One symbol training receiver for the SPAD-based UVLC system.

Area of Science:

• Optical Communications
• Photonics
• Signal Processing

Background:

• Long-distance underwater visible light communication (UVLC) systems using single photon avalanche diodes (SPADs) face challenges with error floors and channel estimation.
• Existing multiple-symbol union detection schemes exhibit an irreducible bit-error ratio (BER) floor, limiting performance.

Purpose of the Study:

• To address the error floor and channel estimation issues in long-distance SPAD-based UVLC systems.
• To develop novel detection receivers that enhance the reliability and performance of UVLC.

Main Methods:

• Proposed a one training symbol maximum likelihood (ML) detection receiver by adding a training symbol to each frame.
• Developed a training ML detection (TMLD) receiver.
• Introduced a training modified (TM) quasi-ML receiver incorporating Anscombe root transformation for improved performance.

Main Results:

• The addition of a training symbol effectively eliminates the error floor in the BER curve.
• The proposed TMLD and TM quasi-ML receivers significantly enhance error-rate performance compared to traditional mean detection schemes.
• Reliable blind estimation of the long-distance UVLC channel is achieved.

Conclusions:

• The novel training symbol-based detection schemes offer a viable solution for overcoming limitations in long-distance SPAD-based UVLC systems.
• The proposed receivers demonstrate superior performance, paving the way for more robust underwater optical communication.