Performance research of mPPM-QPSK modulation signal for free space optical communication

Abstract

We establish a free-space optical (FSO) coherent optical communication system using mPPM-QPSK modulation formats, which implements 10 Gbps mPPM-QPSK signal FSO transmission. The BER performance of mPPM-QPSK under different atmospheric turbulence intensity is investigated experimentally and compared with traditional QPSK modulated signal. Experimental results of mPPM-QPSK (m=2, 4 and 8) compared with QPSK at BER=1×10−3 show that receiving sensitivities can be improved by 1.7 dB, 4.7 dB and 7.8 dB under weak turbulence, 1.8 dB, 4.9 dB, and 8.7 dB under moderate turbulence, 1.5 dB, 3.9 dB, and 6.3 dB under strong turbulence.