Beyond-line-of-sight physical-layer chaos communication based on troposcatter.

Area of Science:

• Wireless communication
• Chaos theory
• Physical layer security

Background:

• Traditional line-of-sight communication is limited by obstructions.
• Troposcatter links offer potential for beyond-line-of-sight (BLOS) communication.
• Chaos synchronization provides a basis for secure physical-layer communication.

Purpose of the Study:

• To propose and demonstrate a BLOS physical-layer chaos communication scheme using troposcatter.
• To investigate the influence of troposcatter channel parameters on chaos synchronization and communication performance.
• To assess the feasibility of secure, long-distance wireless data transmission.

Main Methods:

• Utilizing parameter-matched semiconductor lasers for chaos synchronization induced by a common digital signal.
• Employing optoelectronic conversion and resampling to generate synchronous radio chaos.
• Propagating chaos-encrypted messages through a troposcatter channel for decryption.

Main Results:

• Demonstrated BLOS chaotic secure transmission of a quadrature phase-shift keying message over 50 km at 200 Mb/s.
• Achieved a bit error rate (BER) below the forward error correction threshold (3.8 × 10^-3).
• Identified transmission distance, SNR, and multipath number as key factors influencing synchronization and BER.

Conclusions:

• The proposed scheme enables secure BLOS chaotic communication via troposcatter.
• System performance is sensitive to multipath delay spread but robust to Doppler shift.
• The scheme holds promise for extending long-distance wireless chaos communication with enhanced physical-layer security.