Postdoctoral Researcher Position (M/F): Reducing the Computational Effort in Large-Dimension MILP applied to the Routing under Latency Constraints in Large-Scale Time-Sensitive Networks

Job Description

Missions

Project description:
The idea in RÉCITAL's research project is to describe the routing-and-configuration
problem as a Mixed Integer Linear Program (MILP) to leverage the performance of MILP
solvers. We expect that this approach can provide better results than the ones based on
gradient descent [Geyer22]. However, the obtained MILP models can be of very high
dimension in large networks.
In this Postdoctoral Research Position, we aim at identifying, testing and selecting
approaches for reducing the computational effort of the MILP models. You will work with
the PhD and permanent members that create the MILP models to identify with them the
opportunities of proposing and comparing different reformulations, valid inequalities
and decomposition techniques. For the largest problems, we aim to identify promising
heuristics providing a good coverage/accuracy/computational effort trade-off, etc.

Activity

In this Postdoctoral Research Position, we aim at identifying, testing and selecting
approaches for reducing the computational effort of the MILP models. You will work with
the PhD and permanent members that create the MILP models to identify with them the
opportunities of proposing and comparing different reformulations, valid inequalities
and decomposition techniques. For the largest problems, we aim to identify promising
heuristics providing a good coverage/accuracy/computational effort trade-off, etc.

Your Profil

Skills

PhD in operational research with contributions in integer linear programming
(modeling, decomposition, math-heuristics).
Previous work on network optimization is a plus.
Knowledge in computer networks and/or time-sensitive systems is a plus.

Your Work Environment

Background:
Time-sensitive networks are used for safety-critical cyber-physical systems (CPSs) in
vehicles, planes, satellites or power plants. Their significance has been increasing over
the years and they are now used in many more applications, ranging from autonomous
cars, automated manufactures (industry 4.0) to 5G backbone networks. While traditional
public networks aim at improving the mean service performances (mean round trip time,
mean throughput), time-sensitive networks provide guarantees for the worst case (e.g.
guarantee of a maximal latency, guarantee of no loss, …). Time-sensitive networks use
specific layer-2 technologies such as IEEE TSN [TSN] for providing deterministic latency.
Most of the time, certification authorities require formal proofs of the network timing
behavior [LeBoudec01]. Network calculus is a commonly used theory for providing such
formal proofs. Over the recent years, open-source tools based on network calculus have
been published and provide timing upper bounds for a given network configuration (ex:
for a given allocation of routes and priorities to flows).
However, time-sensitive networks control increasingly large and dynamic systems
(smart-grid systems, unmanned air traffic management, public transportation systems).
To choose a routing and configuration (ex: what paths and priorities to allocate to flows,
depending on their deadlines and traffic profile ?) for these new types of networks,
enumerating all possible configurations, analyzing them all using network-calculus tools
to retain only those that meet the flows' requirements becomes impractical. The RÉCITAL
research project proposes to start from the flow latency constraints to generate a routing
of flows and a network configuration that respect these constraints and minimize the
network usage and/or maximize the monetary value of the service.

Compensation and benefits

Compensation

between 3000 € and 3300€ gross

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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