Multi-User Scheduling and Channel Characteristics for Water-to-Air Unmanned Vehicular Visible Light Communication

In this paper, assuming that several underwater unmanned vehicles transmit data to one unmanned aerial vehicle above the water surface, we consider a multi-user water-to-air visible light communication system under wavy water conditions. Through Monte Carlo simulation and experiments, we extract link gains and analyze their statistic characteristics under different angles between the user line and the wave direction. Then, we propose two categories of scheduling schemes, namely scheduling schemes with and without interference among users, which are implemented under fixed-rate mode and delay-based allocated-rate mode, respectively. Moreover, we analyze the average system throughput and fairness of each scheduling scheme under different rate modes. The results show that simultaneous transmission schemes perform better in fixed-rate mode while orthogonal transmission schemes have higher throughput and are fairer in allocated-rate mode.