Performance enhancement of FSO based multi carrier system using DP-QPSK and Manchester coding in weak to strong turbulence regime

This research article proposes a coherent optical orthogonal frequency division multiplexing (CO-OFDM) based free-space optic (FSO) system using Manchester data encoding format. Here the CO-OFDM sub-carriers are mapped with dual-polarized quadrature phase-shift keying (DP-QPSK) modulation. Here the prime design objective is to improve the error performance and receiver sensitivity of FSO based system in the presence of low to high atmospheric turbulence. The level insensitivity and self clock extraction of the Manchester coding scheme, it is used for higher-level intensity fluctuation tolerance in the FSO based systems. Here the overall system performance of the proposed design is investigated for both terrestrial FSO and inter-satellite optical wireless communication systems. The combined technological benefits of CO-OFDM, DP-QPSK along with the Manchester encoding scheme in the proposed design have resulted in a FSO link distance of 2.58 km in low turbulence and 2.42 km in high turbulence regime. Similarly, an inter-satellite link distance of approximately 35,000 km has been achieved for successful data transmission at the targeted FEC value of BER. The effectiveness of the proposed system has also been examined with related mathematical analysis.