Welcome to my homepage! You will find below some details on my work as a research engineer at France Télécom R&D - Orange Labs.

Research area

Papers

Other resources

Research area

My research activities are related to mathematical programming and operational research. Most of my work deals with linear programming and combinatorial optimization. I have special interest in:

• robust optimization and stochastic programming,
• location problems,
• unsplitable multi-commodity flow problems and routing issues.

Publications

Optimization with uncertain data

• O. Klopfenstein, Single-path routing of stochastic flows in networks, submitted. [pdf]
• F. Babonneau, O. Klopfenstein, A. Ouorou and J.-P. Vial, Robust capacity expansion solutions for telecommunication networks with uncertain demands, submitted. [pdf]
• O. Klopfenstein and D. Nace, Valid inequalities for a robust knapsack polyhedron - Application to the robust bandwidth packing problem, to appear in Networks (2010). [pdf]
• O. Klopfenstein, Tractable algorithms for chance-constrained combinatorial problems, RAIRO-Operations Research, 43 (2009), pp. 157-187. [pdf]
• O. Klopfenstein, Solving chance-constrained combinatorial problems to optimality, Computational Optimization and Applications, Vol. 45, Issue 3 (2010), pp.607-638. [pdf]
• O. Klopfenstein and D. Nace, A robust approach to the chance-constrained knapsack problem, Operations Research Letters 36 (2008), pp. 628-632.

Routing issues

• H. Hijazi and O. Klopfenstein, Performance-oriented routing in telecommunication networks, to appear in the proc. of Globecom 2010. [pdf]
• A. Bley, B. Fortz, E. Gourdin, K. Holmberg, O. Klopfenstein, M. Pioro, A. Tomaszewski and H. Ümit. Optimization of OSPF routing in IP Networks. In Graphs and algorithms in communication networks: studies in broadband, optical, wireless, and Ad Hoc networks, Springer-Verlag, 2009. (In press)
• A. Bashllari, D. Nace, É. Gourdin and O. Klopfenstein, Max-min fair survivable networks, Annals of Telecommunications, 63(9-10) (2008), pp. 511-522.
• O. Klopfenstein, Robust pre-provisioning of local protection resources in MPLS networks, proc. of DRCN 2007. [pdf]
• A. Bashllari, D. Nace, E. Gourdin and O. Klopfenstein, The MMF rerouting computation problem, proc. of the International Network Optimization Conference (INOC 2007).
• O. Klopfenstein, Rerouting Tunnels for MPLS Network Resource Optimization, European Journal of Operational Research, Vol. 188/1 (2008), pp 293-312.
• E. Gourdin and O. Klopfenstein, Comparison of different QoS-oriented Objectives for Multicommodity Flow Routing Optimization, proc. of the International Conference on Telecommunications (ICT 2006). [pdf]
• D. Nace, L.N. Doan, O. Klopfenstein and A. Bashllari, Max-Min Fairness in multi-commodity flows, Computers & Operations Research, Vol. 35-2 (2008), pp. 557-573.
• O. Klopfenstein and S. Mamy, Choosing Weights for IP Network Dimensioning Optimization, proc. of the International Symposium on Computers and Communications (ISCC 2006). [pdf]
• O. Klopfenstein, A Randomized Rounding Heuristic to Reroute Tunnels in MPLS Networks, proc. of the International Workshop on Design of Reliable Communication Networks (DRCN 2005). [pdf]
• D. Nace and O. Klopfenstein, On the lexicographically minimimum loaded networks, proc. of the International Network Optimization Conference (INOC 2005).

Logistics

• M. Chardy and O. Klopfenstein, Handling uncertainties in vehicle routing problems through data preprocessing, submitted. [pdf].

Location problems

• M. Bouhtou and O. Klopfenstein, Robust Optimization for Selecting NetFlow Points of Measurement in an IP Network, proc. of Globecom 2007. [pdf]
• E. Gourdin and O. Klopfenstein, Multi-period Capacitated Location with Modular Equipments, Computers & Operations Research, Volume 35, Issue 3 (2008), pp. 661-682. [pdf]

• Guy Deniélou Prize (2009), awarded by the UTC (Technology University of Compiègne)
• Best PhD thesis award (2009), from the Fondation d'entreprise EADS (category: Information and communication sciences)

Notes on stochastic and robust optimization (in french). [pdf]