Flexible Coherent PON for 6G Fixed Networks: Technologies and Solutions

The forthcoming sixth-generation fixed (F6G) network promises substantial advancements in capacity, connectivity, and latency. Owing to the high receiver sensitivity and spectral efficiency, flexible coherent passive optical networks (PON) offer the potential to significantly increase access performance, delivering enhanced capacity, expanded connectivity, and reduced latency for the evolution to the F6G network. The flexible coherent PON will apply several emergent technologies, including coherent optics technology, flexible multiple access, and flexible-rate technology. As an important application scenario of the flexible coherent PON, coherent point-to-multipoint (P2MP) optical aggregation can potentially replace point-to-point electrical aggregation for the F6G network, which enables the flexible upgrade and has low operational and capital expenditure. Based on the coherent P2MP optical aggregation, we demonstrate flexible multiple access of joint frequency-division multiple access and time-division multiple access (TDMA) cooperating with flexible-rate technology to balance capacity, connectivity, and latency. Meanwhile, burst-mode digital signal processing is proposed for the TDMA burst signal in the flexible multiple access. In summary, the flexible coherent PON is poised to make significant contributions to the future F6G network.