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About Me

I’m an associate professor at IMT Atlantique in the ADOPNET team. I work on the optimization of virtualized networks.

Latest publications

      Virtual Multi-Topology Routing for QoS Constraints
      by Huin, Nicolas and Martin, Sébastien and Leguay, Jérémie
      in NOMS 2024-2024 IEEE/IFIP Network Operations and Management Symposium
      Bibtex
      @inproceedings{huin_2024,
        author = {Huin, Nicolas and Martin, Sébastien and Leguay, Jérémie},
        title = {Virtual Multi-Topology Routing for QoS Constraints},
        year = {2024},
        booktitle = {NOMS 2024-2024 IEEE/IFIP Network Operations and Management
                         Symposium},
        pdf = {huin_2024.pdf}
      }
      
      Routing and Slot Allocation in 5G Hard Slicing
      by Huin, Nicolas and Leguay, Jérémie and Martin, Sébastien and Medagliani, Paolo
      in Computer Communications
      Abstract
      Current network slicing solutions suffer from poor inter-slice isolation, as the performance of one slice can be influenced by the traffic in other slices. New technologies such as Flex Ethernet can offer hard isolation via dedicated resources at the physical and MAC layers. However, to create cost-efficient hard slices in large 5G access networks, a “routing and slot allocation” must be solved quickly. While the underlying network design problem is not new, two extra constraints need to be considered: a specific order in slot activations and a bandwidth allocation policy with statistical multiplexing. We propose a compact and extended formulation to derive FlexE-CG, an algorithm based on column-generation to solve large instances. We reinforce the extended formulation to improve the lower bound by deriving valid inequalities, and we provide necessary and sufficient conditions under which the inequalities are facet-defining. We show that these inequalities improve the lower bound by more than 20% on various IP-Radio Access Networks ( RAN). We also show that FlexE-CG can provide solutions within an optimality gap of 10% in a few minutes.
      Bibtex
      @article{huin_routing_2023,
        title = {Routing and Slot Allocation in 5G Hard Slicing},
        volume = {201},
        issn = {01403664},
        url = {https://linkinghub.elsevier.com/retrieve/pii/S0140366423000166},
        doi = {10.1016/j.comcom.2023.01.008},
        pages = {72--90},
        journaltitle = {Computer Communications},
        shortjournal = {Computer Communications},
        author = {Huin, Nicolas and Leguay, Jérémie and Martin, Sébastien and Medagliani, Paolo},
        urlyear = {2023-02-22},
        year = {2023},
        langid = {english}
      }
      
      Optimal placement of virtualized DUs in O-RAN architecture
      by Ndao, Amath and Lagrange, Xavier and Huin, Nicolas and Texier, G\’ eraldine and Nuaymi, Loutfi
      in 2023 IEEE 97th Vehicular Technology Conference (VTC2023-Spring)
      Abstract
      Open Radio Access Network (O-RAN) is very promising for flexible and efficient 5G and 6G wireless networks. The O-RAN architecture consists of three main units: Radio Unit (RU), Distributed Unit (DU) and Centralized Unit (CU). In this paper we study the placement of virtualized DUs. This placement has strong consequences on cost and delay, among other, and is then an important challenge. First, we analyze the throughput between the O-RAN interfaces. Based on our analysis, we propose an efficient Integer Linear Programming (ILP) model. The objective is to minimize the O-RAN cost depending on the DU placement while respecting the delay and capacity constraints. We evaluate our model on a real topology. Our results provide interesting insights on the cost savings with regard to a legacy architecture. Moreover, the proposed model provides solutions, in a configuration where a fully centralized Cloud RAN architecture would not. We also estimate the limits of capacity of a given configuration.
      Bibtex
      @inproceedings{ndao_2023,
        title = {Optimal placement of virtualized DUs in O-RAN architecture},
        author = {Ndao, Amath and Lagrange, Xavier and Huin, Nicolas and Texier, G\' {e}raldine and Nuaymi, Loutfi},
        year = {2023},
        hal_id = {hal-04117608},
        booktitle = {2023 IEEE 97th Vehicular Technology Conference (VTC2023-Spring)
                         },
        pdf = {ndao\_2023.pdf}
      }
      
      An Approach to Network Service Placement Reconciling Optimality and Scalability
      by Taghavian, Masoud and Hadjadj-Aoul, Yassine and Texier, Geraldine and Huin, Nicolas and Bertin, Philippe
      in IEEE Transactions on Network and Service Management
      Abstract
      The inevitable transition from physical dedicated hardware devices towards lightweight containerized reusable software modules with Network Function Virtualization (NFV) introduces countless opportunities while presenting several unprecedented challenges. Satisfying NFV expectations in post-5G networks heavily depends on the efficient placement of network services. In this paper, after modeling the placement problem and proposing the exact resolutions using Integer Linear Programming and Column Generation we propose our deterministic placement solution, capable of obtaining optimal results with the scalability of a heuristic-grade approach. Our method is organized as a Branch-and-Bound structure, applying AI search strategies (especially A\textasteriskcentered) to address the problem of network service placement. We believe that it is suitable for a range of applications in online placement scenarios, whether we concentrate on the quality of the results or on the strict time constraints. We are interested in the popular objective of Service Acceptance maximization and have carried out several extensive evaluations. The obtained results confirm the effectiveness of our solution.
      Bibtex
      @article{taghavian_approach_2023,
        title = {An Approach to Network Service Placement Reconciling Optimality and
                     Scalability},
        author = {Taghavian, Masoud and Hadjadj-Aoul, Yassine and Texier, Geraldine and Huin, Nicolas and Bertin, Philippe},
        year = {2023},
        journaltitle = {IEEE Transactions on Network and Service Management},
        shorttitle = {IEEE TNSM},
        pdf = {taghavian\_approach\_2023.pdf}
      }
      
      A Fair Approach to the Online Placement of the Network Services over the Edge
      by Taghavian, Masoud and Hadjadj-Aoul, Yassine and Texier, Geraldine and Huin, Nicolas and Bertin, Philippe
      in 19th International Conference on Network and Service Management (CNSM)
      Abstract
      Unavoidable transition from rigid dedicated hardware devices towards flexible containerized network services, introduced by Network Function Virtualization (NFV), brings novel opportunities while several new challenges. Meeting the expectations of NFV in post-5G networks depends on the efficient placement of the services. The online placement of the network services, demanding strict end-to-end latency requirements over the edge networks, with restricted computing resources presents a challenging problem which is worth investigating. We propose a Branch-and-Bound search approach for finding optimal placements of the network services by applying several different cost functions to maximize the service acceptance. Extensive evaluations has been carried out, and the results confirm significant improvements when we consider a fair distribution of the resources on the edge.
      Bibtex
      @inproceedings{taghavian_fair_2023,
        title = {A Fair Approach to the Online Placement of the Network Services
                     over the Edge},
        author = {Taghavian, Masoud and Hadjadj-Aoul, Yassine and Texier, Geraldine and Huin, Nicolas and Bertin, Philippe},
        year = {2023},
        booktitle = {19th International Conference on Network and Service Management
                         (CNSM)}
      }