Secure free space optical communication based on chaotic key

Abstract

This thesis presents the simulation and validation of a secure Free Space Optical (FSO) communication system, tailored for next-generation 5G networks. To overcome the inherent vulnerabilities of FSO links—such as atmospheric interference—a chaos-based encryption technique is proposed, leveraging Chua’s circuit for dynamic key generation. A technical analysis of FSO and 5G technologies highlights their key advantages, including high data throughput, low latency, and immunity to electromagnetic interference, while also addressing the challenges associated with their deployment. Chaotic encryption stands out as a promising solution due to its strong nonlinearity, sensitivity to initial conditions, and low computational complexity, making it particularly well-suited for physical-layer security. Cryptographic evaluation confirms high entropy (0.99943), strong sensitivity (MSE = 0.518), and a vast key space (∼ 2^131). The presence of a positive Lyapunov exponent (λ1 ≈ 0.648) further validates the chaotic behavior of the system. The system is validated through simulations using Matlab and OptiSystem under various operational conditions: data rates from 1 to 10 Gbps, distances up to 1.5 km, and atmospheric attenuations up to 8 dB/km. The results demonstrate excellent performance, maintaining a Bit Error Rate (BER) below 10−6 and outperforming non-secure configurations in terms of signal integrity, Q-factor, and eye diagram analysis. Overall, this study shows that chaos-based encryption is a secure, high-performance, and scalable solution for future 5G optical wireless infrastructures.