Hybrid representations for indoor propagation modeling

The local character of the ray fields is a definite advantage when computing the fading and in particular the group delay characteristics of indoor channels in complex environments. However, even in idealized problems computation time requirements may become excessive as the maximum number of reflection and transmissions included in the ray representation under consideration increases. The local mode (LM) and parabolic equation (PE) provide global propagators; they advance the given field distribution on an initial surface to another surface. PE has some definite advantages over ray tracing (RT) for a class of indoor propagation phenomena wherein the prime interest is the determination of the fading characteristics of the channel. Although PE can be also utilized in arrival time calculations, it becomes inefficient since computations have to be performed in the frequency domain. Here we investigate the advantages one may gain from a hybrid technique based on the RT and PE methods and attempt to contact the strong sides of both methods. We obtained the results in idealized model environments; these indicate that the proposed method is both accurate and also computationally efficient.