Detection Algorithm for Overlapping LEDs in Vehicular Visible Light Communication System

In a vehicular visible light communication system, the visible light signals are obtained from a series of image frames showing LEDs as a transmitter which are captured by a high-speed camera as a receiver. However, when two LEDs overlap in the captured image, some serious problems related to data transmission arise, such as high data loss and bit-error-rate. To resolve these problems, in this paper, a method comprising three main steps for separating the overlapping LEDs is proposed. First, according to LED luminance, the edges of the LEDs are detected by applying an improved Canny edge detector algorithm. Then these edges are used to extract all the contours of the two overlapping LEDs. Finally, a derivative of the generalized Hough transform algorithm is utilized to distinguish each LED from the overlapping region according to the obtained LED contours. The performance of the proposed algorithm under different parametric conditions in real situations is analyzed according to the results of experiments conducted in an outdoor environment.