Frequency diversity evaluation using modified 2D finite-difference time-domain technique for tunnels and below ground fire hydrants

In comparison with a wired sensor network, a Wireless Sensor Network (WSN) has the potential for easy deployment and increased flexibility and so enabling efficient and low cost condition monitoring of aged civil engineering infrastructure. We will address two wireless communication scenarios, firstly between wireless nodes within a tunnel and secondly for a below to above ground situation where one of the wireless nodes is located in a below ground fire hydrant (FH) chamber. Frequency Diversity (FD) is one method that can be used to address the problem of link unreliability owing to multipath induced fading. However, no quantitative investigation on the potential performance gains from the use of FD in these scenarios has previously been presented. In this paper, by applying our newly developed modified 2D Finite-Difference Time-Domain (FDTD) approach, we investigate the benefits of applying the FD technique in these environments.