Digital Subcarrier Multiplexing: Enabling Software-Configurable Optical Networks

Abstract

The various topologies, traffic patterns and cost targets of optical networks have prevented the deployment of endto-end solutions across multi-domains, and the optimization of the network as a whole. The consequent limitations in flexibility, scalability, and adaptability of optical networks will become increasingly important with new applications, such as 5G/6G. Coherent transceivers based on digital subcarrier multiplexing (DSCM) are proposed to address these current constraints. In particular, DSCM allows (i) the design of high-capacity pointto-point (P2P) and -multipoint (P2MP) optical networks; (ii) simplified aggregation with passive optics; and (iii) connections between low-and high-speed transceivers. Furthermore, DSCMbased networks reduce the number of opto-electro-opto stages, halve the number of bookended transceivers, and provide a better match for existing hub-and-spoke (H&S) traffic patterns in fast-growing and dynamic access/metro segments. A DSCMbased transceiver will pave the way for the deployment of nextgeneration flexible, adaptable, and scalable software-configurable optical networks.Key steps and elements to realize this solution are laid out, and promising applications outlined. The first real-time experimental results of coherent P2MP transceivers are presented.

End-to-End Optimization of Constellation Shaping for Wiener Phase Noise Channels With a Differentiable Blind Phase Search

“…In each batch of every epoch, the input bits are randomly permuted and a new noise realization is used. While a symbol rate of 32 GBaud is quite low for modern single-carrier transmission systems, it is a realistic value for multi-carrier transmission systems [28]- [30]. Additionally, for low cost systems where coherent transmission is relevant, the symbol rate may be higher, but the resulting phase noise is still comparable to our parameterization due to low cost and high linewidth lasers [31].…”

Point-to-Multi-Point Coherent Optics on Data Processing Units (DPUs) for beyond-5G Low-Latency Applications

“…2. Considering that subcarriers could have different levels of distortions (both linear and non-linear), the robustness and effectiveness of the DSP algorithms is a non-trivial aspect of the design of the P2MP transceiver [9].…”

Point-to-multipoint Coherent Transceivers for Next-Generation Mobile Transport

“…In Fig. 2, we assume leaf node transceivers capable of transmitting up to 100G (4×25G) at 4 GBaud using 16 Quadrature Amplitude Modulation (16-QAM) and dual polarization; while the hub node operates at the same conditions, but can use up to 16 digital subcarriers [11,19] for a total of 400G (16×25G). As the subcarriers are generated in the digital domain, only one laser is needed.…”