Gheorghe Zaharia | INSA Rennes (original) (raw)

Papers by Gheorghe Zaharia

This paper presents a double extension of the mathematical Weyl group with the purpose of increas... more This paper presents a double extension of the mathematical Weyl group with the purpose of increasing the spectral efficiency of the Differential Space-Time Modulation (DSTM) scheme using this group of matrices. The error performance of the system is improved through an optimal selection of the matrices selected for a given spectral efficiency and an optimal mapping between the binary data vectors and the information matrices. Finally, the performance of the obtained system is evaluated using a more realistic time-varying channel model.

2017 Sensors Networks Smart and Emerging Technologies (SENSET), Sep 1, 2017

This paper presents a microwave system for measuring the cardiopulmonary activity performed in tw... more This paper presents a microwave system for measuring the cardiopulmonary activity performed in two ways: by using single antenna and by using two antennas. This system generates a continuous wave signal at 20 GHz toward the target and then measure the reflected signal. The target is the person's chest set placed at a distance of 1 m. The VNA measures the phase variation between the emitted and received signals. This phase variation contains information about the movement of the chest. An electrocardiograph is used simultaneously with the system as reference in order to determine the accuracy of the VNA system. The measurements are performed for a person under two conditions: breathing normally and holding the breath. Wavelet transform is used for the processing the obtained signals and the heartbeat rate is extracted accurately.

HAL (Le Centre pour la Communication Scientifique Directe), May 14, 2019

-Cet article présente les premiers résultats de l'étude de propagation dans la bande de 60 GHz, p... more -Cet article présente les premiers résultats de l'étude de propagation dans la bande de 60 GHz, prévue pour les nouveaux réseaux locaux sans fil. L'étude repose sur deux campagnes de mesures menées dans un environnement indoor. Les résultats permettent de modéliser les pertes de puissance en fonction de la distance pour différentes configurations. Par ailleurs, l'étude de la réponse impulsionnelle du canal permet de mettre en évidence la propagation par trajets multiples.

International Journal on Communications Antenna and Propagation, Jun 30, 2016

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

HAL (Le Centre pour la Communication Scientifique Directe), Aug 7, 2008

This paper presents a brief overview of several studies concerning the indoor wireless communicat... more This paper presents a brief overview of several studies concerning the indoor wireless communications at 60 GHz performed by the IETR. The characterization and the modeling of the radio propagation channel are based on several measurement campaigns realized with the channel sounder developed at IETR. Some typical residential environments were also simulated by ray tracing and Gaussian Beam Tracking. The obtained results show a good agreement with the similar experimental results. Currently, the IETR is developing a high data rate wireless communication system operating at 60 GHz. The single-carrier architecture of this system is also presented.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 23, 2015

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

HAL (Le Centre pour la Communication Scientifique Directe), Feb 4, 2009

International audienc

This paper presents characterization measurements of the dynamic propagation channel at 60 GHz in... more This paper presents characterization measurements of the dynamic propagation channel at 60 GHz in an indoor office-type environment. These measurements quantify the influence of the access point (AP) location in the presence of natural people movements. They were performed using a vector network analyzer (VNA) operating on 2 GHz bandwidth. 9900 measures of the channel frequency response were recorded over eleven hours for each receiver position. Five receiver positions were considered in line-of-sight (LOS). The obtained results allow to compute the channel path loss (PL). For each receiver location, the experimental probability distribution function (PDF) and the cumulative distribution function (CDF) of PL values were also computed and analyzed. Analysis shows that the location of the access point can have a strong impact on the quality of the radio link.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 1, 2003

ABSTRACT

2022 16th European Conference on Antennas and Propagation (EuCAP)

