Secure transmission in a W-band RoF system based on delta-sigma modulation.

Area of Science:

• Optical Communications
• Signal Processing
• Cryptography

Background:

• Radio-over-Fiber (RoF) systems are crucial for high-speed data transmission.
• Ensuring secure data transmission in RoF systems is a growing challenge.
• Existing encryption methods may lack robustness against advanced attacks.

Purpose of the Study:

• To propose and validate a novel delta-sigma modulation (DSM) encryption technique for W-band RoF systems.
• To enhance the security and reliability of encrypted signals in hybrid fiber-wireless transmission.
• To improve system sensitivity and resist sophisticated cyber threats.

Main Methods:

• Implementing DSM with variable over-sample ratios (OSRs) on Quadrature Amplitude Modulation-Orthogonal Frequency Division Multiplexing (QAM-OFDM) signals.
• Utilizing chaotic systems for key generation and constellation masking for signal disturbance.
• Employing bit bidirectional diffusion scrambling to counter chosen-plaintext attacks.

Main Results:

• Achieved a high-order QAM-OFDM-DSM encrypted signal with enhanced security.
• Demonstrated superior security compared to single OSR DSM signals over 50-km SSMF and 3-m wireless channels.
• Observed a sensitivity gain of approximately 1 dBm under identical transmission power.
• Verified signal recoverability meeting the hard decision-forward error correction (HD-FEC) threshold of 3.8 × 10^-3.

Conclusions:

• The proposed DSM encryption technique offers a robust solution for secure W-band RoF systems.
• The method provides enhanced security and improved sensitivity, outperforming simpler DSM approaches.
• The system demonstrates reliability and meets stringent error correction requirements for practical deployment.