Time-Domain Repetition Coding for MISO Transmission over Free-Space Optical Channel

In this paper, we suggest a multiple-input/single-output (MISO) transmission technique for free-space optical links with intensity modulation and direct detection. Specifically, time-domain repetition coding is investigated over slow and weak turbulence fading channels, where we suggest a set of efficient codewords for MISO transmission with time-domain repetition coding. The proposed approach increases signal to noise ratio (SNR) most effectively by allocating total radiated power fully into only one transmit aperture for a single bit period with postprocessing followed by equal gain combining at a receiver. We evaluate instantaneous electrical SNR and conditional bit error rate (BER) numerically. Numerical results show that as the number of transmit apertures increases the BER performance gap increases, which reveals its outperformance over other schemes not only in weak turbulence channels but also in weak turbulence channel with misalignment problem.