Experimental characterisation and modelling of the reflection of infrared signals on indoor surfaces

The performance of non-line-of-sight indoor wireless infrared communication systems depends on the reflection characteristics of the surfaces that surround the communication space. This paper presents a set of measured reflection patterns of the most common indoor surfaces and the approximation of those experimental patterns using two reflection models, that of Lambert and of Phong. The results show that the reflection pattern of many surfaces present a strong specular component. Those patterns are well approximated by the model of Phong, but not by that of Lambert. It is also shown that the use of the model of Lambert to approximate the reflection pattern of specular surfaces can lead to errors of several decibels in the evaluation of the propagation losses