Wolfgang Fischler

System performance improvements by codirectional Raman pumping of the transmission fiber

System performance improvements by codirectional Raman pumping of the transmission fiber were achieved in a single span 8 /spl times/ 10 Gbps WDM transmission system and a link length of 290 km.. The codirectional Raman pumping allowed for an increase of the span length by reducing the impact of nonlinear effects.

Cross-phase modulation in multispan WDM systems with arbitrary modulation formats

Cross-phase modulation (XPM) is a major performance-limiting effect in high bit-rate wavelength-division-multiplexed (WDM) networks with narrow channel spacing. In this paper, we present closed expressions for fast and accurate calculation of both XPM-induced amplitude and phase distortions of WDM channels. This is of particular importance for network optimization and examination of advanced modulation formats. By comparison with simulations, we demonstrate the wide application range of the novel method.

Germany-wide DWDM field trial: transparent connection of a long haul link and a multiclient metro network

We report on error-free multiclient transmission over a Germany-wide all-optical, configurable DWDM system. The performance of the transparent connection of a metropolitan area network and a bi-directional long haul system is investigated under real-world conditions. We report on the topology of SIEMENS part of the Germany-wide field trial KOMNET and results of transparent interconnections between different optical domains.

Current aspects of optical performance monitoring and failure root cause analysis in optical WDM networks

Currently existing dense wavelength division multiplexing (DWDM) networks start to migrate from numerous point-to-point links towards meshed, transparent, optical networks with dynamically routed light paths. This increases the need for appropriate network monitoring and supervision methods. Optical performance monitoring (OPM) has to be cost-effective. Thus additional spendings for OPM have to be significantly smaller than the savings in OPEX due to increased reliability and ease of operation, administration, and maintenance (OAM). We elaborate on different advanced monitoring concepts. First, we discuss general failure scenarios in meshed networks. Then we describe software based failure root cause analysis and its implementation. We conclude that by implementing appropriate software algorithms in the network hardware effort can be significantly reduced. Finally, we assess different advanced OPM methods which may show up as useful to enable OPM in future optical networks.

Monitoring the optical performance in a transparent and configurable metro area network

We report on experimental results of optical performance monitoring (OPM) in a transparent optical network transmitting channels modulated at 10 Gb/s. This experiment was performed in an entirely field installed DWDM ring network (DWDM ring capacity: 80/spl times/10 Gb/s) with configurable optical add drop multiplexers (OADMs) at different locations within the city of Berlin, Germany.

DWDM field trial: optical performance monitoring in a transparent and configurable multiclient metropolitan network

In this paper we present the topology of an optically transparent DWDM network testbed (part of the KomNet field-trial). We show results of our investigation on performance monitoring in the optical layer of this complex network. The testbed consists of a remotely configurable DWDM metropolitan area ring network (capable of transport up to 80x10 Gb/s) with two OADMs and one HUB/OXC and a long-haul bi-directional DWDM link (16x10 Gb/s, 8 spans over 750 km).

The Berlin City Ring—a Testbed for Future Metropolitan Networks

Dense wavelength division multiplexing (DWDM) is the key technology for future data transport. It combines transmission of data rates up to several Tb/s [1] with an overall transparency to data format and bit rate. The expected huge bandwidth demand in the near future requires an adaptability of DWDM transmission technology to metropolitan networks. Therefore, dynamically configurable DWDM transmission technology for bit rates up to 10 Gb/s has been investigated in a field trial in Berlin. This field trial is part of the KomNet research project. It is the goal of this field trial to optimize DWDM systems to metropolitan network requirements. Several aspects are in this paper: (i) A network simulation tool is described which helps to enlighten the profitability of statically and dynamically configured network nodes. (ii) A newly developed technology to add and drop single-wavelength channels is explained. (iii) The scalability of the approach is demonstrated with an aggregate capacity of 0.8 Tb/s. The equipment has already been installed in the field and is ready for experiments.