Investigation into the sensitivity of the power predictions of a microcellular ray tracing propagation model

This paper investigates the sensitivity of the three-dimensional (3-D) ray tracing microcellular model presented in Astanasiadou et al. (1995, 2000). The variation of the received power is examined for different ray permutations, wall characteristics, antenna position offsets and database inaccuracies. Predictions of the different configurations in line-of-sight (LOS), non-LOS (NLOS), and deep shadow areas are compared with each other and also with narrowband measurements. The analysis illustrates that although the model produces reliable results with five orders of reflection and one order of diffraction, higher orders of reflection and double diffracted rays enhance the model's performance in deep shadow areas. It is also shown that good agreement with measured results can be obtained for wall conductivity in the order of 10-3 S/m and values of relative permittivity around five. The sensitivity analysis to the antenna positioning and database inaccuracies indicates that the receiver positions which suffer the highest power deviations are those at the boundaries of the LOS areas, as well as the positions in the deep shadow regions. In general, for antenna offsets up to 1 m, the predictions of the model are not significantly affected. Finally, the building databases with 1m maximum displacement do not have severe effects on the predictions, but databases with less accuracy can seriously degrade the performance of the model