Extended Kalman filter-aided alignment control for maintaining line of sight in optical communication

Light-emitting diode (LED)-based optical communication is emerging as a low-power, low-cost and high-data rate alternative to acoustic communication. However, it requires a close-to-line-of-sight link between the transmitter and the receiver. Alignment for maintaining line of sight is challenging due to the constant movement of the underlying mobile platform that is caused by unwanted disturbances and/or the propulsion. In this work we propose a novel extended Kalman filter (EKF)-based alignment algorithm, which estimates the relative orientation between the receiver and the transmitter based on the received light intensity, and uses the latter to adjust the scanning motion of the receiver. The scanning pattern is designed such that the rank condition for EKF convergence is satisfied. The efficacy of the proposed estimation and control scheme is illustrated with simulation results and preliminary experimental results.