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Khalighi M.-A.,Ecole Centrale Marseille | Helard J.-F.,Institute Delectronique Et Of Telecommunications Of Rennes | Sadough S.M.-S.,Shahid Beheshti University | Bourennane S.,Ecole Centrale Marseille
AEU - International Journal of Electronics and Communications

In order to propose practical solutions for future communication systems employing a combination of multiple-input multiple-output (MIMO) structures and orthogonal frequency division multiplexing (OFDM), we analyse and compare the performances obtained by orthogonal and non-orthogonal space-time coding schemes. A simple iterative detector based on soft parallel interference cancellation (Soft-PIC) is used in the receiver in order to cope with the interference terms when using non-orthogonal schemes. First, we propose a modification of the log-likelihood ratio (LLR) calculation part in the Soft-PIC detector that provides an improvement of the receiver performance compared to previous implementations of this detector. Then, the performances of different space-time schemes proposed for two, three or four antennas at the transmitter and two antennas at the receiver are compared. In the case of perfect channel estimation, a substantial gain is obtained by using the appropriate non-orthogonal schemes for moderate-to-high spectral efficiency MIMO systems, which justifies the increased complexity of the receiver. This conclusion is conditioned to the presence of sufficient frequency diversity that is the case in a practical system. We also study the case of imperfect channel estimation at the receiver and discuss the choice of the appropriate space-time scheme. The gain offered by the non-orthogonal schemes is confirmed in that case, specifically for high spectral efficiency systems. © 2009 Elsevier GmbH. All rights reserved. Source

El-Makhour R.,EMC Laboratory | De-Daran F.,EMC Laboratory | Lafon F.,EMC Laboratory | Drissi M.,Institute Delectronique Et Of Telecommunications Of Rennes | Fourn E.,Institute Delectronique Et Of Telecommunications Of Rennes
2010 Asia-Pacific Symposium on Electromagnetic Compatibility, APEMC 2010

This paper presents a modelling technique that predicts the detuning of a RF (Radio Frequency) receiver ahead of its installation into a vehicle. In fact, since the vehicle is rarely available during the equipment's development phase, it becomes necessary to finalise the product even before it can be tested in its operational environment. The proposed model is based on a circuit approach which permits a fast evaluation of the resonant frequency shifting. The comparison with a 3D full wave simulation confirms the robustness of the proposed technique. © 2010 IEEE. Source

Toutin T.,Canada Center For Remote Sensing | Wang H.,Canada Center For Remote Sensing | Chomaz P.,National School of Geographic Sciences | Pettier E.,Institute Delectronique Et Of Telecommunications Of Rennes
International Geoscience and Remote Sensing Symposium (IGARSS)

Ortho-rectification using digital terrain models is a key issue for full polarimetric complex synthetic aperture radar (SAR) data because resampling the complex data can corrupt the polarimetric phase, mainly in study sites with relief. This research thus compared two approaches for the ortho-rectification of the complex SAR data: the polarimetric processing is performed before (scientist approach) or after (user approach) the geometric processing. A quantitative evaluation between the two approaches as a function of different geometric and radiometric parameters was thus performed to quantify the impact of the ortho-rectification on the complex polarimetric SAR. Radarsat-2 fine-quad data acquired over a rolling relief study site were geometrically processed using a lidar digital surface model. The evaluation results showed than the terrain slopes and land covers can potentially corrupt the polarimetric complex SAR data during the ortho-rectification. Advices are finally provided to reduce these impacts to an acceptable level for the users and their applications. Preliminaries results of simulated compact polarimetric SAR data of the new Canadian Radar Constellation Mission will be presented at the Conference. © 2012 IEEE. Source

Llorente R.,Polytechnic University of Valencia | Morant M.,Polytechnic University of Valencia | Amiot N.,Institute Delectronique Et Of Telecommunications Of Rennes | Uguen B.,Institute Delectronique Et Of Telecommunications Of Rennes
European Conference on Optical Communication, ECOC

A time-multiplexed multichannel photonic-ADC is proposed and demonstrated for the detection and localisation of ultra-wideband radio transmitters. The experimental results indicate successful operation with a mean positioning error of 0.9 m. ©2010 IEEE. Source

Bor J.,Institute Delectronique Et Of Telecommunications Of Rennes | Lafond O.,Institute Delectronique Et Of Telecommunications Of Rennes | Fuchs B.,Institute Delectronique Et Of Telecommunications Of Rennes | Merlet H.,Canon Inc. | And 2 more authors.
8th European Conference on Antennas and Propagation, EuCAP 2014

The control of dielectric constant is an important issue in the design of many microwave antenna systems such as gradient index lens antennas. An innovative technological process has been developed to easily manufacture dielectric based antenna systems and microwave components from the use of foam material. This process is cheap and easy to implement. It has been applied to design a flat Luneburg lens from one single foam material. The good agreement between simulations and measurements of the lens antenna between 57 and 65 GHz validate the proposed technology. © 2014 European Association on Antennas and Propagation. Source

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