Average BER performance of rectangular QAM-UWOC over strong oceanic turbulence channels with pointing error

We theoretically analyze the average bit error rate (ABER) performance of underwater wireless optical communication (UWOC) systems using rectangular quadrature-amplitude modulation (QAM) over strong oceanic turbulence channels with pointing error. The strong oceanic turbulence channel is assumed to be a gamma-gamma model. The close-form expression for the ABER is derived by using the Meijer's G-function. Based on this expression, various effects of system parameters, including QAM scheme, link distance, diameter aperture, ratio of source beam width to aperture radius, and four oceanic turbulence parameters on ABER performance are taken into account. Simulation results show that applying a smaller rectangular QAM dimension and link distance, or a larger aperture diameter and the ratio of beam width to aperture radius can improve the UWOC quality significantly. The contributions of four oceanic turbulence parameters also need to be considered in practical UWOC applications. The results reported in this paper will be benefit to design UWOC systems.