Multilevel polarization shift keying modulation for turbulence-robust underwater optical wireless communication

Area of Science:

• Optical communication
• Fluid dynamics
• Signal processing

Background:

• Turbulence poses a significant challenge for underwater optical wireless communication (UOWC).
• Existing research primarily focuses on modeling and performance analysis, with limited experimental work on turbulence mitigation.
• Intensity-based modulation schemes struggle with optimal thresholding in turbulent UOWC channels.

Purpose of the Study:

• To experimentally investigate the effectiveness of multilevel polarization shift keying (PolSK) for mitigating turbulence effects in UOWC.
• To compare the performance of PolSK with traditional intensity-based modulation schemes under turbulent conditions.
• To analyze the impact of transmitted optical power on system performance.

Main Methods:

• Establishment of a 15-meter-long water tank experimental setup for UOWC.
• Implementation of a multilevel PolSK modulation scheme.
• Investigation of system performance under temperature gradient-induced turbulence and varying optical powers.

Main Results:

• PolSK modulation demonstrates feasibility in alleviating turbulence effects in UOWC.
• The PolSK system achieved significantly better bit error rate performance than intensity-based schemes.
• Experimental validation of PolSK's robustness in challenging underwater optical channels.

Conclusions:

• Multilevel PolSK is a viable and effective modulation technique for overcoming turbulence in UOWC.
• PolSK offers a practical solution for improving the reliability of underwater optical communication systems.
• This experimental study provides valuable insights for the advancement of UOWC technologies.