Performance Analysis of Differential Chaos Shift Keying in Free Space Optical Communication With Diversity Techniques

This paper explores the performance of a single input multiple output (SIMO) free space optical (FSO) communication system using differential chaos shift keying (DCSK) with diversity combining techniques. Specifically, the paper presents the use of maximal ratio combining (MRC), equal gain combining (EGC), and selection combining (SC) diversity techniques for the DCSK-FSO system. Adding chaos to FSO systems using diversity can significantly improve the reliability and the system performance, making them a promising option for various 5G/6G wireless applications. The inherent properties of chaos, such as security, wide band nature, and immunity to fading, make it an attractive option for FSO communication. The Gamma-Gamma turbulence model was used to characterize the FSO link, and the system’s performance was analyzed in terms of bit error probability across varying atmospheric turbulence levels, link lengths, and numbers of receivers. The results indicate that under the same system conditions, MRC/EGC performs 2–4 dB better in terms of error probability than the SC diversity technique. Furthermore, the SIMO-DCSK-FSO system presents a substantial improvement in diversity gain, with around 30 dB for moderate turbulence and 37 dB for strong turbulence.