Caracterização bidimensional de canais rádio através de diferenças finitas no domínio do tempo

Abstract

The continuous growth of wireless communication systems and services significantly demands more efficient models for the prediction of the propagation mechanisms of radio waves. Among the methods used for this kind of prediction, the FDTD (Finite Difference Time Domain) has been presented as an efficient tool in the radio channel modeling for its flexibility, accuracy, and efficient visualization of the results. The present work applies the FDTD in the bi-dimensional radio-channel characterization. For this purpose, a study of the inaccuracies associated with numeric dispersion and stability is presented. The study is based on the implementation of the FDTD method as initially proposed by Yee, adding the contributions of other researchers such as Taflove. Absorbing boundary conditions (ABC) were also studied, in order to limit thenumerical implementation of the region of interest. Among the available ABCs, the Perfectly Matched Layer (PML) was chosen for its low spurious reflections, and it was implemented for the bi-dimensional space.In order to demonstrate the applicability of such technique for the radio channel characterization, a micro-cell with six buildings (assumed perfect electric conductors) in an outdoor environment (PML limited), was analyzed and the results compared against those available in the open literature. The results attest the efficiency of the FDTD (combined withthe PML), presenting relative errors of the order of 0.1%, which are basically caused by the spurious reflections and the numeric instability. From the numerical results, the coherent band of the radio channel could be determined.