The progress of the wireless digital communication system during the last years
has been remarkable, and today is one of the fields with faster development.
There is a growing search in propagation models that provide efficiency and
accuracy. The study of the radio propagation in these environments is very
important for the determination of the propagation losses in indoor environment,
because any object with dimensions in the order of greatness inside of the range
of mobile communication wavelength can act as an interference source for the
electromagnetic waves. Two types of propagation models are very used for indoor
environment: the empirics and the deterministic. The first ones are based on very
simple and direct formulas, easy to apply, however they provide local-specific
precision. The deterministic models follow propagation of electromagnetic waves
physical principles - the most popular are the ray tracing and the numeric solution
of the equations of Maxwell (elliptic equations and for approach, parabolic
equations). In this work is proposed a model based on the method of parabolic
equations, being considered narrow angles (up to 15°) and wide angles (up to 90°)
of propagation. For the solution of the parabolic equation for small propagation
angles, the implicit finite difference scheme of the Crank-Nicholson type was used;
and for the solution of the equation that considers wide propagation angles the
mixed Fourier Transforms was used. In order to validate the model proposed,
measurement campaigns were carried out in frequencies of 900 MHz and 2.4 GHz
and the data obtained from these campaigns were compared to the model
proposed in this work. Besides, the model in subject was also compared with
some existent models in the literature. The results found in this work validate the method of parabolic equations as an important tool for the calculation of the
propagation loss in indoor environment, once a great reduction of computational
effort and quantity of necessary memory, when compared the other methods and
a better result was observed for wide propagation angles.
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