Sectored receivers model for calculation of the impulse response on IR wireless indoor channels using Monte Carlo based ray-tracing algorithm

Abstract

The indoor optical channel simulation can significantly benefit the design of high performance infrared (IR) systems, but requires algorithms and models that accurately fit the channel characteristics. One of the limitations of the IR links is the intersymbol interference caused by multipath dispersion. For fixed emitter and receiver locations, multipath dispersion is completely characterized by the channel impulse response. Therefore, to have an algorithm and a propagation model that allow us to determine the impulse response for different IR links is necessary. The use of angle-diversity receivers makes possible the reduction of the impact of ambient light noise, path loss and multipath distortion, in part by exploiting the fact that they are often received from different directions than the desired signal. Basically, there are three ways to get angle-diversity detection: using conventional, imaging or sectored receivers. In contrast to previous works, we present a model for sectored receivers, that is, a set of photodiodes placed in hemispheric form, upon which a Monte Carlo based ray-tracing algorithm allows us to obtain the impulse response and to study those optical links that are characterized by the use of sectored receivers. Using the obtained results, it is possible to establish those parameters of the sectored receiver structure that better performances present with respect to the IR channel features: the path loss and the rms delay spread.