Pilot-aided carrier phase recovery for M-QAM using superscalar parallelization based PLL

Area of Science:

• Optical Communications
• Digital Signal Processing
• Telecommunications Engineering

Background:

• Carrier phase recovery (CPR) is critical for high-speed optical communication systems.
• Existing CPR algorithms like Blind Phase Search (BPS) face limitations in performance and computational complexity.
• The need for efficient CPR algorithms that balance performance and resource utilization is paramount.

Purpose of the Study:

• To introduce a novel CPR algorithm, M-SSP-PLL + ML, for improved optical data transmission.
• To demonstrate the enhanced performance and reduced complexity of the proposed M-SSP-PLL + ML algorithm.
• To compare the M-SSP-PLL + ML algorithm against established methods like BPS in terms of performance and resource efficiency.

Main Methods:

• Development of a modified superscalar parallelization based phase locked loop (M-SSP-PLL).
• Integration of maximum-likelihood (ML) phase estimation with the M-SSP-PLL.
• Reduction of buffer size through a novel superscalar structure and elimination of differential coding/decoding.
• Performance evaluation through simulations and experimental tests using QPSK, 16-QAM, and 64-QAM formats.

Main Results:

• The M-SSP-PLL + ML algorithm achieves a reduced buffer size compared to the original SSP-PLL.
• Experimental results show M-SSP-PLL + ML increases transmission distance by at least 12% over BPS for various QAM formats.
• The laser linewidth tolerance of M-SSP-PLL + ML is comparable to the BPS algorithm.
• A significant reduction in computational complexity is achieved by M-SSP-PLL + ML relative to BPS.

Conclusions:

• The M-SSP-PLL + ML algorithm offers superior performance in terms of transmission distance and efficiency for optical communication systems.
• This novel CPR approach provides a competitive alternative to existing methods like BPS, especially in demanding high-baudrate scenarios.
• The algorithm's reduced complexity and enhanced performance make it a promising solution for next-generation optical networks.