Reliable Rotation Transform Aided MIMO Scheme for Underwater Visible Light Communication

Underwater visible light communication (UWVLC) system suffers the performance degradation from the channel absorption, scattering, and turbulence effects. In this paper, we propose a rotation transform (RT) aided transmission scheme for multiple input multiple output (MIMO) multiuser UWVLC systems to improve the system reliability performance in the underwater environment. In our design, firstly we apply the SVD algorithm to convert the MIMO channel into equivalent parallel transmission channels, with the aim to facilitate the receiver to combat the interferences from other users. Then, we propose the rotation transform aided modulation design to adjust the direction of the transmitted constellation, which can enlarge the distance between any two transmitted vectors and thus improve the reliability performances. Simulation results show that the proposed scheme can achieve better reliability performances than the repetitive coding (RC) scheme, spatial multiplexing (SMP) scheme and spatial modulation (SM) for multiuser UWVLC systems in both turbulence and turbulence free scenarios.