Performance Evaluation of Free Space Optic Technology Using PPM and OOK Modulation

The increasing trend in developing free space optic (FSO) system technology, which is expected to become an alternative for future high-speed wireless communications based on optical communication system, demands comprehensive performance observation of propagation parameters. So, this research proposes an FSO system model using pulse position modulation and on-off keying modulation by considering the influence and reliability of the system on distance, atmospheric conditions, and variations in aperture diameter. The test results include the bit error rate (BER), Q-factor, and optical and electrical signal-to-noise ratio (OSNR/ESNR) at a bit rate of 2.5 Gbps. Based on result observations of the reliability of the FSO system using PPM and OOK modulation at a bit rate of 2.5 Gbps and an optical lens diameter of 5 cm, the proposed system model is capable of meeting optical communication standards up to a transmission distance of 1 km. Meanwhile, in testing various atmospheric conditions with an optical lens diameter of 5 cm to a distance of 0.5 km, the system model is suitable for use in light fog, very light fog, and light mist to clear air conditions. However, in this test scenario, the system is not feasible for dense, thick, and moderate fog conditions. Furthermore, observations at a distance of 0.5 km show that by increasing the optical lens aperture diameter from 20 cm to 30 cm, the proposed system model can achieve BER values of less than 10−30 to 10−12 in thick fog conditions. In general, there is no significant difference between system performance, including BER, Q factor, and OSNR and ESNR values, whether using PPM modulation or OOK modulation, where the use of a wavelength of 1330 nm is more recommended than 1550 nm judging from the selected signal to noise ratio value. © 2024 Author(s).