Vous êtes ici : Accueil » Kiosque » Annonce

Identification

Identifiant: 
Mot de passe : 

Mot de passe oublié ?
Détails d'identification oubliés ?

Annonce

20 février 2020

Cognitive Radio for IoT Satellite Communications with Channel Impairments


Catégorie : Post-doctorant


(Please refer to the proposal for more details)
In this project, we aim at evaluating advanced cognitive radio techniques in case of satellite channel impairments and analyze the resulting performance loss. Afterwards, we will investigate different solutions to make them resilient to such impairments.

 

Context

Machine-to-Machine (M2M) communications are one of the central use cases in fifth generation(5G) and beyond mobile network [1]. [2] predicts the deployment of around 1 million devicesper km2. In this new environment and since available radio spectrum is today a scarce resource[3], one of the main faced challenges is the design of an efficient spectrum utilization anda better coordination between legacy (licensed) and future license-free services. Within thiscontext, satellite communication systems will play a key role in this deployment regardingtheir unique characteristics compared to terrestrial cellular networks, in terms of multicast andbroadcasting, mobility, global coverage (terrestrial cellular networks can cover only 20% of theEarth) with its ability to reach green spaces and hostile environments [4]. With this in mind,the search for power and bandwidth efficiency as well as the actual trend to low complexitysatellite communication systems are of the upmost importance. The recent developments inspace-qualified Software Defined Radios (SDR) [5] as well as the maturity of advanced conceptssuch as flexible payloads [6] and nano-satellites make cognitive radio a promising and feasibleapproach for a smarter spectrum management, as this technology enables dynamic spectrumaccess and reconfigurability. Cognitive radio networks’ users exhibit different priorities (licensedradios usually coined as primary users (PU) and secondary radios (known as cognitive users(CU)). The difficulty is to limit the interference of CU to PU, while ensuring QoS for CUand managing efficiently the spectrum. Three paradigms emerge [7]: (i) interweave: the CUtransmits opportunistically into the spaces not currently used by the PU; (ii) underlay: theCU adjusts its parameters in order to transmit simultaneously while respecting an interferencepower threshold and (iii) overlay: the CU has the prior knowledge of the PU message and, byusing judiciously chosen coding and signal processing techniques, is able to use simultaneouslythe PU channel (same frequency, time and polarization), without deteriorating this latter. Thefirst two schemes were well studied in [8, 9] and the last one has been investigated in thePhD thesis [10] (which will be defended at the beginning of 2020). In this latter, authorsfirstly derived a suitable system model, which takes into account the satellite parameters.This helps the analysis of the feasibility of such overlay cognitive radio techniques in the M2Msatellite context. Secondly, the authors proposed a practical implementation considering a trellisprecoding-based Dirty Paper Coding (TP-DPC) tranceiver. Thirdly, the authors developeddifferent schemes to control the transmitted CU power in different environments. Finally, asolution was proposed to deal with the so-called modulo loss. To progressively address theproblems (cognitive radio feasibility on one hand and satellite channel impairments on theother hand), all the proposed cognitive radio schemes have been optimized by considering asimplified transmission model (Gaussian-distributed noise and interference with quadrature-amplitude modulations (QAM)).

Problem and proposed solutions

In real scenarios, the satellite channel actually introduces various impairments (nonlinearitiesdue to the satellite transponder, phase noise, interference). In this project, we aim at evaluatingthe proposed techniques in [10] in case of satellite channel impairments and analyze the resulting performance loss. Afterwards, we will investigate different solutions to make them resilient tosuch impairments.

Qualifications

This postdoctoral research position is perfect for a highly-motivated researcher who wants toapply her/his solid skills in information coding and digital communications to satellite commu-nications. Applicants should:

Knowledge in satellite impairments or dirty paper coding would be a plus

Useful information

References

[1] ITU-R, “Emerging trends in 5G/IMT2020,” inGeneva Mission Briefing Series, 2016.
[2] Huawei, “5G network architechture - a high-level perspective,” inWhite paper, 2016.
[3] United States Department of Commerce, “United States radio spectrum frequency alloca-tions chart,” inhttps://www.ntia.doc.gov/files/ntia/publications/january-2016-spectrum-wall-chart.pdf, 2019.
[4] D. Minoli,Innovations in satellite communication and satellite technology. Wiley OnlineLibrary, 2015.
[5] M. R. Maheshwarappa, M. Bowyer, and C. P. Bridges, “Software defined radio (SDR)architecture to support multi-satellite communications,” inIEEE Aerospace Conference,pp. 1–10, 2015.
[6] N. Porecki, G. Thomas, A. Warburton, N. Wheatley, and N. Metzger, “Flexible payloadtechnologies for optimising Ka-band payloads to meet future business needs,” inProc. 19thKa Broadband Commun., Navigat. Earth Observat. Conf., pp. 1–7, 2013.
[7] E. Biglieri, “An overview of cognitive radio for satellite communications,” inIEEE FirstAESS European Conference on Satellite Telecommunications (ESTEL), pp. 1–3, 2012.
[8] S. K. Sharma, S. Chatzinotas, and B. Ottersten, “Cognitive radio techniques for satellitecommunication systems,” inIEEE 78th Vehicular Technology Conference (VTC Fall),pp. 1–5, 2013.
[9] M. ́Alvarez-D ́ıaz, M. Neri, C. Mosquera, and G. Corazza, “Trellis shaping techniques forsatellite telecommunication systems,” inIEEE International Workshop on Satellite andSpace Communications, pp. 148–152, 2006.
[10] L. B. C. da Silva,Cognitive radio schemes for low data rate (IoT) satellite communications.PhD thesis, supervisors: Laurent Franck and Tarik Benaddi, IMT Atlantique Bretagne -Pays de la Loire, 2020.

 

Dans cette rubrique

(c) GdR 720 ISIS - CNRS - 2011-2020.