Dieter Fiems

RG

Associate professor at Ghent University's Departement of Telecommunications and Information Processing

Research

Queueing analysis — I am interested in various topics in queueing theory. My PhD project focussed on single-server queues with server unreliability. I have also worked on polling and priority systems, numerical queueing analysis techniques, queues with M/G/∞ input, paired queueing systems, etc. In addition, I have studied various queueing systems, inspired by applications in telecommunications, health care scheduling and inventory management.

Wireless networks — I work/have worked on analytic models for various components of wireless networks including energy saving protocols in WiMax and LTE networks, energy harvesting sensor nodes, information propagation in ad-hoc networks, opportunistic scheduling, etc. I am mainly interested in tractable stochastic models for assessing the performance of such networks.

Branching processes — I work on applications of branching processes in queueing theor and epidemiology. In queueing theory, the dynamics of various polling systems can be described by branching processes. Branching processes can further be used to describe the initial phase of an epidemic (compartmental or on a network).

Health care scheduling — I work on fast and accurate numerical evaluation techniques for outpatient schedules. Such techniques are useful for optimising the schedules according to performance criteria such as patient waiting times, physician idle times, session over-time, etc. In addition, fast evaluation methods can be used to provide online patient waiting time estimation. As physicians usually see but a few patients in a session, steady state queueing analysis does not apply. Moreover, patients may be unpunctual or may not show up at all. This is joint work with Stijn De Vuyst.

Epidemics — I am interested in stochastic epidemic models and their fluid limits for information propagation in social networks. I am currently working on network epidemics with Koen De Turck, Balakrishna Prabhu and Konstantin Avrachenkov and on compartmental models with Koen De Turck and William Knottenbelt.

Optical buffers— Optical buffering is based on fibre delay lines (FDLs) as optical random access memory (RAM) does not exist. The optical packet is "stored" by sending it through a delay line. The length of the FDL and the entry time of the packet completely determine when the packet leaves the FDL. I.e., FDL lines hold the information for a fixed amount of time as opposed to RAM where one may retrieve the stored information at any time. Moreover, an FDL set cannot generate just any delay which leads to capacity loss. I have worked on queueing analysis of optical buffers with Wouter Rogiest, Koenraad Laevens, Evsey Morozov, Benny Van Houdt and Joris Walraevens.

Journal publications
Conference publications
Courses

Links to the outlines of the courses are below.
Course notes and slides are available through Minerva.