Indoor LED-Based identification systems using adaptive MMSE equalizer for optical multipath dispersion reduction

In this paper, we investigate a novel identification (ID) system using LED light as emitter, named as LED-ID. In such a system, the optical signals are typically modeled as a reflection component and a directed line of sight (LOS) component, since the signals are transmitted over the non-directed LOS links. Therefore, inter-symbol interference (ISI) induced by multipath dispersion that results from optical signals passing through more than one path critically influences the performance of optical wireless (OW) communications. In this paper, we propose the adaptive MMSE equalizer scheme to suppress the multipath ISI, since this scheme can minimize the mean square error (MSE) between the desired equalizer output and the actual equalizer output. We compared the following two algorithms: least mean square (LMS) and recursive least square (RLS). Our computer simulations demonstrated that LED-ID using an adaptive MMSE equalizer can alleviate the serious effects of optical multipath dispersion.