Photon-counting schemes for MIMO underwater wireless optical communication with arrayed PMTs.

Underwater wireless optical communication (UWOC) is a promising means of realizing large capacity and high rate in aquatic media. In this paper, a photomultiplier tube (PMT)-based multiple-input multiple-output (MIMO) UWOC system is investigated. Photon counting is an effective technique used to detect very low-level light. A PMT with an excellent photon-counting mode is adopted, and the performance in terms of the bit error rate is discussed. The received optical power can be predicted based on the detected photocount in each symbol period, and the received photocount distribution may be simulated through MATLAB. Furthermore, the optical link model and energy per bit with on-off keying are evaluated for different water types at a 10 m optical link distance. This MIMO-UWOC system combines the advantages of PMTs and the MIMO scheme and has the potential to realize long-distance optical link transmission.