FPGA implementation for 44.2368-Gbit/s PAM8 signal transmission with pruned pre-equalization
Optics Letters
|September 1, 2023
Summary
This study showcases an intensity modulation and direct-detection system using FPGA technology. It successfully transmitted PAM8 signals at 44.2368 Gbit/s over 45-km SSMF, meeting SD-FEC criteria without optical amplifiers.
Area of Science:
- Optical Communications
- Digital Signal Processing
- Fiber Optic Systems
Background:
- Intensity Modulation and Direct-Detection (IM/DD) systems are crucial for high-speed optical communication.
- Field-Programmable Gate Arrays (FPGAs) offer flexible and high-performance solutions for signal processing in these systems.
- Achieving high data rates over standard single-mode fiber (SSMF) without optical amplification presents a significant challenge.
Purpose of the Study:
- To demonstrate a novel IM/DD system implemented on an FPGA.
- To evaluate the system's performance in transmitting high-order Pulse Amplitude Modulation (PAM8) signals over extended fiber lengths.
- To analyze the effectiveness of equalization algorithms for improving signal integrity and achieving target error correction thresholds.
Main Methods:
- Development of an IM/DD system utilizing an FPGA for signal processing.
- Transmission of PAM8 signals at a gross data rate of 44.2368 Gbit/s over 45-km SSMF.
- Implementation of a pruned pre-equalization algorithm at the transmitter.
- Application of parallel Constant Modulus Algorithm (CMA) and Decision-Directed Least Mean Square (DD-LMS) equalizers at the receiver.
- Analysis of Bit Error Rate (BER) performance through FPGA simulation.
Main Results:
- Successful transmission of PAM8 signals at 44.2368 Gbit/s over 45-km SSMF.
- Achievement of the Soft-Decision Forward Error Correction (SD-FEC) criterion (2.4 × 10-2).
- Demonstration of a net bit rate of 36.864 Gbit/s achievable without optical amplifiers.
- Analysis of BER performance variations with different data lengths before and after DD-LMS equalization.
Conclusions:
- The FPGA-based IM/DD system effectively supports high-speed PAM8 signal transmission over SSMF.
- The implemented equalization techniques are vital for meeting stringent SD-FEC requirements.
- The system's ability to operate without optical amplifiers signifies a potential for cost-effective and power-efficient optical communication solutions.
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