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11 février 2021

PhD Thesis in Space Laser Communications, Ecole Centrale Marseille/Fresnel Institute

Catégorie : Doctorant

The aim of this thesis is to propose efficient Free-space optical (FSO) transmission techniques between microsatellites to constitute a very high speed, low latency, and robust backbone network.Furthermore, effective pointing, acquisition and tracking solutions will be tailored to manage pointing errors effect. The thesis will also investigate the performance of quantum key distribution protocols over intersatellite links.


Main objectives and description of the project

The aim of this thesis is to propose efficient Free-space optical (FSO) transmission techniques between microsatellites to constitute a very high speed, low latency, and robust backbone network.

On the one hand, advanced transmission techniques will be proposed to establish high-speed and high-reliability communication links between microsatellites. On the other hand, appropriate and effective pointing, acquisition and tracking (PAT) solutions will be designed to reduce pointing errors effect. Since the current advancement in developing quantum key distribution (QKD) links whether over an optical or terrestrial FSO link is limited by the link range due to exponential attenuation of optical signal in both channels, in this project, we will also investigate the performance analysis of QKD protocols over intersatellite links as the building blocks of a space network that can possibly connect every two points on earth.

Regarding signal transmission, the proposed solutions must take into account the effect of atmosphere for which it is necessary to develop suitable statistical models, as well as that of payload vibrations, which can cause relatively large pointing errors. With regard to PAT techniques, the particularities of these links, such as the type of laser beams used, the characteristics of the payloads, and the constraints on the implementation complexity, must be taken into account.

Past experience and collaborations:

Our research laboratory (Fresnel Institute) has a rich expertise of more than 15 years on the FSO technology in different application contexts, such as terrestrial links, FSO links between UAVs, with high-speed trains, etc., and has gained an international reputation in this field.

This thesis will be carried out in close collaboration with the "LiFi Research Center" laboratory at the University of Edinburgh with several planned short stays in this laboratory throughout the thesis.

It will also benefit from an international collaborative network on space communications within the framework of a collaborative project currently coordinated by the Fresnel Institute (H2020 COST Action CA19111).

Required skills:

The candidate must have a Master (MSc or equivalent) degree by Sept. 2021. The start of the thesis is planned for Sept./Oct. 2021.

A solid background in signal processing techniques is an important asset, as well as a good knowledge of optics and optoelectronics. An experience or training in digital communications is also very welcome. The candidate must have a very good English language proficiency (oral and written expression) and be keen for short-term stays in partner laboratories.

How to apply:

Interested candidates are requested to send their CV and cover letter by email before 20 March 2021 to Dr. Ali Khalighi, Email: Ali.Khalighi@fresnel.fr


[1] S. Clarck, SpaceX smashes record with launch of 143 small satellites, SPACEFLIGHTNOW, 24 Jan. 2021, https://spaceflightnow.com/2021/01/24/spacex-launches-record-setting-rideshare-mission-with-143-small-satellites/

[2] Optical inter-satellite links are best tech for Galileo, ESA, Shaping the Future, 12/07/2019, https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Shaping_the_Future/Optical_inter-satellite_links_are_best_tech_for_Galileo

[3] E. Diamanti, A step closer to secure global communication, News and Views, 22 June 2020, https://www.nature.com/articles/d41586-020-01779-7

[4] Real-world intercontinental quantum communications enabled by the Micius satellite, University of Science and Technology of China, https://phys.org/news/2018-01-real-world-intercontinental-quantum-enabled-micius.html

[5] M.A. Khalighi, M. Uysal, “Survey on Free Space Optical Communication: A Communication Theory Perspective,” IEEE Communications Surveys & Tutorials, 2014

[6] M.T. Dabiri et al., “Blind Signal Detection Under Synchronization Errors for FSO Links with High Mobility,” IEEE Transactions on Communications, 2019.

[7] M.T. Dabiri et al., “Channel Modeling and Parameter Optimization for Hovering UAV-Based Free-Space Optical Links,” IEEE Journal on Special Areas in Communications, Special issue on Airborne Communication Networks, 2018

[8] G. Yang et al., “Performance evaluation of receive-diversity free-space optical communications over correlated Gamma-Gamma fading channels,” Applied Optics, 2013.

[9] M.A. Khalighi et al., “Double-laser differential signaling for reducing the effect of background radiation in free-space optical systems,” IEEE/OSA Journal of Optical Communications and Networking, 2011.

[10] M.A. Khalighi et al., “Fading reduction by aperture averaging and spatial diversity in optical wireless systems,” IEEE/OSA Journal of Optical Communications and Networking, 2009.

[11] F. Xu et al., “Coded PPM and multi-pulse PPM and iterative detection for Free-Space optical links,” IEEE/OSA Journal of Optical Communications and Networking, 2009.

[12] F. Xu et al., “Channel coding and time-diversity for optical wireless links,” Optics Express, 2009.

[13] H. Safi, A. Dargahi, J. Cheng, and M. Safari, "Analytical Channel Model and Link Design Optimization for Ground-to-HAP Free-Space Optical Communications," J. Lightwave Technol. 38, 5036-5047, 2020.

[14] S. Huang and M. Safari, "Free-Space Optical Communication Impaired by Angular Fluctuations," in IEEE Transactions on Wireless Communications, vol. 16, no. 11, pp. 7475-7487, Nov. 2017.

[15] N. Gisin, G. Ribordy, W. Tittel, H. Zbinden, "Quantum cryptography," Rev. Mod. Phys. 74, 145-145 (2002).

[16] M. Safari, M. Uysal, "Relay-Assisted Quantum-Key Distribution Over Long Atmospheric Channels," J. Lightwave Technol. 27, 4508-4515, 2009.


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