Secrecy and performance analysis of dual hop FSO-RF system using differential chaos shift keying

Abstract Free space optical (FSO) communication system is a promising candidate for day-to-day progressing networks because of its potential advantages such as, large bandwidth, line-of-sight communication, non-licensed spectrum, high data rates and many more. Relay-assisted communication provides an additional hike to the system’s performance by expanding its coverage range, enhancing data rates, capacity and mitigating the effect of turbulence. In this manuscript, FSO-radio frequency (RF) dual hop system is considered using decode and forward (DF) relaying protocol. Furthermore, chaotic signals are incorporated in the proposed system to enhance their confidentiality using differential chaos shift keying (DCSK). This is demonstrated by performing secrecy analysis of the proposed system. Here, it is assumed that FSO link experiences Gamma-Gamma turbulence along with pointing errors while RF link experiences Nakagami-m fading. The probability of error of the proposed system is analyzed, and the results indicated huge gain in the SNR requirements in FSO-RF-DCSK system. Also, secrecy analysis is performed using secrecy outage probability (SOP) as a metric for the proposed system. The findings are noteworthy as FSO-RF-DCSK system presents superior performance in terms of secrecy.