Résumé:
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.
