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Massive multiple-input multiple-output (MIMO) is considered as one of the building blocks of 5G. This technology offers higher capacity, faster speed and improved spectral and energy efficiency. In this paper, we investigate massive MIMO propagation channel performances in real propagation environment. Therefore, channel measurements were carried out at 3.7 GHz using a uniform planar array (UPA) with 64 elements as a receiver and a patch array made of 8 elements PIFA as a transmitter. Both line-of-sight (LoS) and non-line-of-sight (NLoS) conditions were investigated in this campaign. Additionally, simulations using Orange ray-based 3D propagation model termed as Starlight were conducted. The objective is to characterize both measured and simulated Massive MIMO channels and optimize this propagation model to ensure agreement between simulations and measurements.

This PhD thesis concerns a range of technological studies and physical applications within the fields of ultrafast science and coherent control. From the technological point of view, we have performed a comprehensive study of space-time coupling within the 'Dazzler' AOPDF pulse shaper using interferometric techniques. For a while such limitations of '4f' zero-dispersion line pulse shapers have been widely documented; our results were the first to demonstrate, quantify and explain a parallel effect in this alternative device. From a control perspective, we have demonstrated exciting results about temporal refocusing of a broadband pulse that has been strongly distorted by a random, multiply scattering medium (i.e. the temporal analogue of the spatial speckle pattern). For this purpose a spatially resolved measurement of the spectral phase of the distorted pulse followed by open-loop feedback to a pulse shaper were implemented: as a result of the linearity of the scattering process, this pre-compensation has led to a spatially localized flat output spectral phase and hence a short pulse. This has already stimulated much interest amongst colleagues for diverse applications such as biological imaging or quantum optics studies.; Cette thèse porte sur une série d'études technologiques et d'applications physiques dans les domaines de la dynamique ultrarapide et contrôle cohérent. Du point de vue technologique, nous avons effectué une étude approfondie de couplage spatio-temporel induit par l'interaction de l'onde optique avec une onde acoustique au sein d'un cristal non linéaire pour le façonnage de l'impulsion laser ultra courte. Cette étude a été menée en utilisant des techniques interférométriques. Ces effets bien connus dans les façonneurs d'impulsions utilisant une ligne 4f n'avaient jamais été mesurés dans ce type façonneur. Nos résultats ont été les premiers à les démontrer, les quantifier et les expliquer. Du point de vue du contrôle, nous avons mis en évidence des résultats très intéressants concernant la refocalisation temporelle d'une impulsion large bande fortement perturbée par un milieu multi-diffusif (i.e. l'analogue temporel de speckle spatiale). Pour cela nous avons d'eveloppé une mesure résolue spatialement de la phase spectrale de l'impulsion déformée suivie par une rétroaction en boucle ouverte permettant la correction en temps réelle de la phase grâce à un façonneur d'impulsions: en raison de la linéarité du processus de diffusion, cette compensation a permis de réaliser la recompression d'une impulsion laser en sortie de l''echantillon en un point donné (localisation spatiale) . Cela a suscité beaucoup d'intérêts parmi les collègues pour diverses applications telles que l'imagerie biologique ou pour des développements utilisant l'optique quantique.

In this paper, we present a new approach of analysis and recognition of retinal vessel segments for the quantification of their shapes change due to alterations. This approach is based on a spatial followed by a temporal characterization of retinal fluorescein angiographic images. The spatial characteristics (coordinates and classification number i.e. numbering of segments) are associated to bifurcation points (bp), which are matched in temporal image pairs for vessel segments correspondence forming. The matching process uses spatial and temporal characteristics between the bp and their surrounded vessel segments by computing a coefficient of similarity measurement.The recognition of vessel segments will help ophthalmologists in quantifying changes in vessel shape parameters and detect the temporal evolution of some retinal pathologies as the Sickle Cell retinopathy in our case.