Spectrum-efficient hybrid PAM-DMT for intensity-modulated optical wireless communication.

Area of Science:

• Optical Wireless Communication (OWC)
• Signal Processing
• Modulation Techniques

Background:

• Superimposed optical orthogonal frequency division multiplexing (O-OFDM) enhances spectrum efficiency in OWC.
• Layered asymmetrically clipped O-OFDM (LACO-OFDM) improves spectrum efficiency but increases receiver complexity and latency.

Purpose of the Study:

• To propose a novel hybrid pulse-amplitude-modulated discrete multitone modulation (HPAM-DMT) architecture for spectrum-efficient OWC.
• To achieve high spectrum efficiency with reduced complexity and latency compared to existing methods.

Main Methods:

• Designing a PAM-DMT signal using real parts of subcarriers.
• Superimposing the designed PAM-DMT signal onto a classic PAM-DMT signal for simultaneous transmission.
• Utilizing a novel architecture for superimposed PAM-DMT signals.

Main Results:

• HPAM-DMT achieves the same spectrum efficiency as LACO-OFDM with significantly lower complexity and latency.
• Improved bit-error rate (BER) performance under transmitter nonlinearity compared to LACO-OFDM.
• Higher power efficiency than conventional O-OFDM schemes.

Conclusions:

• HPAM-DMT is a competitive scheme for intensity modulation/direct detection (IM/DD)-based OWC.
• The proposed architecture effectively balances spectrum efficiency, complexity, and latency.
• HPAM-DMT demonstrates superior performance, especially under nonlinear conditions.