This letter extends the decision-aided (DA) maximum likelihood (ML) phase estimation in an Mary phase-shift keying (PSK) system to quadrature amplitude modulation (QAM) signals. The block length effect is simulated for both M-ary PSK and QAM systems, and also investigated in M-ary PSK systems through analysis. Our results show that the tolerance of DA ML to laser linewidth for square 16-QAM can be increased by >10 times compared to the block Mth power scheme.
- Coherent detection
- Optical fiber communication
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Electrical and Electronic Engineering