Low-complexity equalizer with a hybrid decision scheme for 50  Gb/s/λ PAM4-PON using a low-cost 10 G receiver

Area of Science:

• Optical Communications
• Signal Processing
• Telecommunications Engineering

Background:

• Passive optical networks (PONs) are crucial for broadband access, but face challenges with increasing data rates and channel distortions.
• Existing equalization techniques like memory polynomial equalizer (MPE) and decision feedback equalizer (DFE) are used to mitigate these distortions.
• Improving receiver sensitivity and link power budget is essential for higher data rates in PON systems.

Purpose of the Study:

• To experimentally demonstrate a 50 Gb/s/λ four-level pulse amplitude modulation (PAM4)-based PON system.
• To propose and evaluate a low-complexity hybrid decision scheme (HDS) to enhance MPE-DFE performance.
• To improve receiver sensitivity and link power budget in high-speed PON systems.

Main Methods:

• Implementation of a 50 Gb/s/λ PAM4-based PON system utilizing a 10 G class receiver.
• Application of a memory polynomial equalizer (MPE) combined with a decision feedback equalizer (DFE).
• Introduction of a novel hybrid decision scheme (HDS) integrating single-symbol decision (SSD) and multi-symbol decision (MSD) for improved detection.

Main Results:

• The proposed MPE-DFE with HDS achieved significant sensitivity gains of 0.7 dB and 1.3 dB over conventional SSD.
• The system demonstrated substantial link power budgets of up to 35.4 dB and 31.4 dB at forward error correction thresholds of 10⁻² and 10⁻³, respectively.
• The MSD component of HDS, while slightly increasing multiplications (19.1%), processed less than 20% of the signal frame at received optical power > -27 dBm.

Conclusions:

• The novel hybrid decision scheme (HDS) effectively enhances the performance of MPE-DFE in high-speed PON systems.
• The proposed system achieves superior receiver sensitivity and extended link power budget, crucial for future optical network advancements.
• HDS offers a practical solution for improving data transmission in optical networks without significant complexity overhead.