Threshold detection and slot clustering algorithms in DPIM-VLC systems

Abstract

In this paper it is presented two adaptive threshold estimation methods for Digital Pulse Interval Modulation (DPIM) in Visible Light Communication (VLC) systems. First method, which is called I-DPIMwAL, is proposed for mobile users without Ambient Light (AL) while second scheme that is referred to as I-DPIM ensures to accomplish the mobile data transmission under AL effect. Addition to this, the paper introduces a receiver based on K-means algorithm that classifies the logical levels of DPIM slots without using any threshold value. In order to compare with improved methods, two traditional systems are considered in the simulations. The FP-DPIM, which can be called Full Perfect-DPIM, has the perfect knowledge of threshold value that is determined by using both ambient light level and distance between receiver and transmitter whereas HP-DPIM, which can be defined as Half Perfect-DPIM, uses only one static threshold value for all distances between receiver and transmitter. According to experimental results, it can be considered that AL becomes either square wave or exponential signals. In practical systems, FP-DPIM cannot know the threshold value that is caused by ambient light effect however, it was given to obtain the exact performance analysis in simulation results.