On Link Misalignment for Underwater Wireless Optical Communications

In wireless optical communications, laser sources have narrow divergence angles and therefore require precisely aligned links, which may increase system complexity and is hard to implement in practice. In the underwater environment, however, the diffuse light field formed at the receiver side due to the scattering property of seawater may reduce the requirement of link alignment. We investigate the performance of link misalignment for underwater wireless optical communications (UWOC) and present a closed-form expression of relationship of transmit power, link range and receiver offset distance. Numerical results suggest that, regardless of water types, an appropriate receiver offset distance is permitted with specific transmit power and link range for reliable communications.