Orthogonal Frequency Division Multiplexing for Underwater Optical Wireless Communications

This paper presents the implementation of orthogonal frequency division multiplexing (OFDM) in underwater optical wireless communication (UOWC). The OFDM signal is encoded with quadrature amplitude modulation (QAM) and transmitted using a blue light emitting diode (LED) through a range of water conditions. The underwater link is initially characterised, then the effect of turbidity on the link performance is investigated. The error performance of QAM-OFDM transmission deteriorates as the turbidity increases. Finally, bit and power loading technique is applied to maximise the available data rate for the channel conditions.