2019 International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob)

In this work, we present a propagation measurements campaign conducted at 60 GHz in a typical ind... more In this work, we present a propagation measurements campaign conducted at 60 GHz in a typical indoor office environment. These measurements can be useful in order to exploit multipaths, aiming to maintain the quality of the communication in the case of blocking the direct path due to an obstruction created by people, furniture or other obstacles. The measurements were realized on 2 GHz bandwidth using a vector network analyzer (VNA). At the receiving side being always visible by the transmitter, a rotation by 6 • over 360 • is performed. The obtained results allow to compute different channel parameters such as: path loss, RMS delay spread and coherence bandwidth. In our study, we consider for each receiver position two situations: the direct orientation and the best indirect orientation of the receiving antenna. These results show that the path loss of the best indirect orientation increases up to 18 dB compared to the direct orientation. Indeed, some positions may be more affected than others in the case of blocking the direct orientation. The obtained results will be useful both to design the new broadband communication systems and to deploy wireless local and personal area networks (WLAN/WPAN) operating in the millimeter-wave (mmWave) bands. Index Terms-60 GHz, indoor radio channel, measurements, VNA, path loss, RMS delay spread, coherence bandwidth, angle of arrival

2021 IEEE Conference on Antenna Measurements & Applications (CAMA), 2021

This paper presents the characterization of the propagation channel at 60 GHz in a meeting room. ... more This paper presents the characterization of the propagation channel at 60 GHz in a meeting room. This characterization was done using measurements and simulations. From measurements we provide the angular received power and the path loss using a vector network analyzer (VNA) operating on 2 GHz bandwidth. In simulations, we use ray tracing technique trying to respect the same measurements conditions, in order to obtain comparable results. Finally, we compare the measurement and simulation results in direct orientation (DO) and in best indirect orientation (BIO). This will be useful for designing beamforming techniques for future millimeter communication systems.

2019 International Symposium on Signals, Circuits and Systems (ISSCS), 2019

This paper presents the results obtained from 60 GHz propagation measurement campaigns in indoor ... more This paper presents the results obtained from 60 GHz propagation measurement campaigns in indoor environments. These measurements are performed in the frequency domain and are based on the use of a vector network analyzer (VNA). The analysis of the results makes it possible to characterize the propagation channel. In first measurement campaign, we show the influence of different types of antennas on the path loss characteristics in a hallway, while in the second campaign results highlight the effect of the type of antenna of the access point (AP) and its position on the angular impulse response of the channel inside a meeting room. All of these results are intended to lead to rules for the deployment of wireless high-speed local and personal area networks (WLANs/WPANs).

This paper presents different signal processing techniques used in separating cardiopulmonary sig... more This paper presents different signal processing techniques used in separating cardiopulmonary signals measured using a microwave Doppler radar. For different sides from the person under test, the microwave system is tested for several operational frequencies simultaneously with a PC-based electrocardiograph. Wavelet transforms are used in order to separate heartbeat signal from the cardiopulmonary signals. High accuracy is obtained in terms of heartbeat rate for the whole measurements.

2020 14th European Conference on Antennas and Propagation (EuCAP), 2020

In this work, we study the dynamic 60 GHz radio propagation channel conducted by measurements in ... more In this work, we study the dynamic 60 GHz radio propagation channel conducted by measurements in an open-space office. These measurements quantify the effect of natural people movements on the path loss before and during working hours. Thus, it’s possible to compare the effect produced by these movements with the static case when the office is empty of people. Measurements were performed using a vector network analyzer (VNA) operating on 2 GHz bandwidth. 9900 measures of power loss were recorded over eleven hours of measurements for each receiver position. Five receiver positions were considered to study three cases of receiver positions type: the line-of-sight (LOS), the obstructed-line-of-sight (OLOS) and the non-line-of-sight (NLOS). The obtained results allow to compute successively the channel path loss (PL), its probability density function (PDF) and its cumulative distribution function (CDF). Finally we compare the evolution of the dynamic channel in the presence of people at...

2016 IEEE Middle East Conference on Antennas and Propagation (MECAP), 2016

This paper presents a wireless measurement system for cardiopulmonary activity detection behind a... more This paper presents a wireless measurement system for cardiopulmonary activity detection behind a wall. This system generates a continuous wave signal and is used at 2 different frequencies: 2.4 GHz and 10 GHz. The transmitted signal is directed toward the patient's chest situated at 1 m and then reflected. The radar system is based on a vector network analyzer, which measures the phase of S 21. The phase variation of S 21 contains information about heart and respiration activity. Measurements are carried out every 30 seconds, for a person sitting at a distance of 1 meter, directly in front of the system or behind a wall. Discrete wavelet transform is used as a processing technique to separate heartbeat signal from respiratory signal. The measurements were performed simultaneously with a PCbased electrocardiogram (ECG) which is used as a reference to validate the information extracted from the measured signals.

