Integrated THz/FSO Communications: A Review of Practical Constraints, Applications and Challenges

Area of Science:

• Wireless Communication
• Optical Communication
• Network Engineering

Background:

• Future networks like 6G and space-air-ground integrated networks (SAGIN) require high-capacity, long-distance, and ultra-reliable data transmission.
• Terahertz (THz) and Free-Space Optical (FSO) communication systems are key candidates for meeting these demands due to their complementary strengths.

Purpose of the Study:

• To provide a comprehensive review of integrated THz and FSO communication systems.
• To analyze advancements in channel modeling, transmission performance, and system architectures for these hybrid networks.
• To identify challenges and future research directions for robust integrated communication infrastructures.

Main Methods:

• Systematic review of recent advancements in THz and FSO communication.
• Analysis of channel characteristics, including attenuation, turbulence, pointing errors, and noise.
• Comparison of THz and FSO performance under various atmospheric conditions.
• Evaluation of integrated system architectures and adaptive switching strategies.

Main Results:

• THz communication offers Tbps rates over kilometers but is limited by molecular absorption and weather.
• FSO provides high bandwidth but suffers from turbulence-induced fading, impacting reliability.
• Integrated THz-FSO systems with adaptive switching demonstrate enhanced reliability and spectral efficiency, achieving seamless Tbps data rates.
• Persistent challenges include hardware integration, algorithmic optimization, and resource allocation.

Conclusions:

• Integration of THz and FSO technologies is crucial for future high-capacity, reliable communication networks.
• Further research is needed in unified channel modeling, shared architectures, and intelligent switching algorithms.
• Developing robust integrated communication infrastructures is essential for 6G and SAGIN deployments.