PPM- and GMSK-based hybrid modulation technique for optical wireless communication cellular backhaul channel

Abstract

In this study, a hybrid modulation technique called PPM-GMSK, based on the pulse position modulation (PPM) and phase-sampled Gaussian minimum shift keying (GMSK) technique, is investigated by considering log-normal and gamma- gamma turbulence as the channel-fading statistics. The analytical bit error rate (BER) and outage probability of the proposed hybrid modulation are derived. The results show that the hybrid modulation technique is an efficient technique to improve the performance of optical wireless communication for a cellular backhaul channel. Compared to 2-PPM and minimum shift keying (MSK), the proposed hybrid scheme has a less BER and a reduced amount of outage probability. Moreover, to achieve a reliable voice communication at 2 Gbps bit rate and BER of 10-3 under a weak turbulence effect, the PPM-GMSK has a coverage distance of about 3 km, whereas for PPM and MSK it is 2.6 and 2.4 km, respectively.