Title Promoter Affiliations Abstract
"Robust modelling and optimisation in stochastic processes using impreciseprobabilities, with applications to queueing" "Gert De Cooman" "Department of Electronics and information systems, Department of Industrial Systems Engineering and Product Design, Department of Telecommunications and information processing, Department of Electromechanical, Systems and Metal Engineering" "A process is called stochastic when its time-evolution is to someextent uncertain. To model and reason with such uncertainty, weuse methods from probability theory. This allows us to analyse thebehaviour of these processes, and to design or influence them inorder to make their behaviour optimal or desirable.One crucial problem is that most often we are not only uncertainabout the processes themselves, but also about the validity of theprobabilistic models we use for studying them. The theory ofimprecise probability is a recent development of probability theorythat is designed to dealing with this so-called model uncertainty ina robust way.The project aims first of all at further developing this generaltheory, all the while concentrating on techniques that are usefulfor, and tailored towards, working with stochastic processes. Atthe same time, we will apply and evaluate the developed methodsand techniques in the practically important area of queueingapplications for communication systems.The project brings together two research groups at Ghent University:SYSTeMS, whose expertise lies in robust uncertainty modellingusing imprecise probabilities, and SMACS, who are focusedon queueing theory and applications in communication.1"
"Analysis of Heterogeneous Queueing Networks" "Joris Walraevens" "Department of Telecommunications and information processing" "In this project, we study queueing networks with agiven number of classes of customers. Priority can be given to a particular class of customers when serving customers in the queues. These queueingnetworks are adequate models for nowadays telecommunication networks. We will construct approximative formulas for interesting performance measures such as the end-to-end delay of customers."
"Queueing systems with energy efficient service" "Sabine Wittevrongel" "Department of Telecommunications and information processing" "The project aims at studying mechanisms for the energy efficient service of customers in a queueing system. Particularly, the goal is the development of appropriate stochastic models, adequate mathematical techniques and efficient numerical procedures for the performance analysis of queueing sytems with exhaustive service and two types of mechanisms for resuming the service of customers: a sleep mode mechanism or a service threshold."
"Performance analysis of queueing models with AQM for scalable video" "Herwig Bruneel" "Department of Telecommunications and information processing" "The aim of this project is to investigate the performance of active queue management techniques in the nodes of a packet swithced network. In particular, various queueing models will be constructed and analysed to assess the performance of transmission of layered video over these networks."
"Development of a methodology to increase the applicability of queueing models whereby numerical calculation of boundary probabilities is required" "Herwig Bruneel" "Department of Telecommunications and information processing" "Queueing theory provides fundamental tools to study the performance of computerand telecommunication networks. Basically, a model is developed, whereuponperformance measures are deduced by which the scenario at hand can beevaluated. In a queueing model, broadly speaking, customers (packets, processes)arrive and are stored in a buffer in awaitance of their service (transmission, beingexecuted). A popular and effective technique to obtain performance measures,such as the average number of stored packets, makes use of so-called probabilitygenerating functions. However, in a broad range of scenarios, the resulting formulasfor the performance measures contain various boundary probabilities that haveto be calculated numerically, which is a drawback for applicability. The purposeof this project is to obtain accurate closed-form (i.e., no numerical calculationsrequired) approximations for the performance measures in such cases."
"Robust modelling and optimisation of stochastic processes with imprecise probabilities, applied to queueing systems" "Stijn De Vuyst" "Department of Industrial Systems Engineering and Product Design" "In this project the paradigm of impreciseprobabilities (expertise 1st promotor) is applied to stochastic processes that are usually described by U+2018commonU+2019, i.e. precise, probability theory. Thetargeted application is on processes that occur in queueing systems (expertise of 2nd and 3rd promotor). The new treatment allows us to quantify the belief we can put in results from classic queueing analysis in the presence of model uncertainty."
"A new paradigm for the service process in queueing systems, with applications in computer and communication networks." "Benny Van Houdt" "Internet Data Lab (IDLab)" "Our objective is to derive closed-form results and/or fast numerical procedures to assess the main performance characteristics of the proposed queueing models, such as throughput, customer delay, system content, loss characteristics, etc., and to apply these results in a number of relevant areas such as Cognitive Radio, Medium Access Control and server farms."
"Load balancing and scheduling in large-scale computer systems." "Benny Van Houdt" "Internet Data Lab (IDLab)" "Since the introduction of the very first communication networks, queueing models have played a key role in improving network performance. This has resulted in a large body of queueing theory literature that has found widespread use in many other areas of science and technology. As the area of computer systems and networks is ever evolving, so is the need for new, tailored queueing models. Large-scale systems (e.g., grid computing or cloud computing) have become quite prevalent today and are often composed of many heterogeneous resources. The analysis of such large-scale heterogeneous systems using traditional queueing theory is prohibitively expensive as the required time and memory complexity tends to scale poorly in the system size. The aim of this project is to introduce and analyze new queueing models that provide insight into the performance of existing and novel load balancing and scheduling algorithms for large-scale systems. The problems under consideration include affinity scheduling problems motivated by MapReduce clusters, load balancers that make use of redundancy to mitigate latency caused by server unpredictability, and stateful load balancers. The main envisioned methodology exists in developing fluid approximations that are validated using simulation experiments and that can be shown to become exact as the system size tends to infinity. The project combines techniques from stochastic modelling, probability, dynamical systems, numerical analysis and simulation."
"Design, Analysis and Optimization of Intersections of the Future" "Joris Walraevens" "Department of Telecommunications and information processing" "Intersection management algorithms need to be designed such that the efficiency and performance of intersections is maximized within the applicable safety conditions. Intelligent Transportation Systems (ITS) promise a revolution in how intersections will be designed and managed in the (near) future. First, wireless communication between vehicles and infrastructure (V2I) or between vehicles(V2V) will lead to a radically new and highly improved operation of intersections, where e.g. the infrastructure can dynamically assign some degree of priority to certain vehicle types. Secondly, by adding autonomous cars to the picture, the lack of a human factor makes that safety margins can be reduced such that efficiency can be further augmented considerably. In this project, we plan to design, model, analyze and optimize scheduling policies for managing such intersections of the future. We model individual intersections as multi-queue queueing systems and calculate performance measures using queueing theory. We also investigate how novel intersection management can be integrated in theory for complete road networks. The ultimate goal is to maximize efficiency of intersections of the future, locally as well as globally."
"Design, Analysis and Optimization of Intersections of the Future" "Chris Tampère" "Centre for Industrial Management / Traffic & Infrastructure" "Intersection management algorithms need to be designed such that the efficiency and performance of intersections is maximized within the applicable safety conditions. Intelligent Transportation Systems (ITS) promise a revolution in how intersections will be designed and managed in the (near) future. First, wireless communication between vehicles and infrastructure (V2I) or between vehicles (V2V) will lead to a radically new and highly improved operation of intersections, where e.g. the infrastructure can dynamically assign some degree of priority to certain vehicle types. Secondly, by adding autonomous cars to the picture, the lack of a human factor makes that safety margins can be reduced such that efficiency can be further augmented considerably. In this project, we plan to design, model, analyze and optimize scheduling policies for managing such intersections of the future. We model individual intersections as multi-queue queueing systems and calculate performance measures using queueing theory. We also investigate how novel intersection management can be integrated in theory for complete road networks. The ultimate goal is to maximize efficiency of intersections of the future, locally as well as globally."