Pointing error angle evaluation of OFDM inter-satellite optical wireless communication (Is-OWC) on LEO-MEO satellite

Inter-satellite optical wireless communication (IsOWC) is a communication technology between satellites in the same or different orbits. This technology uses light as an optical source to transmit information between satellites in low earth orbit (LEO), medium earth orbit (MEO), to geostationary earth orbit (GEO). Is-OWC has advantages such as low power consumption and high data rates. However, the Is-OWC system has challenges, such as the influence of the pointing error angle parameters on the transmitter and receiver satellites, the wavelength used, and the distance of optical wireless. Apart from that, multiplexing techniques are one way to improve the performance of the IS-OWC system in terms of bandwidth and data rate, such as the orthogonal frequency division multiplexing (OFDM) technique. In the digital communication, quadrature amplitude modulation (QAM) is used to modulate digital signals at high speeds. Therefore, the research aims to analyze the performance of the Is-OWC system by utilizing 4 QAM-OFDM in LEO-MEO communication on the influence of the pointing error angle value with a limited transmission distance of 500 to 5000 km (LEO-MEO). This research varies the influence of the optical source wavelength, namely wavelengths of 1310 nm and 1550 nm, by using continuous wave laser power of 0dBm at a bit rate of 10 Gbps. Based on the results, it can be concluded that for all variations in pointing error angle values from 0 to 5 μrad, the minimum SER value obtained is between 10-45 and 10-20 at a distance of 500 km. However, the SER value of 10-12 can only be achieved on 1550 nm with a maximum pointing error angle of 4 μrad at 1000 km, while wavelength 1310 nm can only be achieved with a pointing error angle of 3 μrad. A significant increase in SER values can be seen when the transmission distance increases from 2500 km to 5000 km, where the SER values obtained are in the range of 10-4 to 10-1 for all variations in pointing error angle values. Regarding the EVM results, obtaining BER and SER values of 10-9 at a distance of 2000 km can only be achieved with a minimum EVM value of 20%.