1. COATI Combinatorics, Optimization and Algorithms for TelecommunIcations Équipe-projet commune I3S (CNRS/Université Nice Sophia-Antipolis) INRIA Sophia-Antipolis Méditerranée Journées COMRED 2013 1

2. Team composition Bermond, J-C.DR CNRS (Emeritus) Caillouet, C.MCF UNS Coudert, D.CR INRIA (head) Giroire, F.CR CNRS Havet, F.DR CNRS (vice-head) Moulierac, J.MCF UNS Nisse, N.CR INRIA Pérennes, S.DR CNRS Syska, M.MCF UNS Hogie, L.IR CNRS (30%) Journées COMRED 2013 2 0 Post-Doc 2 assistants (part-time) Visitors 9 on-going PhDs 6 in 3 rd year 2 in 2 nd year 1 in 0 st year

3. Research activities Journées COMRED 2013 3 Technologies Wired: WDM, MPLS, SDH Wireless: wifi, LTE, microwave,… Overlay: P2P Design Connectivity Capacity Reliability, robustness Discrete mathematics Graph theory Combinatorial optimization Algorithmic Exact polynomial, exponential Approximations Centralized, distributed Operation Routing, rerouting Traffic grooming Fault tolerance Energy awareness Software Graph libraries Routing simulator Reproducibility Types of networks Connection oriented Backbone, backhaul, access Overlay

4. Scientific programme Solving problems arising from telecommunication using tools from graph theory and combinatorial optimization Journées COMRED 2013 4 TelecomNetwork design, routing Fault tolerance, power consumption Evolution of the traffic and/or the topology, etc. ModellingMore and more complex and realistic models Jointly with industrial partners Theoretical resultsStructural properties, combinatorial bounds, complexity Design and analysis of algorithms Solving efficiently combinatorial problems Exacts, approximations, parameterized, heuristics, etc. Implementation and experimentation Tests of algorithms (ensure reproducibility) Validation by industrial partners

5. Journées COMRED 2013 5 Industrial collaborations Wireless backhaul networks Design and management Experimentations Energy awareness WOC optimization Measurement power consumption vs load Routing in large scale networks Dynamic Routing Models Simulator Compact routing schemes

6. Ex: Backhaul networks Journées COMRED 2013 6 Part of the network infrastructure interconnecting access to backbone networks Technology: cables, fibres, micro-waves

7. Wireless backhaul networks Journées COMRED 2013 7 ~ 50% of worlwide traffic

8. Wireless backhaul networks Journées COMRED 2013 8 Dynamic behaviour of microwave links Problems Design/operation of networks with respect to link capacity dynamics Optimization of the power consumption Robust solutions with low impact on routing Mathematical models and approaches Linear and stochastic programming Relaxation, heuristics Variation of the capacity Environmental conditions Impact on signal propagation

9. Optimization at network scale Traffic variations over time = opportunities for energy savings Micro-wave link Distance, traffic have low impact Configuration ⇒ Gains in mW Components: IDU / ODU ~300 Wh per link ~50 Wh per ODU Journées COMRED 2013 9 To save energy, we must switch-off links !

10. Optimization at network scale Example: very low traffic (ensure connectivity) Journées COMRED 2013 10 Bad solution Long path N13-N14 High latency, delay, etc. Better solution But still long paths

11. Softwares DRMSim Dynamic Routing Models Simulator BGP & compact routing schemes Large scale, O(10k) nodes Dynamics Journées COMRED 2013 11 Sage Open source mathematical software written in Python, Cython, C/C++ Graph module (more than 100 algorithms), linear programming Documentation and tutorials Used for research & education (math, graph, ILP) Grph Java graphs optimization library Large scale graphs Dynamics

12. Journées COMRED 2013 12 MERCI !