Fritz-joachim Westphal - Academia.edu (original) (raw)

Papers by Fritz-joachim Westphal

Electronics Letters, 1996

European Conference on Optical Communication, 1996

An all-optical passive WDM high capacity upgrade of a passive optical network (PON) is proposed a... more An all-optical passive WDM high capacity upgrade of a passive optical network (PON) is proposed and experimentally verified, using an arrayed waveguide grating (AWG) and direct detection receivers. The unmodified outside fiber plant and the AWG can be supervised from the central office (CO).

Our proposal adds an arrayed waveguide grating (AWG) operated at 1.5 μm to the star coupler of a ... more Our proposal adds an arrayed waveguide grating (AWG) operated at 1.5 μm to the star coupler of a passive optical network (PON) in the remote node (RN) and separates the original PON and the overlay via 1.3/1.5 μm splitters, which guarantees the maintenance function

... Due to the wavelength selfrouting property of the AWGs, each ONU can be supplied with a bitra... more ... Due to the wavelength selfrouting property of the AWGs, each ONU can be supplied with a bitrate and modulation transparent wavelength path, using direct detection receivers for up ... An additionalbenefit is, that the upgrade allows to measure all fibers of the system from the CO. ...

IEE Colloquium on WDM Technology and Applications, 1997

A concept for an all-optical wavelength division multiplexing (WDM) overlay on a passive optical ... more A concept for an all-optical wavelength division multiplexing (WDM) overlay on a passive optical network (PON) and its experimental verification is presented. The WDM overlay at 1.5 /spl mu/m is realised leaving the outside fibre plant and the operation of the existing PON at 1.3 /spl mu/m unaltered. Arrayed waveguide gratings (AWG) are used to establish a point to point connectivity via individual wavelength paths between central office (CO) and each optical network unit (ONU). To keep the remote node (RN) totally passive the AWG at the RN can be monitored from the central office.

Electronics Letters, 1988

An optical heterodyne image rejection receiver front end is reported. An image rejection better t... more An optical heterodyne image rejection receiver front end is reported. An image rejection better than 25 dB at an IF frequency of 1.5 GHz was observed. The receiver is realised in fibre-optic techniques.

Proceedings of IEE/LEOS Summer Topical Meetings: Integrated Optoelectronics, Aug 24, 2005

... Michael Hickey, F.-Joachim Westphal*, Jason Fan, Gunnar Jacobsen+, and Leonid Kamvsky ... 199... more ... Michael Hickey, F.-Joachim Westphal*, Jason Fan, Gunnar Jacobsen+, and Leonid Kamvsky ... 1994. G. K. Chang, M. Z. Iqbal, K. Bala, G. Ellinas, J. Young, H. Shirokmann, C. E. Zah, L. Curtis, B. Pathak, D. Mahoney, J. Gamelin, E. Goldstein, L. Eskildsen, and C. A. Bracken ...

In thin client computing, applications are executed on centralized servers. User input (e.g. keys... more In thin client computing, applications are executed on centralized servers. User input (e.g. keystrokes) is sent to a remote server which processes the event and sends the audiovisual output back to the client. This enables execution of complex applications on thin devices. Adopting virtualization technologies on the thin client server brings several advantages, e.g. dedicated environments for each user and interesting facilities such as migration tools. In this paper, a mobile thin client service offered to a large number of mobile users is designed. Pervasive mobile thin client computing requires an intelligent service management to guarantee a high user experience. Due to the dynamic environment, the service management framework has to monitor the environment and intervene when necessary (e.g. adapt thin client protocol settings, move a session from one server to another). A detailed performance analysis of the implemented prototype is presented. It is shown that the prototype can handle up to 700 requests/s to start the mobile thin client service. The prototype can make a decision for up to 700 monitor reports per second.

Electronics Letters, May 13, 1993

optical pulses have been generated simultaneously with a 1.9nm spacing over a 1.224-1.394pm spect... more optical pulses have been generated simultaneously with a 1.9nm spacing over a 1.224-1.394pm spectral range. The method can be easily extended to LD-based 1.5pm Gbit/s systems and offers a powerful tool for a wide variety of applications in future WDM and all-optical networks.

The rise of cloud services poses considerable challenges on the control of both cloud and carrier... more The rise of cloud services poses considerable challenges on the control of both cloud and carrier network infrastructures. While traditional telecom network services rely on rather static processes (often involving manual steps), the wide adoption of mobile devices including tablets, smartphones and wearables introduce previously unseen dynamics in the creation, scaling and withdrawal of new services. These phenomena require optimal flexibility in the characterization of services, as well as on the control and orchestration of both carrier and cloud infrastructure. This paper proposes a unified programmability framework addressing: the unification of network and cloud resources, the integrated control and management of cloud and network, the description for programming networked/cloud services, and the provisioning processes of these services. In addition proofs-of-concept are provided based on existing opensource control software components.

IEEE Photonics Technology Letters, 1994

In a circuit arrangement for optical frequency conversion. having a switchable input filter arran... more In a circuit arrangement for optical frequency conversion. having a switchable input filter arrangement with a wave length channel filter of a wavelength multiplexer/ demultiplexer which is formed using a number of such channel filters, which filter can be connected via a 1:n fiber

European Conference on Networks and Optical Communications, 1996

Residential access networks of internet service providers have evolved from copper-based public s... more Residential access networks of internet service providers have evolved from copper-based public switched telephone networks to digital broadband access networks now based on a mixture of copper and fibre infrastructure components. It is generally well accepted that an FTTH-network (Fibre-to-the-Home), where the fibre runs all the way to the customer

2021 European Conference on Optical Communication (ECOC)

2009 35th European Conference on Optical Communication, 2009

The energy consumption of a telecommunication network increases, but at a reduced slope compared ... more The energy consumption of a telecommunication network increases, but at a reduced slope compared to the assumed traffic volume increase. The major energy consumption portion shifts from access to backbone networks with rising traffic volume.

... Quantifying Interactive User Experience tin Thin Clients. WIME Computer, Volume 39 ■■ 3, page... more ... Quantifying Interactive User Experience tin Thin Clients. WIME Computer, Volume 39 ■■ 3, pages 46-52, March 200$ ¡2) Niraj T'olia, David 0. Andersen. M. Satyaaaraytman. ... March 2007" {IS) F. Travasano, P. Daspii.L. Gomnians, С Jog, С deLaat,.!, Manibretti, t Monga, В. ...

This paper gives an overview on actual trends and deployments of carrier-grade Ethernet in metro,... more This paper gives an overview on actual trends and deployments of carrier-grade Ethernet in metro, access, and core networks. This includes the related motivation, concepts, and technologies as well as open issues regarding research, development, and standardization. Ethernet as a packet-based, connection-oriented technology is deployed for metro networks worldwide today. This is driven by the massive increase of (IP-based) data traffic and the related applications. The Ethernet deployments aim at most cost-efficient data service provisioning and the migration of all legacy Layer-2 services towards a unified platform. The goal is a massive reduction of both, CapEx and OpEx. Network operators and service providers impose increased requirements regarding scalability, quality of service including reliability and availability, and Operations, Administration, and Maintenance (OAM) features on their metro Ethernet solutions. These requirements are usually referred to as carrier-grade or tr...