Adaptive Transmission for Coherent OWC With Multiple Parallel Optical Beams

We investigate adaptive transmission schemes for a coherent optical wireless communication system using multiple parallel optical beams. The proposed schemes perform adaptive modulation, transmit power allocation, and beam selection by considering statistical delay constraints. Our analysis and simulation results reveal the following three insights: 1) activating only suitable optical beams and adapting their transmission parameters significantly improve effective rate (ER) in strict delay constraint; 2) at both loose and strict delay constraints, equal power allocation among the suitable optical beams provides near optimal ER in high signal-to-noise-ratio (SNR) regimes; and 3) allocating all the power to the strongest optical beam provides near optimal ER at strict delay constraint and low SNR regimes.