ISSN : 1796-2021
Volume : 4    Issue : 4    Date : May 2009

Modified 2D Finite-Difference Time-Domain Based Tunnel Path Loss Prediction for Wireless
Sensor Network Applications
Yan Wu, Min Lin, and Ian J. Wassell
Page(s): 214-223
Full Text:
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To effectively deploy wireless sensor networks (WSNs) for monitoring and assessing the condition
of tunnels, a Propagation Path Loss (PL) Model, which describes the power loss versus distance
between the transmitter and the receiver for the tunnel environment is required. For most of the
existing propagation measurements that have been conducted in tunnels, the antennas have been
positioned along the central axis of a tunnel. However this is not representative of most
infrastructure monitoring applications where the wireless sensor nodes will be mounted on the
walls of the tunnel. In this paper, the results obtained from conducting close-to-wall measurements
at 868MHz and 2.45GHz in curved arched-shaped tunnels are presented along with predictions
made using a newly proposed Modified 2D Finite-Difference Time-Domain (FDTD) method. Since
most currently available wireless sensor nodes have a communication range less than about
100m, we will focus on path loss measurement and modelling up to a maximum range of several
hundred metres. During our measurements, the antennas are always maintained at a height of 2m,
however the antenna distance to the tunnel wall is varied. By having the PL model as a guideline,
we are able to determine the critical parameters for wireless communication in a tunnel, such as
maximum communication distance, transmit power and receiver sensitivity.

Index Terms
tunnel path loss, FDTD, large scale computing, field measurements