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Theses

Dispositif communicant par optique sans fil pour les transmissions audio à l’intérieur du cockpit d’un avion

Abstract : The work developed in this thesis is part of the European project H2020 Clean Sky 2 entitled ALC (« Aircraft Light Communication ») which aims to provide a proof of concept of the integration of optical wireless technology in the aircraft cockpit, as an alternative to radio frequency and wired solutions, having several limitations like safety and comfort. The work carried out in this thesis concerns the development of a headset communicating in infrared in a bidirectional network made of an access point located at the cockpit ceiling and four helmets worn by the crewmembers. We started by presenting the digital communication techniques that can be used in the context to motivate the choice of the study of OOK (« on-off keying»), PPM (« pulse-position modulation») modulations and DCF («distributed coordination function») with RTS/CTS (« request to send/clear to send »). Then, the transceiver main characteristics have been identified and the optical channel was modeled using the RaPSor simulation software, developed at XLIM/SYCOMOR and based on raytracing method associated with a Monte-Carlo technique. This modelling, based on a 3D model of the cockpit and the bodies of the crewmembers, allowed determining the optimal half-power angles of the sources located on the access point and on the headsets, taking into account the robustness against the random movements of the crew members during the flight. The static gains from the channel modelling were then used in a joint study of the performance of the physical and data link layers. This study highlighted the trade-off between the emitted power level and latency for a targeted quality of service. We have shown that it is possible to design an optical wireless network in an AIRBUS A350 cockpit compliant with the IEEE802.11 standard with: 4-PPM modulation, DCF with RTS/CTS channel access method, a packet error rate of 10-4 and a successful communication delay of 2.5ms. This is possible if the contention window parameter defined in the IEEE802.11 standard specifications is adapted according to the network probability collision, packets size and the data rate. Finally, we designed a modular test bench based on software defined radio. We chose the GNU Radio environment associated with USRP (« universal software radio peripheral »). Specific optical front-ends have been developed for this aim. We have experimentally shown the influence of the source parameters on the packet error rate. The work carried out in this thesis opens several perspectives in terms of simulation and experimentation.
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Steve Joumessi Demeffo. Dispositif communicant par optique sans fil pour les transmissions audio à l’intérieur du cockpit d’un avion. Optique / photonique. Université de Limoges, 2020. Français. ⟨NNT : 2020LIMO0065⟩. ⟨tel-03129846⟩

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