126-Robust satellite AIS receivers based on signal classification techniques

  • Doctorat
  • Temps plein
  • Moins de 2 ans
  • Master, DESS, DEA, Bac+5
  • RF Payloads & System

Mission

The AIS system enables automatic identification between ships. Recently, low earth orbit satellite constellations enable to extend the maritime traffic knowledge to off-shore regions, opening therefore new commercial opportunities.
Problems and objectives of the thesis:
The reception of AIS signals by LEO satellites is difficult for at least two main reasons: (i) the propagation channel (low signal-to-noise ratio, doppler shift) and (ii) the wide geographical coverage which includes several AIS cells, especially when the traffic is dense, thus inducing AIS message collisions at the satellite side.
Contributions have been proposed to cope with these issues, including advanced detection, synchronization [1,2], demodulation algorithms [3,4] and multiple antenna processing [5]. But improvements are limited by interferences [6] which consist not only of AIS collisions, but also of other various terrestrial VHF communications. Many publications are concerned with interference mitigations, like e.g. adaptive interference suppressions based on array signal processing. They assume though an array of antennas. For AIS signals, beamforming capabilities are limited by the shape, the size and the number of antennas handled by the satellite. So space-time techniques have been proposed as in [7] where interferences are discarded even when in the same direction as the signal of interest, provided they be narrow band with respect to the signal of interest.
The identification of the main characteristics of AIS interferences would help to improve the robustness of the AIS receiver and lower the fluctuations of the AIS message detection and demodulation rate. Classic as well as recent classification techniques (e.g. machine learning) should be investigated to serve that purpose. Using identified features of interferences or previously detected AIS bursts could help interference suppression by using an ad-hoc algorithm while keeping the complexity low enough for onboard processing. Reducing the detection complexity and dedicating the processing power to some specific signals of interest are two tracks to be considered.
Expected Contributions of the Thesis

State of the art of adaptive interference suppression techniques, and their compatibility with antenna constraints on AIS frequencies onboard satellites.
Proposition of a classification of possible various VHF interferences and jammers
Automatic interferences classification with the help of classic and more recent signal processing techniques (e.g. machine learning)
Proposition of robust detection / demodulation algorithms taking into account the characteristic knowledge of the received interference including previously detected AIS bursts.
Extension of the contributions to real-time signals

References​
[1] K. Nozaki, Y. Takanezawa, Y. Chang, K. Fukawa and D. Hirahara, ""Multiuser Detection of Collided AIS Packets with Accurate Estimates of Doppler Frequencies,"" 2021 IEEE 93rd Vehicular Technology Conference (VTC2021-Spring), 2021, pp. 1-5
[2] W. Lan et al., ""A pipelined synchronization approach for satellite-based automatic identification system,"" 2016 IEEE International Conference on Communications (ICC), 2016, pp. 1-6
[3] PRÉVOST, Raoul, et al. ""Utilisation partielle du CRC pour la correction d’erreurs des signaux AIS reçus par satellite."" Proc. Groupement de Recherche en Traitement du Signal et des Images (GRETSI), September 8-11, 2015.
[4] Malek Messai, Colavolpe Giulio, Karine Amis Cavalec, Frédéric Guilloud. Robust Detection of Binary CPMs With Unknown Modulation Index. IEEE Communications Letters, Institute of Electrical and Electronics Engineers, 2015, 19 (3), pp.339 - 342.
[5] M. Picard, M. R. Oularbi, G. Flandin and S. Houcke, ""An adaptive multi-user multi-antenna receiver for satellite-based AIS detection,"" 2012 6th Advanced Satellite Multimedia Systems Conference (ASMS) and 12th Signal Processing for Space Communications Workshop (SPSC), 2012, pp. 273-280
[6] Skauen, A.N. Ship tracking results from state-of-the-art space-based AIS receiver systems for maritime surveillance. CEAS Space J 11, 301–316 (2019).
[7] M. Zhao, H. Zhao, W. Guo and Y. Tang, ""An Interference Suppression Method Based on Space-Eigen Adaptive Processing for Satellite Communications,"" 2020 IEEE/CIC International Conference on Communications in China (ICCC), 2020, pp. 723-728.

For more Information, contact Directeur de thèse : frederic.guilloud@imt-atlantique.fr


about the topics and the co-financial partner (found by the lab !). Then, prepare a resumé, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online !

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engineering school / master 2 degree in signal processing

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