The Combined ECC Scheme with Outer 3-Bit BEC and Inner SEC-DAEC Codes for FSO Communication System

Free space optical (FSO) communication systems are considered as the essential building block of beyond 5G communication standards due to their higher speed of operation and utilization of unlicensed frequency spectrum. But the performances of FSO systems are immensely affected by atmospheric turbulence (AT) conditions. The coded-FSO (C-FSO) systems which utilize error correction code (ECC) in the primary FSO links have been preferred frequently for their improved performances against different AT conditions compared to uncoded-FSO (U-FSO) systems. In this paper, three error correcting codes (ECCs) namely 3-bit burst error correction (BEC), single error correction–double adjacent error correction (SEC-DAEC), and combined ECC scheme have been proposed for atmospheric turbulence (AT) FSO communication systems. The gamma–Gamma fading distribution has been used to describe the severity of atmospheric turbulence in the propagation path. The closed-form expressions of average bit error rate (ABER) of U-FSO and proposed C-FSO systems have been derived in terms of Meijer’s G function. All the analytical ABER outcomes of U-FSO system and proposed C-FSO systems have been verified with Monte Carlo simulation. However, the proposed combined ECC C-FSO system has been observed to exhibit the highest ABER improvements in all the AT regimes. Present work can be extended by incorporating different diversity schemes along with C-FSO systems in future.