ABER and outage probability of FSO systems under UAV-assisted symbol-level jamming over turbulent channels with pointing errors

Abstract

Free-space optical (FSO) communication systems are emerging as a viable technology for 6G, offering a compelling combination of cost-effective installation, high data throughput, extensive reach, and minimal latency. However, these systems are susceptible to potential intrusions, particularly jamming attacks, which pose a significant threat to their reliability and performance. We analyze the average bit error rate (ABER) and outage probability (OP) for phase-shift keying (BPSK)-modulated FSO systems under Unmanned Aerial Vehicle (UAV)-assisted jamming. The proposed system model includes both the legitimate and jamming channels, accounting for atmospheric turbulence (AT) and pointing errors (PE). The probability density functions (PDFs) of the signal-to-noise ratio (SNR), signal-to-jamming ratio (SJR), and signal-to-jamming-and-noise ratio (SJNR) are derived, which serve as the foundation for our ABER analysis. Closed-form expressions for the ABER and OP under BPSK modulation are derived for various jamming conditions, including coherent and non-coherent symbol-level jamming (SLJ), as well as noise jamming scenarios. Numerical analysis and Monte Carlo simulations are conducted to investigate the effects of AT and PE on system performance across various jamming conditions. Results indicate that AT in the legitimate channel significantly impacts system performance, with coherent SLJ yielding higher ABER than non-coherent SLJ. The phase difference between jamming and legitimate signals critically influences jamming effectiveness, where orthogonal phases minimize disruption. Furthermore, jamming signal pointing accuracy directly correlates with ABER degradation—higher precision induces elevated error rates. This study provides valuable insights for designing robust, jamming-resistant FSO systems.