Oscar Rubiños

Analysis of Unicast Routing Protocols for VANETs

A mobile ad hoc network (MANET) is a kind of self-configuring ad hoc network of mobile routers connected by wireless links. Vehicular Ad Hoc Networks (VANETs) are MANETs used for communication among vehicles, and between vehicles and roadside equipment. In order to create a new routing protocol applied to car-to-car networks, we define some parameters to evaluate the efficiency of some of the existing routing protocols. The 802.11p technology designed for VANET was also used, applying the overhaul implementation, which improves the physical and medium access control layer. Our aim is to obtain routing evaluation parameters to be used in a platform between Simulation of Urban Mobility and Network Simulator. We will use these simulations for the implementation and testing of our own geocast routing protocol meant to send information to other vehicles situated in a given geographical position.

3-D High-Resolution Imaging Radar at 300 GHz With Enhanced FoV

We have developed a 3-D high-resolution radar at 300 GHz with a cell resolution of 1×1.6×1.6 cm3 at a standoff distance of 8 m for security applications. The selection of an operating frequency of 300 GHz, a bandwidth of 27 GHz, and a field of view of 50×90 cm2 improves the through-clothes imaging of person-borne concealed objects. The radars antenna design allows single-pixel imaging at a frame rate of two frames per second. A reduction in cost and power consumption and improvements in image quality are additional requirements taken into account in the design of this radar system.

Bootstrap approaches for spatial data

Generation of replicates of the available data enables the researchers to solve different statistical problems, such as the estimation of standard errors, the inference of parameters or even the approximation of distribution functions. With this aim, Bootstrap approaches are suggested in the current work, specifically designed for their application to spatial data, as they take into account the dependence structure of the underlying random process. The key idea is to construct nonparametric distribution estimators, adapted to the spatial setting, which are distribution functions themselves, associated to discrete or continuous random variables. Then, the Bootstrap samples are obtained by drawing at random from the estimated distribution. Consistency of the suggested approaches will be proved by assuming stationarity from the random process or by relaxing the latter hypothesis to admit a deterministic trend. Numerical studies for simulated data and a real data set, obtained from environmental monitoring, are included to illustrate the application of the proposed Bootstrap methods.

Bifocal Reflector Antenna for a Standoff Radar Imaging System With Enhanced Field of View

A unique multireflector bifocal antenna design for real-time standoff imaging applications is presented in this work. The antenna is used in combination with a 300 GHz radar sensor to acquire images at 8 m over a large (80 × 50 cm) field of view (FoV). The increased FoV is obtained by the use of an antenna system composed by a bifocal elliptical Gregorian with an extended subreflector to allow for fast scanning of a beam spot. The scanning is achieved by the combination of the rotation and vertical tilting of a flat small secondary mirror. The design, simulations, prototype description and experimental results of a manufactured working prototype are presented.

Active Safety Evaluation in Car-to-Car Networks

Currently, the main purpose in car-to-car networks is to improve communication performance. In order to prove this, we need a tool to evaluate statistical values such as the number of vehicles that have received the information, time of reception of the message, etc. In this study, we demonstrate how it is possible to simulate real scenarios with car-to-car technology and evaluate all traffic parameters obtained in simulations with hundreds of vehicles that receive alert signals for specific events. We will simulate one traffic accident both in a highway and in a urban scenario with different traffic patterns and we will analyze how data are received by the cars that are located in the coverage range. Thus, we can know the topology deficiencies in certain situations and in which situations, for example, it is possible to provide Road Side Units (RSU) or Public Hot Spot (PHS) units to perform network messages.

Design and preliminary results of a ground-based cloud profiling radar at 94 GHz

This paper describes a 94-GHz ground-based CW-LFM radar system for cloud monitoring. This system transmits 1 W and the bandwidth is configurable up to 2000 MHz. A two-antenna configuration is used to improve the Tx-Rx isolation and two different antennas are used to avoid parallax errors. An RF characterization of the radar architecture is presented. Lastly, a drone detection experiment and preliminary cloud measurements are carried out to validate the radar operation.

Optimization of a compact THz imaging radar for real-time operation

A summary of obstacles and solutions in the Universidad Politécnica de Madrids CW-LFM (continuous-wave linear frequency modulation) imaging radar towards enabling real-time through-clothes threat detection with a compact system is presented. Image acquisition has been designed to permit a 2 fps (frames per second) video feed, and a newly developed signal-processing and image representation software, run on a mixed CPU-GPGPU (central processing unit general-purpose graphics processing unit) architecture, allows speeds up to 5 fps. Additional hardware modifications have yielded reductions in cost, power consumption, and volume.

A dual reflector antenna with adjustable subreflector for hybrid mechanical-electronic scanning

This paper presents some results of the ESA project ¿Hybrid Mechanical-Electronic Pointing System¿, which considers future scenarios using the Q/V band on satellite communications. The main characteristic of the antenna is to provide two separate controls of the main beam: electronic control and mechanical control. The mechanical control is produced by an adjustable subreflector, working cooperatively with the electronic beam control provided by a source array as primary feed of the antenna system. A Gregorian Confocal configuration has been adopted. The subreflector design has been developed under Geometrical Optics approximation and Simulated Annealing optimization techniques to provide best-fit-paraboloidal representations of the surface that can be implemented with a limited number of mechanical actuators.

Understanding cloud dynamics using a ground-based radar at 94 GHz

This paper presents the analysis of mixed-phase cloud observations in Madrid (Spain) carried out with a 94-GHz ground-based CW-LFM radar system. This analysis is based on the 3D reflectivity profiles and the Doppler spectra. The case of interest occurred on 29th January 2016 when a melting layer at 1 Km, up- and downdrafts and drizzle were detected. This radar can be used to estimate the microphysical composition of the detected mixed-phase clouds.