Achieving Large Multiplexing Gain in Distributed Antenna Systems via Cooperation with pCell Technology

In this paper we present pCellTM technology, the first commercial-grade wireless system that employs cooperation between distributed transceiver stations to create concurrent data links to multiple users in the same spectrum. First we analyze the per-user signal-to-interference-plus-noise ratio (SINR) employing a geometrical spatial channel model to define volumes in space of coherent signal around user antennas (or personal cells, i.e., pCells). Then we describe the system architecture consisting of a general-purpose-processor (GPP) based software-defined radio (SDR) wireless platform implementing a real-time LTE protocol stack to communicate with off-the-shelf LTE devices. Finally we present experimental results demonstrating up to 16 concurrent spatial channels for an aggregate average spectral efficiency of 59.3 bps/Hz in the downlink and 27.5 bps/Hz in the uplink, providing data rates of 200 Mbps downlink and 25 Mbps uplink in 5 MHz of TDD spectrum.Comment: IEEE Asilomar Conference on Signals, Systems, and Computers, Nov. 8-11th 2015, Pacific Grove, CA, US

Confirmation and Characterization of the Eccentric, Warm Jupiter TIC 393818343 b with a Network of Citizen Scientists

NASA’s Transiting Exoplanet Survey Satellite (TESS) has identified over 7000 candidate exoplanets via the transit method, with gas giants among the most readily detected due to their large radii. Even so, long intervals between TESS observations for much of the sky lead to candidates for which only a single transit is detected in one TESS sector, leaving those candidate exoplanets with unconstrained orbital periods. Here, we confirm the planetary nature of TIC 393818343 b, originally identified via a single TESS transit, using radial velocity data and ground-based photometric observations from citizen scientists with the Unistellar Network and Exoplanet Watch. We determine a period of P = 16.24921 −0.00011+0.00010 days, a mass M P = 4.34 ± 0.15 M J, and semimajor axis a = 0.1291 −0.0022+0.0021 au, placing TIC 393818343 b in the “warm Jupiter” population of exoplanets. With an eccentricity e = 0.6058 ± 0.0023, TIC 393818343 b is the most eccentric warm Jupiter to be discovered by TESS orbiting less than 0.15 au from its host star and therefore an excellent candidate for follow-up, as it may inform our future understanding of how hot and warm Jupiter populations are linked

Traitement du signal pour les communications optiques à haute efficacité spectrale

The research work presented in this dissertation deals with the application of modulation and digital signal processing techniques in the field of optical communications. It focuses on the design of a 40Gb/s short-reach optical transmission system. For a given optical wavelength, capacity increase is generally achieved by pushing technological limits in order to augment the serial line rate of simple on-off keying modulations. This approach is not compatible with the economics of high-capacity short-reach applications. The use of sub-carrier multiplexing with multilevel signaling reduces bandwidth occupation and signaling rate. Components taken from existing 10Gb/s systems can thus be used to transmit 40Gb/s. At reduced signaling rates, CMOS circuit technology can be exploited to integrate elaborate signal processing functions. The adaptive signal processing structures presented in this dissertation relax analog front-end design requirements. They can also compensate for linear impairments due to the channel as well as fabrication process variations. The system is analyzed by deriving theoretical and numerical models agreeing with experimental validation. Simulation results show that a low-cost 40Gb/s system reaching beyond 10km is indeed feasible. We present a system prototype based on a CMOS test chip implementing modulation/demodulation functions for the highest-frequency and most challenging RF channel. This transmission system prototype operates over more than 30km of single mode fiber.Les travaux de recherche présentés dans cette thèse s'intéressent à l'application de techniques de modulation et de traitement du signal numérique aux communications optiques. Ils se concentrent sur la conception d'un système de communication optique sur courte distance à 40Gb/s. Pour une longueur d'onde optique donnée, l'accroissement du débit binaire s'obtient généralement en repoussant les limites technologiques afin d'augmenter la vitesse des modulations simples du type "on-off keying". Cette méthode ne satisfait cependant pas les exigences économiques des applications à haut débit sur courte distance. La combinaison du multiplexage de porteuses électriques et d'une modulation à plusieurs niveaux permet de réduire le support fréquentiel et la vitesse de modulation du signal porteur d'information. Des composants typiques des systèmes de transmission à 10Gb/s peuvent ainsi être utilisés pour transmettre 40Gb/s. La technologie de circuits CMOS est également exploitable pour l'intégration économe de fonctions de traitement du signal élaborées. Les structures de traitement du signal adaptatives présentées permettent de réduire les exigences techniques dans la conception des fonctions analogiques. Elles permettent également de compenser les distorsions linéaires dues au canal de transmission et aux variations résultant d'une production industrielle. Des modèles théoriques et numériques validés par l'expérimentation permettent l'analyse du système. Les résultats de simulations numériques montrent qu'un système de communication à 40Gb/s à bas coût et d'une portée dépassant 10km est possible. Nous présentons également un prototype utilisant un circuit intégré test en technologie CMOS réalisant les fonctions de modulation/démodulation pour le canal RF le plus difficile à implémenter, et transmettant des données dans une fibre monomode s'étendant sur plus de 30km