Time-reversal waveform design for underwater wireless optical communication systems.

Area of Science:

• Optical Communications
• Signal Processing

Background:

• Underwater wireless optical communications (UWOC) face challenges like scattering, absorption, and turbulence, hindering reliable data transmission.
• The dispersive nature of UWOC channels, caused by multipath effects from scattered photons, leads to intersymbol interference (ISI).

Purpose of the Study:

• To propose and evaluate a time-reversal (TR) waveform design technique for UWOC systems.
• To mitigate intersymbol interference (ISI) and enhance the reliability of underwater optical communication.

Main Methods:

• Deriving the UWOC channel model considering exponential bias and random scattering effects for intensity modulation and direct detection systems.
• Analyzing and simulating the performance of a proposed time-reversal (TR) waveform in UWOC channels.
• Investigating the 'squeezing effect' impacting TR waveform design in non-negative UWOC channels.

Main Results:

• The time-reversal (TR) waveform is well-suited for UWOC systems, creating a symmetric equivalent channel that simplifies equalization.
• A 'squeezing effect' was identified, necessitating the application of an equalizer for optimal TR waveform performance.
• The use of TR waveforms resulted in a significantly improved bit error rate compared to systems without TR waveforms.

Conclusions:

• Time-reversal (TR) waveform design is an effective technique for reducing intersymbol interference (ISI) in underwater wireless optical communications (UWOC).
• The identified 'squeezing effect' highlights the importance of equalization in UWOC systems employing TR waveforms.
• TR waveform implementation substantially enhances data transmission reliability and reduces bit error rates in challenging underwater environments.