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Statistical modelling of tag antennas in a complex environment

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Français - Anglais

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General information

Reference : UMR9007-JEALAH-002
Workplace : MARNE LA VALLEE
Date of publication : Monday, February 10, 2020
Scientific Responsible name : Benoit Poussot
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

Context:
RFID (Radio Frequency IDentification) technology has a long established role in supply chains. With the growth of the Internet of Thing (IoT), the RFID technology becomes increasingly pervasive and omnipresent. For food traceability, fabric and clothing or logistics and supply chain management, there are numerous scenarios using UHF RFID (Ultra High Frequency RFID) for tracking and identification. These scenarios are complex for two reasons:
– The tag antenna is surrounded by other tags in a high density of radiating elements.
– The close environment of the tag antenna is partially known or known with uncertainties.
In a context of high density of tags in an uncontrolled environment, the strong electromagnetic interactions between the radiating elements of tags and the near environment impact the operation of RFID systems [1]- [4]. These phenomena preclude certain tags' power-up and degrade the communication performances, such as the read-range and the read-rate of tags. These problems are currently solved by increasing the number of reading systems to bring diversity and by modifying the tags' environment using mechanical vibration or electromagnetic stirring. The implementation of these solutions results in a heavy and costly infrastructure which is not suitable for large scale applicability of RFID systems and does not guarantee a 100 % reliability.
The objective of this PhD proposal is to improve the performances of RFID systems in a complex environment, not by acting on the reader infrastructure (protocols, antennas, post-processing, reader position and density, frequency diversity, movement) but by estimating the group behviour of RFID tags and optimising their performances statistically.

Objectives of the PhD thesis:
In a PhD work in progress in ESYCOM laboratory [5]- [6], the electromagnetic coupling between randomly distributed dipole antennas is analysed statistically. The input impedance of a surrounded dipole and its radiation pattern are evaluated and analysed by the appropriate statistical parameters. The analytical technique, IEMF (Induced ElectroMotive Force), is valid only for thin wire dipoles. The modelling of thick dipoles remain in this case numerical or experimental. The first studies show that the statistical behaviour of thin dipoles and thick dipoles are similar, regarding their mismatch. However, an interrogation remains concerning the behaviour of realistic tag antennas used in the context of UHF RFID. Moreover, the established model does not take into account the close environment of tag antennas and its variability.
This PhD work will be conducted through three axes:
 Integrate the variability of antenna's close environment into the statistical study conducted in the context of strongly coupled tags and analyse the impact of the latter on the antenna parameters (gain, mismatch, etc.)
 Quantify the impact of the variability of the antenna parameters on the system parameters called Key Performance Indicators (KPIs). For the RFID system, these parameters could be the read-rate and the read-range.
 Statistically study the robustness of antennas in a complex environment according to their topology and establish design rules for antennas used in this context.

References :
[1] C. Craeye and D. González-Ovejero, “A review on array mutual coupling analysis,” Radio Sci., vol. 46, no. 2, 2011.
[2] G. Marrocco, “RFID Grids: Part I—Electromagnetic Theory,” IEEE Trans. Antennas Propag., vol. 59, no. 3, pp. 1019–1026, 2011.
[3] S. Banerjee, R. Jesme, and R. Sainati, “Performance Analysis of Short Range UHF Propagation as Applicable to Passive RFID,” in 2007 IEEE International Conference on RFID, 2007.
[4] R. Fletcher, U. P. Marti, and R. Redemske, “Study of UHF RFID signal propagation through complex media,” in 2005 IEEE Antennas and Propagation Society International Symposium.
[5] I. Adjali, A. Guye, S. Mostarshedi, B. Poussot, F. Nadal and J.-M. Laheurte, “Statistical study of coupling in randomly distributed dipole sets,” 12th European Conference on Antennas and Propagation (EuCAP 2018), 2018.
[6] I. Adjali, A. Guye, S. Mostarshedi, B. Poussot, F. Nadal and J.-M. Laheurte, “Matching Evaluation of Highly Coupled Dipoles Quantified by a Statistical Approach,” IEEE Trans. Antennas Propag., under review.

Work Context

The ESYCOM Lab (Electronics, Communication systems and Microsystems Lab) has expertise in the engineering of communication systems, sensors and microsystems. These skills are combined in the Lab project around "Communicating devices and sensors for the city, the environment and the individual"

Supervising group:
Director: Jean-Marc Laheurte, Professor, ESYCOM/UPEM
Supervisor: Benoit Poussot, Associate Professor, ESYCOM/UPEM,
Application procedure:
The application file should include CV, statement of purpose, recommendation letters and all academic transcripts and may be addressed by email to Benoit Poussot (Benoit.Poussot@u-pem.fr).

Constraints and risks

No risk. Level of RF signals < 100 mW in planned experiments

Additional Information

Candidate's profile:
This PhD offer is intended for the candidates having a Master's degree or equivalent. The following conditions are required:
– Solid knowledge in electromagnetics
– Interest in applied mathematics including statistics
– Very great scientific rigour
– Interest in experimentation
– Autonomy in computer programming

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