Research And Design Of Magnetic Induction Underground Communication System Based On SWIPT

Modern industrial production and urban construction are gradually expanding the use of space below the surface,and the following requirements are placed on the development of wireless sensor networks and the Internet of Things: Monitoring of the movement of underground soils and rocks,monitoring of the status of underground facilities,monitoring of the operational status of underground equipment in industrial production,and monitoring of the internal conditions of bridges,dams and tunnels.The traditional electromagnetic wave wireless communication technology is affected by soil,water content and multipath effect when it is transmitted underground,its transmission loss is large,and its penetration is low,which cannot meet the application requirements.Magnetic induction underground communication technology transmits and receives signals by magnetic coupling,which is not affected by soil components and has the characteristics of small path loss and stable transmission channel,which provides a new solution for underground communication.In addition,the working time of the wireless sensor network node is limited by the battery power,and the wireless power transmission technology can solve the problem of the wireless sensor network node' power.In this paper,magnetic induction underground communication technology and wireless energy transmission technology are combined.Field-programmable gate array(FPGA)is used to design a magnetic induction underground communication system based on simultaneous wireless information and power transfer(SWIPT).Firstly,this paper analyzes the principle and information energy allocation method of magnetic induction underground communication based on SWIPT.The magnetic flux density and mutual inductance expressions of the four communication antenna models are given and their magnetic flux density distribution is simulated and characterized,which lays a theoretical foundation for the research and design of the magnetic induction underground communication system based on SWIPT.Then,this paper designs and analyzes the hardware circuit and software of the magnetic induction underground communication system based on SWIPT.The hardware circuit includes an FPGA minimum system,an analog to digital(A/D)and digital to analog(D/A)conversion circuit,a power amplification circuit,an energy receiving circuit and a matching circuit;The FPGA software design includes Quadrature differential reference phase shift Keying(QDPSK)modulation and demodulation software design,A/D and D/A conversion module software design,USB(Universal Serial Bus serial)communication software design,energy receiving module software design and information energy distribution software design.Finally,an experimental platform of magnetic induction underground communication system based on SWIPT is builded and oftware and hardware simulation tests are performed which ensure the accuracy and feasibility of hardware and software design of this system.On this basis,the energy transmission and communication performance of the magnetic induction underground communication system based on SWIPT are tested experimentally,which confirms the feasibility of SWIPT.