基于土壤湿度的无线地下传感网信道传播模型分析

WUSN(Wireless Underground Sensor Networks) is a kind of special network, its radio signal is transmitted underground, so the signal is inflected by soil characteristic. Recently researchers have noticed the remarkable influence of soil moisture, but only certain kinds of wireless underground channel are discussed based on specific soil moisture conditions. In this paper, a wireless underground channel model is established through the variable of soil moisture. When soil moisture is changed continuously, wireless underground channel path loss is studied under different operation frequency and transmission distance. Wthin 300Mhz ~2.4Ghz range, numerical results show that the path loss decrease slower under lower operation frequcency when soil moistures increase, moreover the transmission distance is increased; the path loss increase faster under higer operation frequcency when soil moistures increase, so the higer frequency is not suitable for underground long distance transmission, higer frequency is more sensitive to soil mositure variation, so we can invert wireless underground path loss to soil moisture value, effective detection of soil moisture could be archieved by measuring path loss of wireless underground channel.