Chris Matrakidis

IST-DAVID: concept presentation and physical layer modeling of the metropolitan area network

The data and voice integration over dense-wavelength-division multiplexing (DAVID) metropolitan area network (MAN), following the packet-over-wavelength-division-multiplexing (WDM) approach, introduces a fast, agile, dynamically reconfigurable, and service-transparent optical layer. The fast reconfiguration allows the implementation of statistical multiplexing purely in the optical domain. Scalability limitations in the MAN network are attributed to noise accumulation, crosstalk, spectral narrowing from long cascades of multiplexers/demultiplexers, and fiber nonlinearities. Physical layer studies carried out using both analytical modeling and a commercial simulation tool show that the predominant source of Q degradation is spectral narrowing. It is shown that considering the longest protection path, a DAVID MAN network offering a 1.5-Tb/s capacity is feasible.

An Optical Network Architecture With Distributed Switching Inside Node Clusters Features Improved Loss, Efficiency, and Cost

The novel core network architecture presented in this paper realizes distributed all-optical switching of payload by partitioning the network into a number of geographically limited domains, where two-way reservations are effective. Thus, inside each domain, loss is eliminated, while traffic from many nodes can be aggregated into single bursts, improving efficiency. Clustered nodes contribute contiguous optical slots, which are marshaled into composite optical frames destined for other clusters, under the guidance of a reservation-based control protocol. The lossless aggregation of traffic from several core nodes allows the use of cost-effective bufferless all-optical transport among the domains with electrical buffers employed at the periphery of the system. The end result is a triple improvement in loss probabilities, efficiency, and cost. This is achieved by exploiting three features of the architecture: the distributed switching functionality (as in early LANs when centralized switching was expensive), localized reservations (avoiding the intolerable delays of end-to-end reservations), and a reduced number of source-destination pairs (by means of node clustering into reservation domains)

Cross Layer Routing in Transparent Optical Networks

New algorithmically simplified WRA that incorporate physical layer criteria in the path establishment procedure are suggested and applied in the Deutsche-Telecom network. Their blocking performance superiority and physical performance guarantee are discussed.

Optical Wavelength and Waveband Converters

Wavelength conversion has been acknowledged as one of the most significant optical processing functions and various papers have been involved with investigating methods of translating very high bit-rate data into other wavelengths. This paper will give an overview of the recent advances in the area, with emphasis on methods that can be used as both wavelength and waveband converters, which can be used at higher bit rates without any configuration changes and are integratable and hence compact solutions. Four-wave mixing in SOAs is one of these techniques and we will elaborate on particulars of this technique. Switch architectures that benefit from wavelength and waveband conversion are presented

Simplified model for nonlinear noise calculation in coherent optical OFDM systems

A simplified closed form expression for the noise power due to four-wave mixing in coherent OFDM systems is derived. The proposed model is in very good agreement with the exact model. The derived analytical expressions can be used in performance evaluation of systems employing CO-OFDM with any number of subcarriers and/or as an integral part of physical layer aware routing algorithms.

Electronic dispersion compensation of fiber links using sparsity induced volterra equalizers

During the last few years, a lot of research has been invested for the development of electronic devices equipped with advanced signal processing techniques for the dispersion compensation of Optical transmission systems. Compared to their all-optical counterparts, electronic compensation increases flexibility and gives a new impetus to transparent optical networks for adaptive and dynamic handling in cases where the total accumulated dispersion is not known in advance. In this paper, the Sparse Learning via Iterative Minimization (SLIM) algorithm is employed for the design of reduced size Volterra Decision Feedback (VDFE) equalizers in the context of optical communications is considered. The equalizer structure is dynamically tuned discarding coefficients that have a marginal contribution to the performance of the equalizer leading to both enhanced convergence speed and significant computational complexity savings.

HYDRA: A Scalable Ultra Long Reach/High Capacity Access Network Architecture Featuring Lower Cost and Power Consumption

This paper proposes HYbriD long-Reach fiber Access network (HYDRA), a novel network architecture that overcomes many limitations of the current WDM/TDM PON approaches leading to significantly improved cost and power consumption figures. The key concept is the introduction of an active remote node that interfaces to end-users by means of the lowest cost/power consumption technology (short-range xPON, wireless, etc.) while on the core network side it employs adaptive ultra-long reach links to bypass the metropolitan area network. The scheme leads to a higher degree of node consolidation and access-core integration. We demonstrate that HYDRA can achieve very high performance based on mature component technologies ensuring very low cost end-user terminals, reduced complexity, and high scalability.

Next generation optical network architecture featuring distributed aggregation, network processing and information routing

The ontology of communications is rapidly changing, shifting interest to machine-to-machine (M2M) interactions and the internet of Things (IoT). These are becoming vital for sustainability of social life and the revitalization of the economy providing the infrastructure to new production forms like distributed manufacturing, cloud robotics while becoming important to grid-based energy systems. Adding to them the voracious needs for data of the traditional broadband users, residential or business, together with the back/front hauling requirements of mobile operators, one is expecting a significant strain in the access. A multitude of heterogeneous access networks are emerging and the integration of them in a single platform ensuring seamless data-exchange with Data-Centres is of major importance. In this paper we describe HYDRA (HYbriD long-Reach fiber Access network), a novel network architecture that overcomes the limitations of both long-reach PONs as well as mobile backhauling schemes, leading to significantly improved cost and power consumption figures. The key concept is the introduction of an Active Remote Node (ARN) that interfaces to end-users by means of the lowest cost/power consumption technology (short-range xPON, wireless, etc.) whilst on the core network side it employs adaptive ultra-long reach links to bypass the Metropolitan Area Network. The scheme leads to a higher degree of node consolidation, network convergence and Access-Core integration. The proposed architecture can enhance performance while supporting network virtualization and efficient resource orchestration based on Software Defined Networking (SDN) principles and open access networking models.

Routing in dynamic future flexi-grid optical networks

Routing in dynamic future optical networks will depend on the underlying technology and more specifically on whether standard grid or flexi-grid technology will be used. In particular for dynamic flexi-grid networks resource allocation and routing concerns both path establishment and allocation of specific spectrum which in turn relates to the modulation format of the transmitted signals. Moreover if variable bandwidth transponders are utilized simultaneous optimization of allocated spectrum and transponder reach should be performed. In this paper we investigate the benefits of flexi-grid technology with variable bandwidth transponders regarding blocking performance and spectral efficiency when compared to the standard-grid counterpart.

A Hybrid Optical Switch Architecture with Shared Electronic Buffers

In this paper we present a hybrid opto-electronic switch architecture, which can be enhance the performance of optical packet switching (OPS) schemes. The proposed architecture is based on the use of electronic line-cards and packet cross-connect to a limited degree utilizing the large buffering capacity available only by means of electronic subsystems. This hybrid architecture achieves efficient utilization of optical network resources, which can be assigned dynamically in small time scales, limiting loss probability with controlled average latency.