Investigating the effect of turbulence on IPI in a vehicular OCC system using PSF analysis

Abstract

Optical camera communication (OCC) has emerged as a promising technology for wireless communication owing to its enormous potential benefits. However, turbulence conditions can restrict the feasibility of OCC systems that employ multiple-input multiple-output (MIMO) techniques. In this work, we consider a vehicular MIMO-OCC system model in which the traffic light LEDs transmit data streams separately in parallel channels to the camera of a vehicle. We analyze the effect of turbulence on the inter-pixel interference (IPI) and bit error rate (BER) of the low speed vehicular MIMO-OCC system using the point spread function (PSF) of the optical channel. We introduce two performance metrics, i.e., digital number difference (DND) and the percentage of separable LEDs (PSLED) for strong and very strong turbulence conditions, respectively. The parameters of the camera and traffic light LEDs can affect the IPI caused by turbulence. It is shown that the DND of MIMO-OCC systems with larger focal length and LED size less affected by turbulence. In addition, smaller f-number and pixel size reduce the effect of turbulence on DND. It is also demonstrated that very strong turbulence can reduce PSLED for links longer than 20 m. Moreover, if turbulence reduces PSLED, increasing the LEDs’ intensity cannot efficiently reduce the BER in the MIMO-OCC system.