ML approaches to channel estimation for pilot-aided multi-rate DS/CDMA systems

This paper analyzes the asymptotic performance of maximum likelihood (ML) channel estimation algorithms in wideband code division multiple access (WCDMA) scenarios. We concentrate on systems with periodic spreading sequences (period larger than or equal to the symbol span) where the transmitted signal contains a code division multiplexed pilot for channel estimation purposes. First, the asymptotic covariances of the training-only, semi-blind conditional maximum likelihood (CML) and semi-blind Gaussian maximum likelihood (GML) channelestimators are derived. Then, these formulas are further simplified assuming randomized spreading and training sequences under the approximation of high spreading factors and high number of codes. The results provide a useful tool to describe the performance of the channel estimators as a function of basicsystem parameters such as number of codes, spreading factors, or traffic to training power ratio.

Desarrollo de aplicaciones moviles con HTML5: Audioguia turistica del Real Monasterio San Lorenzo de El Escorial

Este trabajo ha tenido como objetivo la realización de una aplicación para móviles desarrollada en HTML5 llamada ¿Audioguía Turística de El Real Monasterio de San Lorenzo de El Escorial¿.Se han utilizado tecnologías como HTML5, javascript, jQuery Mobile (framework de javascritp), CSS, ThemRoller, y Phonegap (ahora apache Cordoba). También se ha usado Eclipse como IDE para el desarrollo con el pluging de Aptana.Se ha logrado una aplicación instalable en cualquier dispositivo móvil (Smartphone) o Tablet de cualquier tamaño, obteniéndose una app multidispositivo de tipo híbrida que puede usar y disponer de los recursos que posee el teléfono móvil como hacer llamadas, geolocalización, etc. Aparte de todo ello, para alcanzar una app multiplataforma se ha usado Phonegap Build, proporcionándonos con la compilación en la nube varios archivos instalables en distintas plataformas como Android, Windows-Phone, etc. Por tanto, se ha obtenido el desarrollo de una aplicación con HTML5 multidispositivo y multiplataforma.

Determinants of Broadband Access: Is Platform Competition always the Key Variable to Success?

Previous studies have identified the rivalry among technological platforms as one of the main driving forces of broadband services penetration. This paper draws on data from the Spanish market between 2005 and 2011 to estimate the main determinants of broadband prices. Controlling for broadband tariffs features and network variables, we examine the impact of the different modes of competition on prices. We find that inter-platform competition has no significant effects over prices, while intra-platform competition is a key driver of the prices charged in the broadband market. Our analysis suggests that the impact of different types of competition on prices is critically affected by the levels of development of the broadband market achieved by the considered country

Extension and evaluation of JXTA protocols for supporting reliable P2P distributed computing

Peer-reviewed

Efficient image mosaicing for multi-robot visual underwater mapping

Robotic platforms have advanced greatly in terms of their remote sensing capabilities, including obtaining optical information using cameras. Alongside these advances, visual mapping has become a very active research area, which facilitates the mapping of areas inaccessible to humans. This requires the efficient processing of data to increase the final mosaic quality and computational efficiency. In this paper, we propose an efficient image mosaicing algorithm for large area visual mapping in underwater environments using multiple underwater robots. Our method identifies overlapping image pairs in the trajectories carried out by the different robots during the topology estimation process, being this a cornerstone for efficiently mapping large areas of the seafloor. We present comparative results based on challenging real underwater datasets, which simulated multi-robot mapping