A Computational Model for Path Loss in Wireless Sensor Networks in Orchard Environments

Abstract

A computational model for radio wave propagation through tree orchards is presented. Trees are modeled as collections of branches, geometrically approximated by cylinders, whose dimensions are determined on the basis of measurements in a cherry orchard. Tree canopies are modeled as dielectric spheres of appropriate size. A single row of trees was modeled by creating copies of a representative tree model positioned on top of a rectangular, lossy dielectric slab that simulated the ground. The complete scattering model, including soil and trees, enhanced by periodicity conditions corresponding to the array, was characterized via a commercial computational software tool for simulating the wave propagation by means of the Finite Element Method. The attenuation of the simulated signal was compared to measurements taken in the cherry orchard, using two ZigBee receiver-transmitter modules. Near the top of the tree canopies (at 3 m), the predicted attenuation was close to the measured one—just slightly underestimated. However, at 1.5 m the solver underestimated the measured attenuation significantly, especially when leaves were present and, as distances grew longer. This suggests that the effects of scattering from neighboring tree rows need to be incorporated into the model. However, complex geometries result in ill conditioned linear systems that affect the solver's convergence.

Characterization of the On-Body Path Loss at 2.45 GHz and Energy Efficient WBAN Design for Dairy Cows

“…In order to account for the multipath effect, a ground with the electrical properties of the agricultural soil was added under the cow with a separation of 2 mm. As in [19], an electrical conductivity of 0.1 S/m and a relative permittivity of 3 were considered for the ground at 2.4 GHz. The multipath effect from the walls was negligible because the measurements were performed in a large area.…”

Wireless sensor node modelling for energy efficiency analysis in data-intensive periodic monitoring

“…In our simulations we employ ITU-R empirical model [32]. According to [33], in presence of leaves ITU-R model provides the closest approximation of the measured attenuation in the orchards. The total attenuation in the communication channel can be expressed as a sum of free space attenuation (L FREE ) and ITU-R attenuation (L V EG ) [34] and the resulting received signal power is P r (expressed in dB):…”

Voice-Controlled and Wireless Solid Set Canopy Delivery (VCW-SSCD) System for Mist-Cooling

“…The XBee routers are setup in mesh networking mode extending the network further from the XBee coordinator in the master control unit. Based on [29,30], the tree canopy significantly influences the radio path losses of the WSN; the developed models in [29,30] can be used to estimate the distance between nodes in a WSN in an orchard. This is very critical to scale-up the proposed system.…”