COATI

Combinatorics, Optimization and Algorithms

for TelecommunIcations

Équipe-projet communeI3S (CNRS/Université Nice Sophia-Antipolis)

INRIA Sophia-Antipolis Méditerranée

Journées COMRED 2013 1

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 3rd year

2 in 2nd year

1 in 0st year

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

Scientific programme

Solving problems arising from telecommunication using tools from graph theory and combinatorial optimization

Journées COMRED 2013 4

Telecom Network design, routingFault tolerance, power consumptionEvolution of the traffic and/or the topology, etc.

Modelling More and more complex and realistic modelsJointly with industrial partners

Theoretical results Structural properties, combinatorial bounds, complexity

Design and analysis of algorithms

Solving efficiently combinatorial problemsExacts, approximations, parameterized, heuristics, etc.

Implementation and experimentation

Tests of algorithms (ensure reproducibility)Validation by industrial partners

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

Ex: Backhaul networks

Journées COMRED 2013 6

Part of the network infrastructure interconnecting access to backbone networks

Technology: cables, fibres, micro-waves

Wireless backhaul networks

Journées COMRED 2013 7

~ 50% of worlwide traffic

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

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 !

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

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

Journées COMRED 2013 12

MERCI !