Abstract: A hybrid method of combing ray tracing and finite-difference time-domain (FDTD) method is improved. This method is used to indoor radio propagation numericalmodeling work. The difference equations of the perfectly matched layer (PML) absorbing boundary conditions used in the hybrid method are given. An example is calculated and the resultant graphs reveal that the improvement can reach 15 percent. So, more accurate propagation prediction can be obtained by using the improved method.

Key words: a hybrid method, ray tracing, finite-difference time-domain (FDTD) method, indoor radio propagation