Bogdan Uscumlic

Optimal dimensioning of the WDM unidirectional ECOFRAME optical packet ring

To efficiently support the high rate and the high dynamicity of the traffic in metro networks, an optical packet-switched WDM ring, named ECOFRAME, is proposed. The key features of the proposed ring are optical transparency and statistical multiplexing of optical packets on parallel WDM channels. Such features can be exploited by properly allocating wavelengths and receivers. This paper aims to optimally dimension the unidirectional ECOFRAME rings. The dimensioning at minimum cost (i.e., for wavelengths and receivers) is modeled with an mixed-integer linear programming formulation. An heuristic algorithm is also proposed, and its performance is compared against the optimal solutions and bounds. When considering the receiver and wavelength cost, results indicate that trading the wavelengths for receivers allows cost saving of up to 75% with respect to WDM optical packet rings with a single dedicated wavelength per node (i.e., single receiver at each node).

Dimensioning and Energy Efficiency of Multi-Rate Metro Rings

Due to the ever-growing network capacity demand, energy-efficient and scalable networking solutions are needed in all networking segments. This paper focuses on the metro segment and compares the power consumption for four different technologies: Ethernet, Reconfigurable Optical Add-Drop Multiplexers (ROADM), Optical Transport Networks (OTN), and an optical packet switching (OPS) solution called Packet Optical Add-Drop Multiplexers (“POADM”), which was recently proposed. A novel resource allocation strategy for POADM-based OPS multi-rate rings is proposed for the first time. The multi-rate POADM ring network resource allocation problem is shown to be NP-hard and solved using both an MILP formulation and a heuristic. The MILP formulation and the heuristic are compared, along with dimensioning results for Ethernet and ROADM/OTN ring networks. Results show that multi-rate POADM rings achieve savings up to 10% with respect to single-rate design and can be enabled by assigning a different rate to each wavelength. Furthermore, POADM rings can be up to 5 times more energy-efficient than Ethernet rings and 30% than ROADM rings, assuming similar network efficiencies.

The impact of network design on packet scheduling in slotted WDM packet rings

The paper compares four architectural designs for packet-OADM-based unidirectional WDM rings, in terms of design cost and scheduling complexity. The tradeoffs between design cost and scheduling complexity are analyzed.

Submarine Transmission Systems Using Digital Nonlinear Compensation and Adaptive Rate Forward Error Correction

We report on a full C + L-band erbium-doped fiber amplified (EDFA) submarine transmission experiment of 178 wavelength-division multiplexed channels of 49-GBd polarization multiplexed 16QAM signals, achieving 54.2 Tb/s after 6600 km, with a record per-channel average net bit rate of 304.5 Gb/s. Digital backpropagation and time-domain perturbative nonlinearity compensation were alternatively applied to all channels and their respective benefits, in terms of throughput increase, reach increase, and complexity, were addressed. Multiple-rate spatially coupled low density parity check forward error correction codes with a novel rate optimization algorithm were employed. The power consumption of the power feeding equipment of our EDFA-only amplification scheme was analyzed and compared with that of hybrid EDFA Raman amplification. We also provided numerical and theoretical performance analysis of nonlinear uncompensated/compensated systems.

A cost comparison of survivable subwavelength switching optical metro networks

In this paper, we compare the cost of the survivable optical transport solutions with subwavelength switching granularity. The focus is on Time-Domain Wavelength Interleaved Network (TWIN) and Packet Optical Add/Drop Multiplexer (POADM) network. Both technologies exploit optical slot switching: TWIN on a physical mesh topology, and POADM on a physical ring. The cost model accounts for the node components, the transponder cost and the cost of wavelength use per km of fiber. For the first time, a single network dimensioning model supporting protection is proposed for these metro technologies. The network planning solution is based on linear programming, and addresses the routing and wavelength assignment problem (RWA) and the optimal scheduler calculation. We consider dedicated protection, which consist in doubling the capacity of each operational connection network and shared protection, in which the protection capacity is potentially shared between multiple backup flows. By running the linear programming optimization we study the impact of different protection models on the cost of networks in different configurations and identify the scenarios for which each of the technologies is best suited.

Green optical slot switching torus for mega-datacenters

We propose a torus topology to interconnect Optical Slot Switching rings using elastic-rate transponders. Power consumption in mega-datacenters can be reduced by more than 3x and interfaces and cables by more than 500x when compared with the traditional Ethernet architecture.

54.2 Tb/s transoceanic transmission using ultra low loss fiber, multi-rate FEC and digital nonlinear mitigation

We demonstrate 54.2Tb/s transmission over transoceanic distances with an average channel rate above 300Gb/s and power consumption as low as 37.1pW/bit/s for the transmission line, thanks to ultra-low-loss fibers, multi-rate FECs and digital nonlinear mitigation techniques.

Full featured and lightweight control for optical packet metro networks [Invited]

Metro networks support increasing traffic volumes and evolving traffic profiles. Revisiting metro network architecture, optical packet rings with packet optical add and drop multiplexing (POADM) features are proposed in order to support both optical transparency and subwavelength granularity. A medium access control (MAC) structure for multiring POADM networks is proposed, which can support multiprotocol encapsulation and provides the support of differentiated quality of service (QoS) and differentiated protection on a per-flow basis. Unicast and multicast flows are efficiently transported between stations, with a lightweight control within each station. An opportunistic insertion process associated with an appropriate scheduling process is shown to ensure transport network QoS levels. Simple models are provided to assess the transfer performance on the POADM ring. Per-flow protection mechanisms are proposed, and their efficiency is assessed. Dimensioning costs are derived, which take into account the number of used wavelengths and the number of fixed receivers required to support a given traffic matrix. Finally, it is shown that POADM rings can be used to directly support metro Ethernet services and thus allow collapsing the stack of transport network layers.

Scalable routing, scheduling and virtualization for TWIN optical burst switching networks

We propose a comprehensive scalable algorithm simultaneously assessing the routing, scheduling and virtualization in Time-Domain Wavelength Interleaved Network (TWIN). TWIN is an energy-efficient optical burst switching technology for metropolitan area and data center intra- and interconnections, with destinations using separate allocated sets of wavelengths for the reception. Given the costs of the optical transponders and the wavelength use per km of fiber length, the proposed algorithm solves the routing and wavelength assignment problem, and in the same time allocates the time slots to traffic flows (performs the slot scheduling), so that the total network cost is minimized. The algorithm also enables the construction of overlayed virtual networking domains at minimum cost, which share the transponders and network links, and can employ different scheduling policies. The performance of the algorithm is compared with the pre-existing optimal dimensioning solution for single virtualization domain based on Integer Linear Programing, for different scenarios. The obtained results show that the network cost is within 27% of the optimal.

Cost of protection in Time-Domain Wavelength Interleaved Networks

In this paper, we study the cost of protection in Time-Domain Wavelength Interleaved Network (TWIN), an optical burst switching technology for transport networks with active edge nodes, passive core nodes, and time slotted operation. For the first time, an optimal network dimensioning with protection is proposed for TWIN, allowing to allocate the needed resources for dedicated and shared path protection. The dimensioning model is in the form of a 0-1 Integer Linear Program (0-1 ILP), and addresses both the routing and wavelength assignment problem, and the scheduler calculation. The cost of protection is studied for centralized and distributed traffic models, and it is shown that the shared path protection in TWIN is the most cost efficient.