Propagation Characteristics Of The Underground-To-Aboveground Communication Link About 2.4ghz And 433mhz Radio Wave: An Empirical Study In The Pine Forest Of Guizhou Province

Wireless Underground Sensor Network (WUSN) is an emerging research area. They are used in many fields from intelligent irrigation to safety and assisted navigation [1]. Wireless underground sensor networks (WUSN) also enable a wide variety of novel applications [2], [3], including soil condition monitoring, earthquake and landslide prediction, underground infrastructure monitoring, sports-field turf management, landscape management, border patrol and security, and etc. Although Traditional wireless communication techniques using electromagnetic (EM) waves encounter three major problems in underground environments: the high path loss, the dynamic channel condition and the large antenna size [4]. However, given the great value of wireless underground sensor networks, further research is necessary, and which also stimulates the interest of many scholars at home and abroad. Channel model is essentially important to WUSN study. There are many relevant studies on Channel Model of WUSN such as in [5][6][7]. By comparison, and according to the condition of pine forest in Guizhou province, we choose a relatively appropriate path loss model in [7]. We will discuss the selected model later. In this paper, two CC2530 RF communication modules and two NRF905 RF communication modules are used to carry out Underground-to-Aboveground communication experiment, respectively, through the experimental study we can find the communication characteristics of Underground-to-Aboveground communication link of wireless underground sensor network of pine forest in Guizhou province. In this paper, the influence of the depth of the underground node on the communication effect is mainly studied. The height of the receiver is divided into three gradients of 70,100,130cm, and the depth of the underground module is divided into five gradients of 5, 10, 15 and 20cm.