Performance analysis of OOK, BPSK, QPSK modulation schemes in uplink of ground-to-satellite laser communication system under atmospheric fluctuation

Considering the combined effects of the intensity scintillation and the beam wander in the satellite-to-ground laser uplink communication system, the bit error rate (BER) performance of three modulation schemes – on–off keying (OOK), binary phase-shifted keying (BPSK), quadrature phase-shifted keying (QPSK) are investigated. In comparison with the condition in which the atmospheric turbulence is not taken into consideration, conclusions that atmospheric turbulence severely degrades the performance of the system are drawn. Based on the simulation results, the advantages of BPSK are analyzed in contrast with OOK and QPSK. Specially, when transmission power is 4 W, performance of OOK shows 18 dB impairment while performance of QPSK shows 3 dB impairment compared with BPSK under the atmospheric fluctuation. Further compared to QPSK, BPSK owns lower BER and simpler process. Considered the feasibility in communication systems, BPSK should be the most reasonable modulation scheme which can decrease the BER of systems without increasing the transmitter power among these three modulation schemes. Besides, optimum divergence angle, optimum beam radius and appropriate receiver diameter are also analyzed, which is significant in practical applications.