A. Ehrhardt

Evolution of Terrestrial Optical System and Core Network Architecture

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

512-Gb/s DP-16-QAM field trial over 734 km installed SSMF with co-propagating 10 Gb/s NRZ neighbors incorporating soft-FEC decoding

We report on a 512-Gb/s dual-carrier DP-16-QAM long haul field trial over 734 km of dispersion compensated SSMF with 10-Gb/s neighbors. Soft FEC decoding was utilized in the receiver DSP confirming successful transmission.

Field trial investigation of 16-states MLSE equalizer for simultaneous compensation of CD, PMD and SPM

We investigate 16-states MLSE equalization over buried fibers having CD up to 4480 ps/nm, PMD up to 92 ps and launch powers up to 12 dBm. Results show a superior performance for joint compensation of all distortion effects.

Monitoring of the transparent fibre infrastructure for FTTx networks: An operator's view

In the access network area the optical fibre step by step substitutes the existing copper cable infrastructure in order to enable new services requiring a steadily increasing bandwidth. The optical fibre is capable to transmit significantly higher data rates over longer distances than the copper links. In the next years new architectures like Fibre-to-the-Building and Fibre-to-the-Home will be implemented in the access networks. These fibre links require a monitoring of the infrastructure by the network operator in order the guarantee a high quality of service. The monitoring is necessary during the fibre installation with final test, regular operation of the network and for fault location. The possibilities and particularities of fibre monitoring in transparent optical access networks in comparison to the core network are described. Considering the operational conditions the preferred and suitable solutions from a view point of a network operator are shown and described in detail.

Experimental Investigation of Real Time 10 Gbit/s MLSE Equalizer Using 4-States and 16-States Viterbi Detector

Electronic equalizers are more and more applied in optical transmission systems to compensate for static as well as time varying fiber distortions. In this paper we investigate the performance of 4-states and 16-states MLSE equalizers in 10 Gbit/s field trials over buried single mode fibers. Our results show that the MLSE equalizer enables the joint compensation of chromatic dispersion up to 4480 ps/nm and polarization mode dispersion up to 92 ps. This will increase the uncompensated transmission length and enables a more robust and flexible optical link design.

8×107 Gbit/s serial WDM field trial over 500 km SSMF

8×107Gbit/s DWDM transmission is achieved over a 500km field installed fibre link in the Deutsche Telekom network, indicating high link utilization of 1bit/s/Hz spectral efficiency, needed for Terabit/s network capacity, required in a mid-term timeframe.

10 Gbit/s 750 km regenerator-free WDM field trial-upgrading an operated 2.5 Gbit/s based system without changing the installed infrastructure

A fully managed field-installed wavelength-division multiplexed (WDM) link was upgraded with a bidirectional STM-64/OC-192 system and operated with bit error rate <10/sup -13/ without changes of the dispersion-compensated SMF line to demonstrate the upgrade feasibility of transparent links. Dispersion tolerance and PMD influence were investigated.

ONT reflection for additional maintenance by OTDR-measurements in FTTH networks

ONT-reflection is used, additionally to GPON-EMS, to identify termination points in FTTH-PON-networks. OTN-reflectivity vs. wavelength is investigated. In-service OTDR-measurements from Central Office allow testing PON-branches and to distinguish optical length differences down to 2m.

Application of MLSE technology in optical communication systems and performance evaluation in 10Gbit/s field trials

In this paper we analyze the effort of realizing advanced MLSE digital equalizer technology in optical 10Gbit/s systems and evaluate its performance for ISI compensation in field applications by comparing 4-state vs. 16-state Viterbi decoders.

8/spl times/2.5 Gbit/s 2340 km transmission experiments over a replica of the Berlin-Darmstadt field transmission line

4/spl times/2.5 Gbit/s, 735/1470 km and 8/spl times/2.5 Gbit/s, 780/156/2340 km WDM transmission experiments over a dispersion compensated 735 km replica of the Berlin-Darmstadt field transmission line were carried out with directly and externally modulated WDM signals.