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Design of mQAM-OFDM Underwater Wireless Optical Communication System Based on LED Array

In this paper, we design a compact UWOC transmitter based on LED array light source and mQAM-OFDM modulation using FPGA, and a verification system with the transmitter and a low-cost optical receiving module, is experimentally demonstrated. In this system, the LED array is used to enhance the optical power, and a free form lens is designed for beam forming. It is shown by experimental results that this system can achieve data rates up to 50 Mbps over a 5m underwater channel. In addition, the impacts of data rate and deviation of the optical receiver's position from the optical axis on the performance of communication system are also compared. This provides an idea for the practical design of compact UWOC system.