A Butterfly-Based Domain Decomposition SIE Simulator for EM Analysis of Wireless Communication Systems in Mine Environments

The design, (re)configuration, and EMC certification of wireless communication systems in underground mines call for powerful simulators capable of analyzing electromagnetic (EM) wave propagation in electrically large and complex mine tunnels and galleries. Full-wave EM simulators are a perfect fit for this task were it not for the fact that they require enormous computational resources. To reduce their computational costs, we recently proposed a memory and CPU efficient, full-wave, domain decomposition-based surface integral equation (SIE) simulator (Sheng et. al., Proc IEEE Int. Symp. Antennas Propagat., 2016). This simulator proceeds in three stages: (i) First, it subdivides mine tunnels and galleries into subdomains separated by equivalent surfaces. (ii) Next, it computes scattering matrices that characterize EM wave propagation between the equivalent surfaces bounding each subdomain. (iii) Finally, it constructs and solves a global inter-domain system that accounts for EM interactions between subdomains. This simulator oftentimes is many times faster than a single-domain simulator, especially when the structure contains many identical subdomains (Sheng et. al., Proc IEEE Int. Symp. Antennas Propagat., 2016). That said, its cost remains prohibitively high, especially when applied to the analysis of high frequency communication systems for which the equivalent surfaces separating subdomains support thousands of basis functions. This high cost stems from the fact that the simulator computes scattering matrices one column at a time via the repeated iterative solution of a Poggio-Miller-Chang-Harrington-Wu-Tsai (PMCHWT) SIE for all possible excitations of the equivalent surfaces bounding subdomains.