Advanced Biosignal Processing and Diagnostic Methods, 2016

As traditional electrodes are perturbing for patients in critical cases such as for burn victims ... more As traditional electrodes are perturbing for patients in critical cases such as for burn victims or newborn infants, and even to detect life sign under rubble, a contactless monitoring system for the life signs is a necessity. The aim of this chapter is to present a complete process used in detecting cardiopulmonary activities. This includes a microwave Doppler radar system that detects the body wall motion and signal processing techniques in order to extract the heartbeat rate. Measurements are performed at different positions simultaneously with a PC-based electrocardiogram (ECG). For a distance of 1 m between the subject and the antennas, measurements are performed for breathing subject at four positions: front, back, left, and right. Discrete wavelet transform is used to extract the heartbeat signal from the cardiopulmonary signal. The proposed system and signal processing techniques show high accuracy in detecting the cardiopulmonary signals and extracting the heartbeat rate.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 1, 2003

At millimeter-waves, the home furniture and objects dimensions can be equal or superior to the wa... more At millimeter-waves, the home furniture and objects dimensions can be equal or superior to the wavelength. A comparison between propagation measurements conducted within a residential house for two configurations, furnished and empty, underscores the influence of the furniture on the millimeter-waves propagation.

arXiv (Cornell University), Dec 16, 2021

In the current development of new technologies, the world of communications is experiencing signi... more In the current development of new technologies, the world of communications is experiencing significant growth thanks to the integration of wireless communications in millimeter band. In this context, the purpose of this paper is to assess the contribution that the use of a metallic reflector panel can introduce to indoor radio coverage at 60 GHz in an NLOS (corridor) configuration. The results obtained by measurement show that the use of such a panel can lead to a significant path loss reduction up to 12 dB, which improves the reception power.

This paper presents a double extension of the mathematical Weyl group with the purpose of increas... more This paper presents a double extension of the mathematical Weyl group with the purpose of increasing the spectral efficiency of the Differential Space-Time Modulation (DSTM) scheme using this group of matrices. The error performance of the system is improved through an optimal selection of the matrices selected for a given spectral efficiency and an optimal mapping between the binary data vectors and the information matrices. Finally, the performance of the obtained system is evaluated using a more realistic time-varying channel model.

2017 Sensors Networks Smart and Emerging Technologies (SENSET), Sep 1, 2017

This paper presents a microwave system for measuring the cardiopulmonary activity performed in tw... more This paper presents a microwave system for measuring the cardiopulmonary activity performed in two ways: by using single antenna and by using two antennas. This system generates a continuous wave signal at 20 GHz toward the target and then measure the reflected signal. The target is the person's chest set placed at a distance of 1 m. The VNA measures the phase variation between the emitted and received signals. This phase variation contains information about the movement of the chest. An electrocardiograph is used simultaneously with the system as reference in order to determine the accuracy of the VNA system. The measurements are performed for a person under two conditions: breathing normally and holding the breath. Wavelet transform is used for the processing the obtained signals and the heartbeat rate is extracted accurately.

HAL (Le Centre pour la Communication Scientifique Directe), May 14, 2019

-Cet article présente les premiers résultats de l'étude de propagation dans la bande de 60 GHz, p... more -Cet article présente les premiers résultats de l'étude de propagation dans la bande de 60 GHz, prévue pour les nouveaux réseaux locaux sans fil. L'étude repose sur deux campagnes de mesures menées dans un environnement indoor. Les résultats permettent de modéliser les pertes de puissance en fonction de la distance pour différentes configurations. Par ailleurs, l'étude de la réponse impulsionnelle du canal permet de mettre en évidence la propagation par trajets multiples.

