Mike J. O'Mahony

Bio: Mike J. O'Mahony is an academic researcher from University of Essex. The author has contributed to research in topics: Packet switching & Optical burst switching. The author has an hindex of 21, co-authored 83 publications receiving 2400 citations.

Crosstalk in multiwavelength optical cross-connect networks

Abstract: Optical crosstalk in multiwavelength optical cross-connect (multi-/spl lambda/ OXC) networks is studied. Two crosstalk mechanisms, interband and intraband crosstalk, caused by nonideal wavelength demultiplexing and space switching, are identified in this work. Their nature and accumulation behaviors are studied in detail. It has been established that the intraband crosstalk, where the crosstalk elements fall within the signal wavelength carrier band, is much more deleterious to the network end-end transparency performance. Three multi-/spl lambda/ OXC node architectures realising similar optical cross-connecting functions have been analyzed. Improvements in the most damaging intraband crosstalk can be realized by introducing a wavelength selective filter between the switch outputs and the wavelength multiplexer inputs. System penalty analyses associated with the crosstalk are also carried out using realistic system and device parameters, Both simulation and statistical analysis based approaches are presented.

Relative intensity noise for laser diodes with arbitrary amounts of optical feedback

Abstract: A unified study of the noise characteristics of semiconductor lasers with optical feedback and short external cavity length is presented. A new set of nonlinear rate equations that can describe a laser diode with any amount of optical feedback is proposed. The relative intensity noise (RIN) is calculated by using a numerical solution of these equations. This paper concentrates mainly on the moderate and strong feedback regimes. The spectral phenomena observed during the transition from the weak feedback to the "coherence collapse" regime and then to the strong feedback regime are studied and explained. The effect of the variation of some of the laser diode parameters on the RIN characteristics is also investigated.

A view on enabling-consumer oriented grids through optical burst switching

Abstract: As grid computing continues to gain popularity in the research community, it also attracts more attention from the enterprise and consumer levels. Applications in these domains generate large amounts of jobs, with individual jobs having only modest resource requirements. In this article, a novel architecture to realize a highly scalable and flexible platform for consumer-oriented grids is proposed. The architecture is based on an optical burst switched network, complemented with an advanced control and signaling plane. The architecture, functionality, and interfaces of all the relevant entities are presented and issues, current initiatives, and future directions for the control and management of these grid networks are discussed.

Results from the COST 239 project. Ultra-High Capacity Optical Transmission Networks

Abstract: The objective of COST 239 (Ultra-High Capacity Optical Transmission Networks) is to evaluate the feasibility of an optical overlay network interconnecting major cities within Europe. This European Optical Network employs wavelength routing to provide the required interconnection between network nodes. The study has a number of key activities and achievements relating to traffic modelling, transmission, network topologies and dimensioning, and protection strategies. In this paper the emphasis is on network rather than transmission aspects.

Optical burst switching (OBS) - a new paradigm for an optical Internet

Abstract: To support bursty traffic on the Internet (and especially WWW) efficiently, optical burst switching (OBS) is proposed as a way to streamline both protocols and hardware in building the future gener...

On Global Electricity Usage of Communication Technology: Trends to 2030

Abstract: This work presents an estimation of the global electricity usage that can be ascribed to Communication Technology (CT) between 2010 and 2030. The scope is three scenarios for use and production of consumer devices, communication networks and data centers. Three different scenarios, best, expected, and worst, are set up, which include annual numbers of sold devices, data traffic and electricity intensities/efficiencies. The most significant trend, regardless of scenario, is that the proportion of use-stage electricity by consumer devices will decrease and will be transferred to the networks and data centers. Still, it seems like wireless access networks will not be the main driver for electricity use. The analysis shows that for the worst-case scenario, CT could use as much as 51% of global electricity in 2030. This will happen if not enough improvement in electricity efficiency of wireless access networks and fixed access networks/data centers is possible. However, until 2030, globally-generated renewable electricity is likely to exceed the electricity demand of all networks and data centers. Nevertheless, the present investigation suggests, for the worst-case scenario, that CT electricity usage could contribute up to 23% of the globally released greenhouse gas emissions in 2030.

Advances in photonic packet switching: an overview

Abstract: The current fast-growing Internet traffic is demanding more and more network capacity every day. The concept of wavelength-division multiplexing has provided us an opportunity to multiply network capacity. Current optical switching technologies allow us to rapidly deliver the enormous bandwidth of WDM networks. Photonic packet switching offers high-speed, data rate/format transparency, and configurability, which are some of the important characteristics needed in future networks supporting different forms of data. In this article we present some of the critical issues involved in designing and implementing all-optical packet-switched networks.