signal modulation technology,OFDM system and peak-topeak ratio-ratio technology are researched at the forefront,and a high-speed underwater acoustic communication system with medium and long distance,high information transmission rate and low bit error rate is realized.The detailed work of this thesis is as follows:First,we have proposed a multi-dimensional constellation point mapping method based on the MPPAM signal,which maps the pulse position combination and pulse amplitude information of the MPPAM signal to spatial coordinates,increasing the Euclidean distance between the signals,and solving the problem of the low resolution when the MPPAM signal using sound waves as a carrier.Second,we have proposed three characteristics that take pulse amplitude,pulse position,and frequency as information,and improves the OFDM system into a 3d OFDM system with three-dimensional information characteristics.The coding combination between the information characteristics increases the amount of information and reduces the number of subcarriers,solveing the problem of serious inter-frequency interference in the OFDM system.Third,we have proposed a method of peak-to-average ratio reduction based on machine learning.It takes signals with different pulse amplitudes,pulse positions and sub-carrier frequencies as samples,and uses peak-to-average ratio and bit error rate as loss functions to overcome the problem of rate attenuation and information loss caused by the traditional method of reducing peak-to-average power ratio and to achieve low power consumption and low peak-to-average ratio under the premise of ensuring highspeed information transmissionIn this thesis,according to the collaborative design of multi-module and multi-unit,the above technologies were merged into a system to realize a high-speed,low-latency,low-bit error rate underwater acoustic high-speed communication system,and a sea trial was conducted.The experimental results show that the transmission rate of 500 kbps can be achieved at a distance of 200 m,and the transmission of picture and video format signals will not cause frame jams,which provides an effective solution for underwater medium and long distance underwater acoustic high-speed communication systems.