International Journal on Communications Antenna and Propagation, Jun 30, 2016

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

HAL (Le Centre pour la Communication Scientifique Directe), Aug 7, 2008

This paper presents a brief overview of several studies concerning the indoor wireless communicat... more This paper presents a brief overview of several studies concerning the indoor wireless communications at 60 GHz performed by the IETR. The characterization and the modeling of the radio propagation channel are based on several measurement campaigns realized with the channel sounder developed at IETR. Some typical residential environments were also simulated by ray tracing and Gaussian Beam Tracking. The obtained results show a good agreement with the similar experimental results. Currently, the IETR is developing a high data rate wireless communication system operating at 60 GHz. The single-carrier architecture of this system is also presented.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 23, 2015

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

HAL (Le Centre pour la Communication Scientifique Directe), Feb 4, 2009

International audienc

This paper presents characterization measurements of the dynamic propagation channel at 60 GHz in... more This paper presents characterization measurements of the dynamic propagation channel at 60 GHz in an indoor office-type environment. These measurements quantify the influence of the access point (AP) location in the presence of natural people movements. They were performed using a vector network analyzer (VNA) operating on 2 GHz bandwidth. 9900 measures of the channel frequency response were recorded over eleven hours for each receiver position. Five receiver positions were considered in line-of-sight (LOS). The obtained results allow to compute the channel path loss (PL). For each receiver location, the experimental probability distribution function (PDF) and the cumulative distribution function (CDF) of PL values were also computed and analyzed. Analysis shows that the location of the access point can have a strong impact on the quality of the radio link.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 1, 2003

ABSTRACT

2022 16th European Conference on Antennas and Propagation (EuCAP)

2019 International Conference on Wireless and Mobile Computing, Networking and Communications (WiMob)

In this work, we present a propagation measurements campaign conducted at 60 GHz in a typical ind... more In this work, we present a propagation measurements campaign conducted at 60 GHz in a typical indoor office environment. These measurements can be useful in order to exploit multipaths, aiming to maintain the quality of the communication in the case of blocking the direct path due to an obstruction created by people, furniture or other obstacles. The measurements were realized on 2 GHz bandwidth using a vector network analyzer (VNA). At the receiving side being always visible by the transmitter, a rotation by 6 • over 360 • is performed. The obtained results allow to compute different channel parameters such as: path loss, RMS delay spread and coherence bandwidth. In our study, we consider for each receiver position two situations: the direct orientation and the best indirect orientation of the receiving antenna. These results show that the path loss of the best indirect orientation increases up to 18 dB compared to the direct orientation. Indeed, some positions may be more affected than others in the case of blocking the direct orientation. The obtained results will be useful both to design the new broadband communication systems and to deploy wireless local and personal area networks (WLAN/WPAN) operating in the millimeter-wave (mmWave) bands. Index Terms-60 GHz, indoor radio channel, measurements, VNA, path loss, RMS delay spread, coherence bandwidth, angle of arrival

2021 IEEE Conference on Antenna Measurements & Applications (CAMA), 2021

This paper presents the characterization of the propagation channel at 60 GHz in a meeting room. ... more This paper presents the characterization of the propagation channel at 60 GHz in a meeting room. This characterization was done using measurements and simulations. From measurements we provide the angular received power and the path loss using a vector network analyzer (VNA) operating on 2 GHz bandwidth. In simulations, we use ray tracing technique trying to respect the same measurements conditions, in order to obtain comparable results. Finally, we compare the measurement and simulation results in direct orientation (DO) and in best indirect orientation (BIO). This will be useful for designing beamforming techniques for future millimeter communication systems.

2019 International Symposium on Signals, Circuits and Systems (ISSCS), 2019

This paper presents the results obtained from 60 GHz propagation measurement campaigns in indoor ... more This paper presents the results obtained from 60 GHz propagation measurement campaigns in indoor environments. These measurements are performed in the frequency domain and are based on the use of a vector network analyzer (VNA). The analysis of the results makes it possible to characterize the propagation channel. In first measurement campaign, we show the influence of different types of antennas on the path loss characteristics in a hallway, while in the second campaign results highlight the effect of the type of antenna of the access point (AP) and its position on the angular impulse response of the channel inside a meeting room. All of these results are intended to lead to rules for the deployment of wireless high-speed local and personal area networks (WLANs/WPANs).

