Two-level coding for efficient digital radio-over-fiber transmission with unequal bit protection

Area of Science:

• Optical Communications
• Digital Signal Processing
• Fiber Optic Transmission

Background:

• Digital radio-over-fiber (D-RoF) systems are crucial for high-speed data transmission.
• Efficient coding schemes are needed to balance performance and complexity in D-RoF.

Purpose of the Study:

• To propose and demonstrate a novel two-level coding (TLC) scheme for D-RoF systems.
• To jointly optimize quantization bits, forward error correction (FEC), and quadrature amplitude modulation (QAM) symbol reliability.

Main Methods:

• Implemented a TLC scheme where more significant bits receive FEC protection and are mapped to less reliable QAM bits.
• Less significant bits, without FEC, are mapped to more reliable QAM bits.
• Conducted experiments over an 11-km standard single-mode fiber link.

Main Results:

• The TLC-based D-RoF system achieved performance comparable to conventional bit-interleaved coded modulation (BICM).
• Achieved complexity reductions of 54.55% for 16QAM and 67.66% for 64QAM.
• Performance was evaluated under a 0.34% error vector magnitude threshold for 65536QAM signals.

Conclusions:

• TLC offers a viable and efficient approach for D-RoF systems.
• The proposed scheme effectively reduces computational complexity without significant performance degradation.
• This method is suitable for advanced modulation formats in optical transmission.