Computer simulations for a site-specific modeling of indoor radio wave propagation

Abstract

Modeling of the indoor radio wave propagation accurately is important in order to design and plan wireless LAN (WLAN) networks in the indoor environment. Computer simulations are convenient methods for the purpose. Until now, it was reported that large-scale electromagnetic simulations using the finite difference time domain (FDTD) method could assess characteristics precisely because of its high ability to model an indoor environment numerically. Although they require rich computer resources and longer running times than the other methods, these problems can be solved by using cluster computer systems. During the work it was found that numerical results depended considerably upon the numerical models of indoor environment. An office building consists of primary structures such as concrete walls and floors, and includes furniture in rooms and reinforcing rods in the concrete walls. All components of the structure can be considered in the numerical model. However, it is desirous that a precise modeling of the indoor propagation is carried out using the simpler numerical model. The paper carries out numerical electromagnetic simulations for an indoor radio wave propagation in a whole floor with a WLAN access point at the frequency of 2.4 GHz, and discusses a relationship between the numerical model and the simulation result. It is showed from the consideration that the measured result of received signal strength indicator is almost similar to the numerical result for only the primary structure such as concrete walls and floors. On the other hand, assessments of electric field distributions and Poynting vectors clarify that besides the primary structure, the furniture should be taken into account to predict propagation paths, delay profiles and signal arrival angles precisely.