Low-complexity carrier phase recovery based on principal component analysis for square-QAM modulation formats

Area of Science:

• Optical communications
• Signal processing
• Digital communications

Background:

• Carrier phase recovery (CPR) is crucial for coherent optical receivers.
• Existing methods like Blind Phase Search (BPS) can be complex and struggle at low SNRs.
• Modulation-order independence and hardware suitability are key challenges.

Purpose of the Study:

• To propose and validate a novel, low-complexity, modulation-order independent, non-data-aided (NDA) feed-forward CPR algorithm.
• To enable synchronous decoding of arbitrary square-quadrature amplitude modulation (QAM) constellations.
• To offer a hardware-friendly solution for realistic implementations.

Main Methods:

• The core method utilizes Principal Component Analysis (PCA) for feed-forward CPR.
• A hybrid two-stage approach combining PCA and BPS is also investigated.
• Numerical simulations and experimental demonstrations are employed for analysis.

Main Results:

• The proposed PCA-based algorithm outperforms BPS at low SNR, exhibiting a significantly lower cycle slip rate (CSR).
• The hybrid PCA-BPS method shows competitive performance.
• Significant computational complexity savings of 92% (simple) and 40% (hybrid) are achieved compared to two-stage BPS (2S-BPS).

Conclusions:

• The proposed PCA-based NDA-CPR algorithm offers a low-complexity and effective solution for optical communications.
• It demonstrates superior performance at low SNR and reduced computational load.
• The algorithm is suitable for practical hardware implementation, enhancing system efficiency.