This study presents the modified wavefront decomposition method as a new ray-tracing acceleration technique for indoor propagation modelling. In this method, the exact propagation paths of the rays that reach the receiver after multiple reflections and/or refractions are calculated. Thus, the electromagnetic field at the receiver is obtained with a high accuracy. When only reflections are considered, our method simplifies to the multiple image theory or shooting and bouncing ray/image approach already available in the literature. However, the modified wavefront decomposition method calculates the exact propagation paths toward the receiver even if the rays encounter multiple refractions or a sequence of reflections and refractions. This novel contribution is specially important in indoor applications where through-the-wall propagation is usually noticeable. The significance of the proposed method is that the accuracy in the received field is obtained by shooting a few rays to the space around the transmitter. Consequently, a considerable reduction of the simulation time is achieved. The simulations show that the proposed method outperforms the traditional wavefront decomposition method. Furthermore, concurrent application of the proposed method and the previously published acceleration techniques is shown possible, which results in simulation time reduction of more than 11 times for a typical simulated indoor environment.

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