PCS-16QAM vs QPSK: What is the best choice for Next-Generation Long-Haul 400G? - Abel Lorences-Riesgo; Djalal-Falih Bendimerad; K. Le-Trung; Ivan Fernandez de Jauregui Ruiz; Yu Zhao; Martí Sales-Llopis; S. Kamel; K. Huang; Celestino Sanches Martins; Dylan Le Gac; Sami Mumtaz; Stefanos Dris; et al. (ECOC, 2021)