Layered hybrid PAM-DMT for IM/DD OWC systems

Area of Science:

• Electrical Engineering
• Optical Communications
• Signal Processing

Background:

• Traditional pulse-amplitude-modulated discrete multitone modulation (PAM-DMT) exhibits limitations in spectral and power efficiencies for optical wireless communication (OWC).
• Existing schemes struggle to optimize performance in intensity modulation with direct detection (IM/DD) OWC systems.

Purpose of the Study:

• To introduce a novel modulation scheme, layered hybrid PAM-DMT (LHPAM-DMT), to enhance spectral and power efficiencies in OWC.
• To improve upon the performance limitations of conventional PAM-DMT and other popular OWC modulation techniques.

Main Methods:

• Dividing the frequency domain signal's real part into multiple layers.
• Incorporating symmetry biases in the time domain to ensure real-valued and nonnegative signals for IM/DD.
• Developing an iterative receiver that leverages signal orthogonality between layers for information recovery.

Main Results:

• LHPAM-DMT theoretically achieves higher spectral efficiency compared to standard PAM-DMT.
• The proposed scheme demonstrates lower computational complexity than layered PAM-DMT.
• Numerical simulations indicate superior power efficiency for LHPAM-DMT over both PAM-DMT and DC-biased optical OFDM (DCO-OFDM).

Conclusions:

• LHPAM-DMT presents a significant advancement for OWC systems, offering improved spectral and power efficiency.
• The proposed iterative receiver effectively recovers transmitted data while maintaining low complexity.
• LHPAM-DMT is a promising alternative to existing modulation schemes for future OWC applications.