Study Of Electromagnetic Transmission In Soil Media Based On Wireless Underground Sensor Network

This paper aims at studying wireless underground sensor network, works to reveal thegeneral characteristics of electromagnetic wave transmission in cultivated horizon soil, andprovides the basis support for further research and building of wireless underground sensornetwork.In the paper, soil water content was seemed as the test object, under the condition ofdifferent nodes RF frequencies, soil water content, buried depth and horizontal distance ofsensor nodes, electromagnetic wave transmission characteristics was studied throughcomputer simulation, indoor test and field underground measurement by using the developedlow power wireless underground sensor network nodes. Two dimensional and Threedimensional relation models of the electromagnetic properties, soil properties andexperimental environment parameters were established, and the transmission characteristicsof WUSN electromagnetic wave in soil were put forward under the condition of the generalcomputer simulation, indoor ideal conditions and field measurement. The following resultswere obtained:(1) It preliminarily identified that the nodes frequencies, nodes burial depth, horizontalinternodes distance, soil water content factors were the main influence factors on thetransmission of electromagnetic wave in the soil.Agricultural wireless underground sensor network architecture, types and communicationmode were studied. In the condition of the wireless underground sensor network nodefrequency were240MHz,433MHz and868MHz, nodes burial depth were in the range of10cm to100cm, the internodes horizontal distance changed from100cm to1000cm and soilwater content changed between5%and30%, the communication of wireless undergroundsensor network electromagnetic wave in the soil medium was feasible.(2) The basic characteristic parameters relationship of WUSN node through-the-earthtransmission were established.Through-the-earth communication mode of aboveground-underground andunderground-aboveground on different sink node deployed, the comprehensive effects of thenode burial depth and soil water content on communication were analyzed, two dimensional relation between the horizontal internodes distance, the soil water content and the receivedsignal strength, communication error rate was obtained.(3) The basic characteristic parameters relationship of WUSN internodes undergroundtransmission were established.In the wireless underground sensor network internodes communication, the influence ofthe nodes burial depth, the horizontal internodes distance and the soil water content on thereceived signal strength is a quadratic relationship, communication error rate changed in theway of exponentially, the linear and quadratic relationship in different cases.(4) The basic characteristic of WUSN electromagnetic wave under specific frequencytransmission in the soil were established.When WUSN node frequency was433MHz, the comprehensive effects of nodes burialdepth, the horizontal internodes distance and the soil water content on communication werestudied. Three dimensional relation of the nodes burial depth, the horizontal internodesdistance, the soil water content and the received signal strength, communication error ratewere obtained, and the basic characteristic of the electromagnetic wave transmission in thesoil was established.Agricultural wireless underground sensor network is a new research direction, theresearch on through-the-earth communication, underground transmission and undergroundnetwork of electromagnetic wave in the farmland soil is still at the initial stage. Especially,there are a lot of content available for study about the transmission characteristics of wirelessunderground sensor network electromagnetic wave in soil medium and the several factorscomprehensive influence.The paper is only a exploratory research, the main research resultsare obtained in the laboratory, further studies in the field are needed in the future.