Augmenting the spectral efficiency of enhanced PAM-DMT-based optical wireless communications

Area of Science:

• Optical Communications
• Digital Signal Processing
• Information Theory

Background:

• Pulse-amplitude-modulated discrete multitone modulation (PAM-DMT) faces energy efficiency challenges with increasing modulation orders.
• Enhanced PAM-DMT (ePAM-DMT) attempts to improve efficiency via superposition but suffers from complex alignment and losses.
• Existing methods like DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) have limitations.

Purpose of the Study:

• To introduce a novel, simplified method for superposition modulation on M-PAM modulated DMT.
• To enhance both spectral and energy efficiency in digital communication systems.
• To analyze the bit error rate (BER) performance of the proposed system.

Main Methods:

• Developed Augmented Spectral Efficiency Discrete Multitone (ASE-DMT) signal generation in the frequency domain.
• Derived the analytical bit error rate (BER) performance bound.
• Conducted Monte-Carlo simulations for performance validation.

Main Results:

• ASE-DMT achieves improved spectral and energy efficiency compared to PAM-DMT and ePAM-DMT.
• The frequency-domain signal generation simplifies the superposition process.
• Significant electrical and optical energy savings were demonstrated.

Conclusions:

• ASE-DMT offers a more efficient alternative to ePAM-DMT and DCO-OFDM.
• The proposed method overcomes the complexity and efficiency losses associated with time-domain superposition.
• ASE-DMT presents a promising approach for energy-efficient optical communication systems.