Models and algorithm for the calculation of the impulse response on IR-wireless indoor channels

Abstract

Recently there has been growing interest in using infrared (IR) light for broadband indoor wireless communications. There are two major limitations for establishing a wideband infrared communications link. The first and most important limit is the power requirements of such a link. The second important impairment is the intersymbol interference caused by multipath dispersion. The use of angle-diversity receiver allows to achieve high optical gain and a wide field of view simultaneously, it can reduce 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. The advantages achieved depend on how signal received in the different elements are detect and processed. For this reason, we have developed a fast simulation tool that allows to study the influence of the IR channel and to propose new techniques and receiver structures for those systems. The indoor optical channel simulation can significantly benefit the design of high performance IR systems, but requires models that fit correctly the channel characteristics. In contrast to previous works, we define new models for the emitter, lenses, receiver, nonimaging concentrators and reflectors upon which a Monte Carlo ray-tracing algorithm allows to study different links. The inclusion of these models benefit the design of IR links since the are nearer to real behavior than the ideals models. The use of this simulation tool allowed us to analyze the behavior of several links and suggest a configuration of a receiver using angle diversity.