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164 JOURNAL OF NETWORKS, VOL. 5, NO. 2, FEBRUARY 2010 [9] A. J. Viterbi and A. M. Viterbi: "Nonlinear estimation of PSK-modulated carrier phase with application to burst digital transmission", IEE Transaction on Information Theory, Vol. 29, No. 4, 1983 [10] E. IP et al.: Coherent detection in optical fiber systems, OSA Optics Express, Vol. 16, No. 2, 2008 [11] E.Ip, J.M. Kahn: Digital equalization of chromatic dispersion and polarization mode dispersion, Journal of Lightwave Technology, Vol. 25, No. 8, August 2007, pp 2033-2043 [12] R. A. Griffin, A. C. Carter: Optical differential quadrature phase-shift key (oDQPSK) for high capacity optical transmission, OFC 2002, paper WX6 [13] [14] E. Ip, J.M. Kahn: Feedforward carrier recovery for coherent optical communications, Journal of Lightwave Technology, Vol. 25, No. 9, September 2007, pp 2675- 2692 [15] C. Hebebrand, et al.: Investigation of phase noise compensation methods for 43 Gbit/s RZ-DQPSK multispan transmission with direct detection, 9. ITG- Fachtagung Photonische Netze, 2008 [16] C. Hebebrand, W. Rosenkranz: Electronic dispersion compensation for 107Gb/s coherent detection with multilevel modulation formats, Proc. ECOC 2007, paper P063 © 2010 ACADEMY PUBLISHER Christina Hebebrand was born in 1978 in Lünen, Germany. She received the diploma degree in electrical engineering in 2003 from the University of Dortmund, Germany. Since then she is working towards the Ph.D. degree at the chair for communications, University of Kiel, Germany. Her current research interests include coherent reception, multi-level modulation formats and digital signal processing in high speed optical communications. Christina Hebebrand is student member of IEEE. Werner Rosenkranz studied Electrical Engineering at the University of Erlangen-Nurnberg, Erlangen, Germany. There he received the Ph.D. and the Habilitation at the Lehrstuhl für Nachrichtentechnik. He worked on Phase-locked Loops, digital FM-systems, and Digital Signal Processing. In 1989 he joined Philips Kommunikations Industrie and Lucent Technologies in Nuremberg, Germany, where he was responsible for a transmission group in the basic development team. In 1997 he became Professor and holds since then the Chair for Communications in the Department of Engineering of the University of Kiel, Germany. His main research activities are transmission-aspects in digital communication systems with focus on optical transmission, synchronization systems, and simulation. He is author or coauthor of more than 150 publications on selected topics as e.g. compensation and equalization of optical transmission channels, advanced modulation formats in optical communications, high-speed transmission, modeling of channel impairments etc. Prof. Rosenkranz is a member of IEEE, OSA, VDE and ITG.
JOURNAL OF NETWORKS, VOL. 5, NO. 2, FEBRUARY 2010 165 A New All-Optical Switching Node Including Virtual Memory and Synchronizer Selma Batti 1 , Mourad Zghal 2 , and Noureddine Boudriga 1 1 CN&S and 2 Cirta’Com laboratories Engineering school of communication of Tunis, Ghazala Technopark, Ariana, 2083 Tunisia Corresponding author’s Email: nab@supcom.rnu.tn Abstract— This paper presents an architecture for an all optical switching node. The architecture is suitable for optical packet and optical burst switching and provides appropriate contention resolution schemes and QoS guarantees. A concept, called virtual memory, is developed to allow controllable and reasonable periods for delaying optical traffics. Related to its implementation, several engineering issues are discussed, including the use of loopbased optical delay lines, fiber Bragg gratings, and limited number of signal amplifications. In particular, two implementations using optical flip-flop and laser neuron network based control units are analyzed. This paper also discusses the implementation and performance of an alloptical synchronizer that is able to synchronize arriving data units to be aligned on the clock signal associated with the beginning time of slots, in the node, with an acceptable error. Index Terms—optical burst switching, optical packet switching, optical synchronizer, virtual optical memory, optical delay lines I. INTRODUCTION Optical packet and burst switching (OPS/OBS) technologies are very promising solutions for the next generation Internet backbone [1, 2, 3]. Recently, a large activity has been performed for these technologies to build models, techniques, and tools to provide better quality of service and higher traffic control for optical communication. Unfortunately, the current state of the development of these technologies cannot offer explicit transfer guarantees. In fact, major lacks concerns the constraining QoS parameters and the contention resolution. The main reasons behind these limits are related to two points. The first one is the lack of optical memory and the second one is the inappropriateness of processing techniques applied to the optical signal. The major contribution of this paper is four-fold: First, a novel concept, called virtual optical memory, is presented. Its implementation is discussed through the use of loop-based optical delay lines, fiber Bragg gratings, and limited number of signal amplifications. Second, this paper proposes an all optical synchronizer that allows arriving data units to be aligned on the same © 2010 ACADEMY PUBLISHER doi:10.4304/jnw.5.2.165-179 clock signal associated with the beginning time of slots, with an acceptable error. Third, various engineering issues related to the control, loop length, and amplification of the virtual optical memory and the synchronizer are addressed and their impact on node performance is analyzed. Finally, an optical node architecture suitable for optical packet and burst switching and QoS provisioning that builds on the architecture presented by the authors in [4] by adding mechanisms that use output full range wavelength converters [5] and sharing virtual optical memories. The proposed architecture node is a hybrid node supporting both technologies, and it operates with both (short) optical packet and (long) optical bursts at the same time. The architecture operates with long bursts from some tens/hundreds of microseconds to some milliseconds. Bursts are assumed to be segmented using conventional techniques [6]. While the architecture provides an efficient contention resolution scheme [7] and helps the provision of differentiated and optimized services to IP-based applications through the use of a set of novel traffic engineering protocols providing QoS guarantees, the virtual optical memory contributes efficiently in allowing dynamic management of the traffic parameters, admission control, contention resolution, real-time congestion control, and performances monitoring. By allowing a controllable delay on each node of an all-optical network, the contention can be resolved (or at least highly reduced) by allowing all the contending flows, except one, to be delayed within shared virtual memories. In addition, an admission control and congestion resolution can be implemented using a technique that estimates the state of the nodes based on a prior description of the traffic flowing through the nodes. On the other hand, two schemes have been considered to make available QoS provision over the considered architecture [4]. The first scheme is a relative service differentiation based on burst segmentation and a segment-priority based contention resolution. The second scheme aims to provide an absolute QoS guarantee based on the dynamic management of traffic parameters instead of static priorities [8]. Fortunately, both schemes allow a better QoS provision and the optimization of resource utilization in the architecture proposed in this paper. Our architecture adopts a time slotted (or synchronous) optical packet and burst switching to make
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Aims and Scope. Call for Papers and
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