This paper presents different signal processing techniques used in separating cardiopulmonary sig... more This paper presents different signal processing techniques used in separating cardiopulmonary signals measured using a microwave Doppler radar. For different sides from the person under test, the microwave system is tested for several operational frequencies simultaneously with a PC-based electrocardiograph. Wavelet transforms are used in order to separate heartbeat signal from the cardiopulmonary signals. High accuracy is obtained in terms of heartbeat rate for the whole measurements.

2020 14th European Conference on Antennas and Propagation (EuCAP), 2020

In this work, we study the dynamic 60 GHz radio propagation channel conducted by measurements in ... more In this work, we study the dynamic 60 GHz radio propagation channel conducted by measurements in an open-space office. These measurements quantify the effect of natural people movements on the path loss before and during working hours. Thus, it’s possible to compare the effect produced by these movements with the static case when the office is empty of people. Measurements were performed using a vector network analyzer (VNA) operating on 2 GHz bandwidth. 9900 measures of power loss were recorded over eleven hours of measurements for each receiver position. Five receiver positions were considered to study three cases of receiver positions type: the line-of-sight (LOS), the obstructed-line-of-sight (OLOS) and the non-line-of-sight (NLOS). The obtained results allow to compute successively the channel path loss (PL), its probability density function (PDF) and its cumulative distribution function (CDF). Finally we compare the evolution of the dynamic channel in the presence of people at...

2016 IEEE Middle East Conference on Antennas and Propagation (MECAP), 2016

This paper presents a wireless measurement system for cardiopulmonary activity detection behind a... more This paper presents a wireless measurement system for cardiopulmonary activity detection behind a wall. This system generates a continuous wave signal and is used at 2 different frequencies: 2.4 GHz and 10 GHz. The transmitted signal is directed toward the patient's chest situated at 1 m and then reflected. The radar system is based on a vector network analyzer, which measures the phase of S 21. The phase variation of S 21 contains information about heart and respiration activity. Measurements are carried out every 30 seconds, for a person sitting at a distance of 1 meter, directly in front of the system or behind a wall. Discrete wavelet transform is used as a processing technique to separate heartbeat signal from respiratory signal. The measurements were performed simultaneously with a PCbased electrocardiogram (ECG) which is used as a reference to validate the information extracted from the measured signals.

Advanced Biosignal Processing and Diagnostic Methods, 2016

As traditional electrodes are perturbing for patients in critical cases such as for burn victims ... more As traditional electrodes are perturbing for patients in critical cases such as for burn victims or newborn infants, and even to detect life sign under rubble, a contactless monitoring system for the life signs is a necessity. The aim of this chapter is to present a complete process used in detecting cardiopulmonary activities. This includes a microwave Doppler radar system that detects the body wall motion and signal processing techniques in order to extract the heartbeat rate. Measurements are performed at different positions simultaneously with a PC-based electrocardiogram (ECG). For a distance of 1 m between the subject and the antennas, measurements are performed for breathing subject at four positions: front, back, left, and right. Discrete wavelet transform is used to extract the heartbeat signal from the cardiopulmonary signal. The proposed system and signal processing techniques show high accuracy in detecting the cardiopulmonary signals and extracting the heartbeat rate.

HAL (Le Centre pour la Communication Scientifique Directe), Mar 1, 2003

At millimeter-waves, the home furniture and objects dimensions can be equal or superior to the wa... more At millimeter-waves, the home furniture and objects dimensions can be equal or superior to the wavelength. A comparison between propagation measurements conducted within a residential house for two configurations, furnished and empty, underscores the influence of the furniture on the millimeter-waves propagation.

arXiv (Cornell University), Dec 16, 2021

In the current development of new technologies, the world of communications is experiencing signi... more In the current development of new technologies, the world of communications is experiencing significant growth thanks to the integration of wireless communications in millimeter band. In this context, the purpose of this paper is to assess the contribution that the use of a metallic reflector panel can introduce to indoor radio coverage at 60 GHz in an NLOS (corridor) configuration. The results obtained by measurement show that the use of such a panel can lead to a significant path loss reduction up to 12 dB, which improves the reception power.