A Hybrid Method for Indoor Wave Propagation Modeling

A novel method of analyzing wave propagation in a building consisting of a heterogeneous mixture of homogeneous and periodic walls is presented. In this method walls are discretized into finite-size building blocks and a finite-difference time-domain (FDTD) approach is used to compute their electromagnetic response in a periodic arrangement as well as in corner and terminal locations. These results in conjunction with an iterative field/current calculation algorithm are used to compute the interactions among the walls. The theory and the implementation of this method are described for the 2-D case. The algorithm will henceforth be referred to as ldquobrick-tracingrdquo algorithm. This field calculation leads to more accurate indoor field predictions, as it accounts for multiple scattering from periodic (cinderblocks, rebar structures, etc.) and nonperiodic wall structures and yet is computationally tractable. The FDTD computation of the walls is fast because of the finite and relatively small size of the building blocks and the iterative current computation only uses simple radiation integral calculations. Consequently computational time is much less than any full-wave simulation. At 1.0 GHz, the 2-D approach of this hybrid method is validated with a full-wave FDTD code and its capability to analyze complex indoor environments is shown.