Research
Modelling and Congestion Control of Communications Networks.
I am interested in the application of dynamics systems theory to internet and related network congestion control problems. This includes decentralised design and adaptation techniques for TCP; stability, convergence, efficiency and fairness issues; novel protocols for heterogeneous networks including wireless links.
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Resource Allocation in Wireless Networks.
Distributed algorithms for routing, channel allocation and scheduling in wireless networks. Recent work includes the development of analytic models of 802.11e suitable for capturing MAC performance wirh realistic traffic, a design framework for voice/data traffic QoS in 802.11e, communication-free decentralised algorithms for channel allocation in WLANs, and analytic modeling of 802.11 multi-hop mesh networks.
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Old Research
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Velocity-Based Theory (Off-equilibrium Linearisation).
Nonlinear systems are generally difficult to analyse and design. In contrast, we have a nearly complete theory of linear systems and a wealth of design methods. It is therefore very attractive to try to adopt a divide and conquer approach where we decompose a difficult nonlinear design task into simpler linear design tasks, and such approaches underly many popular engineering approaches. My interest is in mathematically establishing to what extent nonlinear analysis and design really can be carried out using linear ideas.
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Data-Intensive Modelling of Dynamic Systems.
The trend is for software systems to move off the desktop and into the environment, e.g. to appliances with embedded software which can sense and manipulate its environment. Examples range from mobile appliances and modern intelligent network infrastructures to modern cars, which are packed full of software. Decision-making software relies upon the availablility of suitable models describing the environment and the consequences of different decisions. We need tools for constructing appropriate mathematical/statisical models for real-time decision-support.
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Modelling and Control of Wind Turbines.
In pitch regulated wind turbines, the power output is regulated by adjusting the angle of the turbine blades to compensate for wind speed variations. However, the active regulation of wind turbines presents a challenging control problem as (i) the aerodynamic characteristics of the rotor are highly nonlinear; (ii) a primary control objective is to alleviate loads throughout the turbine in order to minimise fatigue damage - this is nonlinear requirement which places little penalty on normal operating loads but a great penalty on occasional high loads; (iii) the actuator bandwidth is low with tight rate limits. For details see online publications. Also
our benchmark wind turbine simulink model for evaluating control performance.
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Papers
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Past Awards
- MAC - Multi-Agent Control: Probabilistic reasoning, optimal co-ordination, stability analysis and controller design for intelligent hybrid systems. A four year Research Training Network within the European Commission's 5th Framework (EU HPRN-CT-1999-00107, PI on &euro 200k share of overall &euro 1.2M grant, 2000-2004).
- Matrix Pencil Stability Criteria (with Robert Shorten as PI, Enterprise Ireland Basic Research grant, £ 50000, 2001-2004
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- Off-equilibrium: A new paradigm for divide & conquer identification of nonlinear systems (PI, UK EPSRC grant GR/R15863, £ 310000, 2001-2004)
- SFI Principal Investigator (co-PI with Robert Shorten, Science Foundation Ireland grant 00/PI.1/C067, &euro 7.5M, 2001-2007)
- CEmACS: Complex Embedded Automotive Control Systems (with Robert Shorten as PI, EU STREP Project, &euro220k, 2004-2007).
- Resource allocation in WLAN's (PI, Science Foundation Ireland grant 03/IN3/I396, &euro 1.9M 2004-2008. Lead partner in &euro 5.9M Investigator cluster with University of Limerick, Dublin Institute of Technology and Intel Ireland.)
Current Awards
- Next Generation Communication Networks (co-PI with Robert Shorten, Science Foundation Ireland grant &euro 4.1M, 2007-2011).
- FutureComm (PRLTI grant with WIT, co-PI with David Malone on &euro 699K share of &euro 3.2M overall grant, 2007-2010)
- Network Mathematics (PRLTI grant &euro 1.5M share of &euro 2.2M HI structural grant joint with CTVR at Trinity College Dublin, 2007-2010)
- FAME (SFI-funded Strategic Research Cluster involving TSSG, TCD, UCD, UCC and the Hamilton Institute, co-PI with David Malone).
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