Impact of Spatial and Spectral Granularity on the Performance of SDM Networks Based on Spatial Superchannel Switching

Abstract

Spatially integrated switching architectures have been recently investigated in an attempt to provide switching capability for networks based on spatial division multiplexing (SDM) fibers, as well as to reduce the implementation cost. These architectures rely on the following switching paradigms, furnishing different degrees of spectral and spatial switching granularity: independent switching (Ind-Sw), which offers full spatial-spectral flexibility; joint-switching (J-Sw), which treats all spatial modes as a single entity; and fractional-joint switching (FrJ-Sw), whereby subgroups of spatial modes are switched together as independent units. The last two paradigms are categorized as spatial group switching (SG-Sw) solutions since the spatial resources (modes, cores, or single-mode fibers) are switched in groups. In this paper, we compare the performance (in terms of spectral utilization, data occupancy, and network switching infrastructure cost) of the SDM switching paradigms listed above for varying spatial and spectral switching granularities in a network planning scenario. The spatial granularity is related to the grouping of the spatial resources, whereas the spectral granularity depends on the channel baud rate and the spectral resolution supported by wavelength selective switches (WSS). We consider two WSS technologies for handling of the SDM switching paradigms: 1) the current WSS realization, 2) WSS technology with a factor-two resolution improvement. Bundles of single-mode fibers are assumed across all links as a near-term SDM solution. Results show that the performance of all switching paradigms converge as the size of the traffic demands increases, but finer spatial and spectral granularity can lead to significant performance improvement for small traffic demands. Additionally, we demonstrate that spectral switching granularity must be adaptable with respect to the size of the traffic in order to have a globally optimum spectrum utilization in an SDM network. Finally, we calculate the number of required WSSs and their port count for each of the switching architectures under evaluation, and estimate the switching-related cost of an SDM network, assuming the current WSS realization as well as the improved resolution WSS technology.

Network Performance Trade-Off in Modular Data Centers With Optical Spatial Division Multiplexing

“…The first scheme (A1) is referred to as uncoupled SDM with flexible-grid WDM. This architecture requries one conventional spectrum selective switch (SSS) and one spatial mux/demux per spatial element for each transmission direction of the SDM fiber [21], [22]. Flexible-grid and tunable transceivers are deployed inside the PODs to transmit/receive spectral superchannels [6].…”

All-Optical VCSEL-to-VCSEL Injection Based on Cross Gain Modulation for Routing in Multinode Flexible Spectrum Optimization in Optical Fibre Transmission Links

“…In the past, the DWDM optical network promised to be a solution for the traffic growth: dividing the available transmission bandwidth of an optical fibre into nonoverlapping wavelengths with a fixed grid spectrum channel spacing typically ITU-T 50 or 100 GHz [1]. ese networks offer the possibility to establish wavelength connections at a fixed bit rate, i.e., 10,40, and recently 100 Gb/s at 50 GHz channel spacing [2]. e bandwidth request of today's network end user requires more customized services and more differentiated demands with different prices [3].…”

“…is push in the transmission rates of a single optical carrier brings the limit for transmission over any meaningful reach. Other advantages of flexible spectrum networks include reconfigurable nodes, bandwidth-variable transmitters, adjustable wavelength and spectrum allocation, and the centralized network management [9,10].…”

Physical Layer-Aware Routing, Spectrum, and Core Allocation in Spectrally-Spatially Flexible Optical Networks with Multicore Fibers

“…In SS-FONs, there are generally three mechanisms for switching from one core to another, which are highly correlated with the different types of fibers introduced for SDM networks [4]; independent switching (Ind-Sw), where all cores can be independently directed to any other core, joint switching (J-Sw), where each core can switch to only one core, and fractional joint switching (Fr J-Sw), a hybrid approach where a group of cores can be directed to another specific group of cores. Each switching mechanism offers benefits and drawbacks regarding performance, flexibility, and hardware cost as described in detail in [5].…”