Based on a model of a typical operator network we have compared the power consumption of different broadband access technologies and architectures especially DSL, FTTN + VDSL and FTTH. Even though power management improves the performance there is still clear advantage of FTTH with respect to energy efficiency.

Data rates generated in the access network by new services and customer demand on triple play influence on the transmission capacity and flexibility of the transport network. A field trial to upgrade an existing DWDM link with 10 Gbit/s RZ- and NRZ-channels by 40 Gbit/s RZ-DQPSK-channels was performed on a link consisting of legacy G.652 fibre with two ROADM and EDFA amplification only. The field link had a length of 1047 km. To obtain a high spectral efficiency of the 40 Gbit/s transport the channel spacing was reduced from 100 GHz to 50 GHz. We investigated channel crosstalk for 50 GHz and 100 GHz channel spacing, mixed types of neighbour channels, PMD and chromatic dispersion tolerance which influence on maximum transparent transmission length and signal quality of the 40 Gbit/s signal in a field experiment.

In DWDM field experiments over 1047 km of standard fiber and in simulations we analyze the impact of crosstalk on a 43 Gb/s RZ-DQPSK channel both by 10.7 Gb/s OOK and 43 Gb/s RZ-DQPSK neighbors at 50 GHz channel spacing.

The most common model used for PMD simulations visualizes the fiber as a concatenation of a large number of birefringent elements. This system's DGD has the same Maxwellian PDF for each frequency. By measurement of certain links it is shown that the PDF of the DGD is not equal for all of the frequency bands. This behavior could be traced back to the fact that fiber links consist of a certain number of stable buried sections, with nearly no PMD changes over weeks and months. These sections are connected by sections exposed to strong temperature variations, acting as polarization rotators. This new model of a fiber link is known as the hinge model. To characterize these hinges, the temperature dependent behavior of several DCM and patch cords commonly used in WDM systems have been investigated. Measurements showed that DCM are the most active hinges. They produce approximately a full rotation in Stokes space when heated 1°C. This rotation is both reproducible and reversible. An novel model of the analyzed DCM has been developed in Matlab, which is able to reproduce the described measured behavior in simulations. The frequency dependency of the DGD's PDF leads from overall systems outage probability to frequency selective outage probability. That means instead of having a system outage at a certain outage probability, outage probabilities are connected to a number of outage channels.

We present two 8/spl times/170 Gbit/s DWDM/OTDM (1.28 Tbit/s) field transmission experiment both over more than 400 km in commercially operated legacy networks of France Telecom (FT) and Deutsche Telekom (DT), respectively. Conventional EDFA based amplification schemes as well as distributed Raman amplified systems are tested. For different levels of polarization mode dispersion due to different quality of the installed fibre infrastructure adaptive PMD compensation and polarization de-multiplexing is tested.

To simplify and improve the encryption of data in optical data transmission systems, the invention provides a method for encrypted data transmission via an optical transmission path (300) in front, in which an encrypted by means of a predetermined wavelength-dependent signal distortion optical data signal (500) is generated, this via the optical transmission path (300) is transmitted and the received optical data signal (500) is decrypted by compensating for the predetermined wavelength-dependent signal distortion. The invention further provides a trained for carrying out the process data transmission system.

In this paper a detailed capital expenditure cost model is presented taking various network elements and node architectures at the WDM layer into account. It was developed within the European NOBEL project [1] and aligned by major European network suppliers and operators. The current cost structure of WDM transport equipment is shown in a normalised format. Typical model applications are also discussed by presenting examples. This model can serve as a reference for future techno-economic research into optical transport networks in general.

In this paper the potential benefits and challenges for the introduction of optically transparent network elements in metro and backbone networks are discussed. The migration from current to next technology generation transport equipment is assessed.

Optical systems and technologies have been radically changing the telecommunication networks for past 15 years; today wavelength division multiplexing (WDM) technology, optical amplifiers, and simple optical switching elements like optical add-drop multiplexers (OADMs) are used in the backbone networks of all operators worldwide. Optical systems nowadays provide the basis for cost-effective transmission of large amounts of bandwidth over the Internet, and will enable its future growth and the spreading of new applications and services. This paper summarizes the main trends in optical networking and investigates potential future application areas. Optical system technology has become so pervasive in network design that it needs to be considered in the context of provisioning new applications and services. Therefore, the analysis is not limited to the aspects of physical transmission, but also takes into account recent developments in integrated network design as well as network control and management. The following sections describe the key functionalities of future optical network architectures, and the key findings of the theoretical analysis are supported by the results of a field trial of advanced transmission technology

This paper reports on the field transmission of N/spl times/170-Gb/s over high-loss fiber links using third-order distributed Raman amplification (DRA) in a commercially operated network of Deutsche Telekom. It gives an overview of the key technologies applied for the realization of an 8 /spl times/ 170 Gb/s (1.28 Tb/s) dense wavelength division multiplexing (DWDM) system demonstrator and summarizes long-haul transmission experiments with terabit-per-second capacity over European fiber infrastructure. Third-order DRA enabled repeaterless transmission of 1 /spl times/ 170 Gb/s and 8 /spl times/ 170 Gb/s over links of 185- and 140-km field fiber, respectively. Including an additional 25 km of lumped standard single-mode fiber (SSMF) at the end of the span, a total loss of 61 and 44 dB, respectively, was bridged.

We present a 8×170 Gbit/s DWDM/OTDM (1.28 Tbit/s) field transmission experiment over 421 km in commercially operated network of Deutsche Telekom. Stable transmission performance was achieved for all channels with BER ≤ 2.8*10-4 using adaptive PMD compensation.

We report transmission of 1/spl times/170 Gbit/s over 61 dB and 8/spl times/170 Gbit/s over 44 dB attenuating links in the network of a major European network operator. Third order distributed Raman amplification established long span configurations bridging, respectively, 210 km and 165 km repeaterless span.

We report on the impact of PMD in a 8/spl times/170 Gbit/s DWDM transmission experiment over 430 km field installed SSMF with and without PMD compensation. Stable performance is only achieved when using PMDC.

The opportunity to address special future client interfaces, i.e. IP router interfaces, and to reduce CapEx and OpEx in network domains with highly aggregated traffic are arguments for network operators to insist on the principal option to employ 40G in their backbone network. The fiber infrastructure of most network operators is adequate for a 40G introduction if parameters such as chromatic dispersion, fiber attenuation, nonlinear fiber effects are considered. Already the transition from 2.5Gbit/s to 10Gbit/s per channel the Polarization Modem Dispersion (PMD) for many operators proved to be a limiting factor. The heterogeneous distribution of PMD of cable and fiber segments enabled the operators to install 10 G systems by measuring and selecting the fibers. The migration towards 40G is limited mainly by the PMD of the fiber infrastructure. Again the heterogeneous distribution of PMD values means that only fraction of the possible links are feasible for 40G transmission. To extend the usable part of the infrastructure it is very important to define accurately the PMD limit which is acceptable for 40 G transmission.

This paper gives an overview of key technologies applied for realisation of a 8×170Gbit/s DWDM system demonstrator and summarizes results of transmission experiments with Terabit/s capacity over long-haul distances over European fibre infrastructure.