Error performance analysis of PPM-and FSK-based hybrid modulation scheme for FSO satellite downlink

Abstract

To enhance the error performance of satellite downlink optical wireless communication system, a hybrid modulation scheme called PPM-FSK-SIM is proposed in this study. It is based on the concept of pulse position modulation (PPM), M-ary frequency shift keying (MFSK) and subcarrier intensity modulation (SIM). The analytical bit error rate (BER) of the proposed hybrid scheme is derived, in the presence of atmospheric turbulence with avalanche photodiode (APD) detection by using Meijer-G, which stands out as a reliable and efficient analytical tool that replaces the time-consuming Monte-Carlo simulation method to target a desirable BER. It is analysed over additive white gaussian noise (AWGN), log-normal and gamma–gamma channel models for geostationary satellite to Earth (downlink) communication. As compared to PPM and minimum shift keying (MSK), PPM-MFSK-SIM gives better error rate performance. The scheme is power efficient making it a favourable modulation technique for satellite downlink communication.