Low-complexity carrier phase estimation algorithms for space coherent optical communication

This paper proposes a high linewidth tolerance and low-complexity carrier phase estimation (CPE) algorithm for 16QAM, which avoids complex fourth-power operations compared to traditional Viterbi algorithms based on QPSK partitioning, significantly reducing hardware complexity. Simulation results indicate that this algorithm performs comparably to the Viterbi-Viterbi (V-V) algorithm based on QPSK partitioning in terms of phase noise linewidth tolerance, OSNR performance, and estimation accuracy. Additionally, this paper proposes a two-stage CPE algorithm. The first stage employs the proposed low-complexity phase-based estimation method for coarse estimation, while the second stage enhances estimation accuracy further through an optimized error function, utilizing its relationship with phase estimation errors. Simulation results show that this algorithm exhibits linewidth tolerance performance similar to the Blind Phase Search (BPS) algorithm and possesses good resistance to atmospheric turbulence. Compared to the BPS algorithm, the hardware resource consumption is reduced by 8 times and 5 times, significantly lowering hardware complexity.