Resource Allocation for Downlink OFDMA in Underwater Visible Light Communications

As a wireless connectivity solution with low latency and high capacity, visible light communication (VLC) is particularly attractive for high-speed underwater applications such as image or real-time video transmission. In this paper, we consider the downlink of an underwater sensor network (USN) where the communication between the central command unit and sensor nodes takes place through VLC. The system builds upon DC-biased-optical orthogonal frequency division multiple access (DCO-OFDMA) where subsets of subcarriers are assigned to different nodes. We propose a joint subcarrier allocation and bit loading algorithm in an effort to achieve identical data rate for each node in the USN while satisfying a targeted bit error rate (BER). We further present Monte Carlo simulation results to demonstrate the performance of the proposed adaptive algorithm.