Optimization of constellation network routing

Job Description
UNIVITY is looking for an intern to join the team in our Toulouse office and report to the System Engineering team. As an intern within the Constellation System Engineering team, you will be responsible for developing models and optimization tools for the routing of traffic through our constellation network, from the gateways to the satellite serving the user. This internship complements ongoing work on the optimization of the user link (beamforming and frequency plan). Your work will focus on everything upstream of it: the gateways, the feeder links and the inter-satellite links. In a low-orbit constellation, this network is highly dynamic: satellites move, inter-satellite links appear and disappear, gateway visibility changes every few minutes and links can degrade or fail. You will help answer three key questions: which gateway should carry the traffic of which user, which path the packets should follow across the constellation, and how the network should fall back when a link, a satellite or a gateway becomes unavailable. Your

Key Responsibilities
And Tasks
• State of the art on the models and algorithms used for:
• Routing in dynamic, time-varying networks, in particular LEO/VLEO satellite constellations with inter-satellite links
• Gateway selection, feeder link assignment and load balancing
• Traffic engineering and QoS-aware routing (e.g. MPLS-TE, segment routing, SDN-based approaches)
• Network resilience: protection, restoration and rerouting mechanisms
• Modelling of the constellation network: time-varying topology (intra-plane and cross-plane inter-satellite links, satellite–gateway visibility), link capacities and latencies, traffic demand, and link availability (e.g. weather impact on feeder links)
• Design of optimization models and algorithms addressing at least:
• Gateway selection: assignment of user traffic to gateways, accounting for gateway and feeder capacity, latency, landing constraints and switchover frequency
• Path computation: routing of packets across inter-satellite and feeder links, maximizing the carried traffic under capacity and latency constraints
• Fall-back strategies: backup paths, rerouting upon inter-satellite link, satellite or gateway outage, and graceful degradation of the service
• Implementation of the corresponding models and algorithms, in interaction with the existing constellation and user-link optimization tools so that end-to-end capacity can be assessed
• Benchmarking of the different models and algorithms implemented in terms of carried traffic, latency, solution quality, convergence, robustness to failures, computation time and scalability to the full constellation size Requirements Skills and

experience:
• Minimum Masters 2 level (or final year of engineering school) related to one of the following topics: networks and telecommunications, operations research, computer science.
• Solid background in computer networks is required: IP routing, routing protocols and traffic engineering (e.g. OSPF/IS-IS, MPLS, SDN).
• Knowledge of optimization techniques: graph algorithms (shortest paths, multi-commodity flows), linear and integer programming, and/or heuristics and metaheuristics.
• Good programming skills (Python and/or Java). Experience with optimization solvers (e.g. Gurobi, CPLEX, OR-Tools) or network simulation tools is a plus.
• Experience in satellite systems, space networks or 5G networks is a plus but not mandatory.
• Excellent written and oral communication skills in French and English.
• Team player with excellent interpersonal skills. People come in different shapes and sizes and it is difficult to write a

job description
for someone we have not yet met. Therefore if you are not sure that you meet all the criteria, or if you think that you may have something different to offer, we still want to hear from you.