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.

Dynamic behavior of wavelength converters based on FWM in SOAs

Abstract: As wavelength converters based on four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) attract more attention, dynamic effects and wavelength dependent performance become key aspects to be investigated. Such issues are particularly important, as complex configurations are likely to be used to overcome challenges like tunability and polarization dependence. In this paper a numerical model is used to predict the dynamic performance of three FWM configurations and an analytical model is used to derive design rules. First, the wavelength dependent behavior of a wavelength converter is investigated and the requirement for a widely tunable converter is identified. Secondly, a configuration for extinction ratio (ER) improvement is studied and novel design rules are obtained analytically, tested experimentally and explained by the numerical model; experimental results with ER improvement at 10 Gb/s were achieved for the first time. The third configuration studied is a dual-pump arrangement enabling wide tunability. Fixed input/tunable output and tunable input/fixed output configurations are discussed in terms of optical signal-to-noise ratio and tunability. Design rules are extracted and verified for all three configurations that are likely to be deployed: simple wavelength converters, regenerating converters and tunable wavelength converters.

Dimensioning the Future Pan-European Optical Network With Energy Efficiency Considerations

Abstract: This paper studies the overall energy consumption of a pan-European optical transport network for three different time periods: today and in five and ten years from now. In each time period the pan-European network was dimensioned using traffic predictions based on realistic data generated by the optical networking roadmap developed in the framework of the European project Building the Future Optical Network in Europe-BONE. A wavelength routed wavelength division multiplexed optical network based on either transparent or opaque node architectures was examined considering exclusively either 10 Gbit/s or 40 Gbit/s per channel data rates. The results manifest that transparent optical networking technologies are expected to provide significant energy savings of the order of 35% to 55%. It was also shown that the migration towards higher data rates, i.e., from 10 Gbit/s to 40 Gbit/s, is assisting in improving the overall energy efficiency of the network.

A hybrid centralised-distributed network management architecture

Abstract: Distributed network management (NM) architectures exploiting the advantages of mobile agents (MA) promise to relieve some of the limitations intrinsic to client-server based centralised NM, such as lack of scalability, interoperability and flexibility. However, the use of MAs alone could impose an unnecessary transmission overhead if mobile code were to be used for trivial tasks. Hence, an infrastructure based on a hybridisation of centralised and distributed approaches is proposed, which maintains the lightweight nature of centralised NM for trivial management tasks, whilst adopting a distributed MA-based scheme as task complexity and suitability changes. Remote processing and compression of NM data issues are investigated in order to reduce the bandwidth usage. Security enhancements are also considered.

Using Mobile Agents for Distributed Network Performance Management

Abstract: The intrinsic limitations of traditional centralised Network Management (NM), such as information bottlenecks and lack of flexibility, have encouraged a trend towards distributed management intelligence. Although several distributed NM architectures, exploiting the advantages of Mobile Agents (MA) have been recently proposed, when considering Network Performance Management (NPM) they fail to address scalability problems. In this paper, we describe a secure and fault-tolerant management framework based on MAs, which addresses these limitations by introducing two efficient, lightweight polling modes. Both real-time and off-line NM data acquisition is considered. An in-depth performance analysis of the introduced polling modes, in a data-intensive NPM application is also undertaken. The two modes are shown to outperform SNMP-based polling both in terms of response time and bandwidth consumption.

Fast and widely tunable optical packet switching scheme based on tunable laser and dual-pump four-wave mixing

Abstract: An optical packet switching scheme based on a fast electronically controllable tunable laser dual-pump four-wave mixing for wavelength conversion and an N/spl times/N arrayed waveguide grating for passive routing is examined. This scheme can realize ultrafast packet switching and large port switch fabrication, required in next-generation core optical packet routers. The performance is examined in terms of packet-based bit-error-rate measurements for packet-by-packet switching. Design issues are also discussed.

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.