Evaluation of the Impact of Different SDM Switching Strategies in a Network Planning Scenario

Rivas-Moscoso

Marom

et al. 2017

J. Lightwave Technol.

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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.

Section: Related Work and Novelty Of The Papermentioning

confidence: 93%

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

Rivas-Moscoso

Marom

et al. 2017

J. Lightwave Technol.

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“…Going back to SDM, several previous works (e.g., [3][4][5]18,19]) highlighted the need to realize flexibility/cost trade-offs in SDM ROADM designs, due to the extremely high cost of supporting fully flexible switching in both the spatial and spectral domains. Three different switching paradigms are described in the literature [3]: 1) independent switching (InS), in which demands can be switched freely in both spectrum and space, is the most flexible but also the most complex and expensive to realize, requiring a huge number of WSSs; 2) joint switching (JoS), where space is a degenerate dimension that is switched as a single spatial group (i.e., a certain piece of spectrum across all spatial dimensions in an input port is routed toward the same output port), is far simpler and cheaper to realize (it requires a single WSS per degree per direction, far less than InS [3,5]), but is also far less flexible, equivalent to having a single spatial dimension for routing purposes (i.e., it has a huge increase in minimum traffic granularity, equivalent to the number of jointly switched spatial dimensions); and 3) fractional-joint switching (FJoS) offers a middle ground between the other two options, by switching sub-groups of spatial dimensions (which we just call "spatial groups," plural, visually outlined in Fig.…”

Section: Sdm Switching Paradigms and Previous Workmentioning

confidence: 99%

“…Thus, for example, realizing a four-degree ROADM, with nine spatial dimensions, would require using WSSs with a minimum port count of 9 × 1 × 4, i.e., 45 ports. That said, the increase in unitary cost associated with higher port count WSSs would be counteracted by a significantly smaller number of WSSs required in the ROADM architecture [4]; in the aforementioned example, InS would require 72 1 × 3 WSSs, while JoS would need only eight, but of port count 9 × 27 [assuming a design without a dedicated add/drop (A/D) degree]. Taking into account that, historically, the cost per port of single-mode WSSs has been inversely proportional to the port count [20], we expect that telecom operators could derive substantial benefits by exploiting (F)JoS in a SDM network scenario.…”

Section: Sdm Switching Paradigms and Previous Workmentioning

confidence: 99%

“…Such a solution offers the greatest theoretical increase in network capacity without impacting flexibility, but the resulting cost makes it unattractive from a practical perspective. This cost increase can be mitigated by adopting the joint and fractional-joint switching paradigms (JoS and FJoS) proposed in [3], which allow significant cost savings while still achieving the same increments in maximum capacity, albeit at the cost of reduced flexibility [4] (which may prevent the exploitation of some of that additional capacity).…”

Section: Introductionmentioning

confidence: 99%

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Improving Performance of Spatially Joint-Switched Space Division Multiplexing Optical Networks via Spatial Group Sharing

Pederzolli

Siracusa

et al. 2017

J. Opt. Commun. Netw.

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Space division multiplexing (SDM) is a promising approach to overcome the looming fiber capacity crunch. Joint and fractional joint switching (JoS and FJoS) architectures, which switch multiple spatial dimensions together as atomic units, have been proposed to reduce the cost of implementing SDM and cater to strongly coupled transmission media. However, they have been shown to impose significant penalties to overall network performance, at least when many relatively small connections are used in the context of uncoupled spatial dimensions, while performing nearly as well as the independent switching (InS) architecture if the average connection size is sufficiently large to efficiently exploit their increased granularity. In this work we tackle the performance penalty that JoS and FJoS architectures impose on SDM networks with uncoupled spatial dimensions compared to InS, by proposing two novel routing, space, and spectrum allocation (RSSA) heuristics that effectively share jointly switched resources, adapted to use different types of SDM reconfigurable optical add/drop multiplexer architectures requiring only a small additional cost. We investigate the performance of these new RSSA algorithms compared to an existing one under several traffic conditions and models using simulations. We find that our proposals can achieve significant improvements in the performance of SDM networks carrying large numbers of relatively small connections, up to parity of performance with InS designs, at a lower implementation cost, under all traffic conditions under study, including different average connection sizes and size diversity.

“…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].…”

Section: Introductionmentioning

confidence: 99%

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

Savva

Ellinas

2018 IEEE International Conference on Communications (ICC)

et al. 2018

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In this work, efficient routing, spectrum, and core allocation (RSCA) techniques are proposed for spatial division multiplexed (SDM) elastic optical networks (EONs) utilizing multicore fibers (MCFs). These techniques provide efficient resource utilization with minimal computational complexity, while also taking into consideration physical layer effects. Initially, a crosstalk-aware approach is presented that accounts for the crosstalk effects in the network that can have detrimental impact on the connections established in the network. This approach is subsequently enhanced with a feedback-based procedure that takes into account all physical layer impairments, aiming to minimize the number of connections that cannot be established in the network due to quality-of-transmission (QoT) considerations.