Adaptive TLS-OQSM technology of a wireless optical MIMO communication system over an oceanic vertical turbulence channel.

Abstract

In this paper, we construct a wireless optical MIMO system based on the ocean power spectrum in the vertical channels, which is suitable for any sea depth under the combined effects of ocean turbulence and pointing errors. Thereby, an adaptive transmit laser selection-optical quadrature spatial modulation (TLS-OQSM) technology is proposed to improve its effectiveness and reliability of communication. The adaptive TLS-OQSM employs the channel adaptive bit mapping (CABM) to grouping and spatial mapping for laser diode (LD) indices based on limited feedback bits for the adaptive signal modulation and power allocation (PA). Simulation results show that the average BER of the system can be efficiently reduced by applying the adaptive TLS-OQSM scheme at different depths in seawater where optical transceivers are deployed, with different pointing errors and different predefined spectral efficiencies.