Connectivity in Wireless Underground Sensor Networks

This paper investigates the probabilistic connectivity of the Wireless Underground Sensor Networks (WUSNs). Due to the unique channel characteristics and the heterogeneous network architecture of the WUSNs, the connectivity analysis is much more complicated than in the terrestrial wireless sensor networks and ad hoc networks. To our knowledge, this connectivity problem in WUSNs was not addressed before. In this paper, a mathematical model is developed to analyze the probabilistic connectivity in WUSNs, which captures the effects of environmental parameters such as the soil moisture and soil composition, and system parameters such as the operating frequency, the sensor burial depth, the sink antenna height, the density of the sensor devices, the tolerable latency of the networks, and the number and the mobility of the above- ground sinks. The lower and upper bounds for the connectivity probability are derived analytically. Simulation studies are performed, where the theoretical bounds are validated, and the effects of several environmental and system parameters on the performance of these networks are investigated.