On the Feasibility of 5G Slice Resource Allocation With Spectral Efficiency: A Probabilistic Characterization

An important concern that 5G networks face is supporting a wide range of services and use cases with heterogeneous requirements. Radio access network (RAN) slices, understood as isolated virtual networks that share a common infrastructure, are a possible answer to this very demanding scenario and enable virtual operators to provide differentiated services over independent logical entities. This article addresses the feasibility of forming 5G slices, answering the question of whether the available capacity (resources) is sufficient to satisfy slice requirements. As spectral efficiency is one of the key metrics in 5G networks, we introduce the minislot-based slicing allocation (MISA) model, a novel 5G slice resource allocation approach that combines the utilization of both complete slots (or physical resource blocks) and mini-slots with the adequate physical layer design and service requirement constraints. We advocate for a probabilistic characterization that allows to estimate feasibility and characterize the behavior of the constraints, while an exhaustive search is very computationally demanding and the methods to check feasibility provide no information on the constraints. In such a characterization, the concept of phase transition allows for the identification of a clear frontier between the feasible and infeasible regions. Our method relies on an adaptation of the Wang-Landau algorithm to determine the existence of, at least, one solution to the problem. The conducted simulations show a significant improvement in spectral efficiency and feasibility of the MISA approach compared to the slot-based formulation, the identification of the phase transition, and valuable results to characterize the satisfiability of the constraints.The work of J. J. Escudero-Garzás was supported in part by the Spanish National Project TERESA-ADA (MINECO/AEI/FEDER, UE) under Grant TEC2017-90093-C3-2-R, and in part by the National Spectrum Consortium, USA, under Project NSC-16-0140

An energy-efficient adaptive modulation suitable for wireless sensor networks with SER and throughput constraints

We consider the problem of minimizing transmission energy in wireless sensor networks by taking into account that every sensor may require a different bit rate and reliability according to its particular application. We propose a cross-layer approach to tackle such a minimization in centralized networks for the total transmission energy consumption of the network: in the physical layer, for each sensor the sink estimates the channel gain and adaptively selects a modulation scheme; in the MAC layer, each sensor is correspondingly assigned a number of time slots. The modulation level and the number of allocated time slots for every sensor are constrained to attain their applications bit rates in a global energy-efficient manner. The signal-to-noise ratio gap approximation is used in our exposition in order to jointly handle required bit rates, transmission energies, and symbol error rates.This work has been partially funded by CRUISE NoE (IST-4-027738), MAMBO2 (CCG06-UC3M/TIC-0698) and MACAWI (TEC- 2005-07477-C02-02) projects.Publicad

Human activities and inundation risks in the plain of the Guadalquivir River (in the reach between Palam del Río and Seville)

Se presenta la ocupación antrópica de la llanura de inundación del Guadalquivir desde época histórica. Con ello se pone de manifiesto la falta de una planificación integrada frente al riesgo de inundación de la misma desde mediados del siglo XX hasta la actualidad. Esta situación genera cambios geomorfológicos irreversibles en el cauce y un comportamiento diferenciado en el riesgo potencial de inundación. En la ciudad de Sevilla, las intervenciones estructurales unidas a la incisión del cauce permiten evacuar las crecidas para magnitudes inferiores a 3.500 m3/s. Aguas arriba de Cantillana, la colmatación del cauce vinculada a la presa, la convergencia de afluentes regulados y la expansión urbana, provocan en la actualidad riesgos de inundación en zonas históricamente no inundables para estos caudales.We present the anthropic occupation of the flood plains of the Guadalquivir River from historic times. With it, we illustrate the lack of an integrated plan that would defend it from the risk of a flood from the middle of 20th century until today. This situation creates irreversible geomorphological changes in the riverbed and a differentiated behavior in the potential risk of flooding. In Seville, the structural works together with the incision of the riverbed permit the draining of the flooding of magnitudes lower than 3.500 m3/s. Up the river from Cantillana, the filling of the riverbed linked to the damn, the confluence of the regulated tributaries and the urban spreading, provoke today risks of floods in historically non-floodable areas for these water flows

A Cholinergic Synaptically Triggered Event Participates in the Generation of Persistent Activity Necessary for Eye Fixation

An exciting topic regarding integrative properties of the nervous system is how transient motor commands or brief sensory stimuli are able to evoke persistent neuronal changes, mainly as a sustained, tonic action potential firing. A persisting firing seems to be necessary for postural maintenance after a previous movement. We have studied in vitro and in vivo the generation of the persistent neuronal activity responsible for eye fixation after spontaneous eye movements. Rat sagittal brainstem slices were used for the intracellular recording of prepositus hypoglossi (PH) neurons and their synaptic activation from nearby paramedian pontine reticular formation (PPRF) neurons. Single electrical pulses applied to the PPRF showed a monosynaptic glutamatergic projection on PH neurons, acting on AMPA-kainate receptors. Train stimulation of the PPRF area evoked a sustained depolarization of PH neurons exceeding (by hundreds of milliseconds) stimulus duration. Both duration and amplitude of this sustained depolarization were linearly related to train frequency. The train-evoked sustained depolarization was the result of interaction between glutamatergic excitatory burst neurons and cholinergic mesopontine reticular fibers projecting onto PH neurons, because it was prevented by slice superfusion with cholinergic antagonists and mimicked by cholinergic agonists. As expected, microinjections of cholinergic antagonists in the PH nucleus of alert behaving cats evoked a gaze-holding deficit consisting of a re-centering drift of the eye after each saccade. These findings suggest that a slow, cholinergic, synaptically triggered event participates in the generation of persistent activity characteristic of PH neurons carrying eye position signals.Unión Europea Grants BI04-CT98-0546España, Ministerio de Ciencia PB98-0011, BFI2000-00936, BFI2000-1190, y BFI2002-0137

Multi-Sensor Accurate Forklift Location and Tracking Simulation in Industrial Indoor Environments

[Abstract] Location and tracking needs are becoming more prominent in industrial environments nowadays. Process optimization, traceability or safety are some of the topics where a positioning system can operate to improve and increase the productivity of a factory or warehouse. Among the different options, solutions based on ultra-wideband (UWB) have emerged during recent years as a good choice to obtain highly accurate estimations in indoor scenarios. However, the typical harsh wireless channel conditions found inside industrial environments, together with interferences caused by workers and machinery, constitute a challenge for this kind of system. This paper describes a real industrial problem (location and tracking of forklift trucks) that requires precise internal positioning and presents a study on the feasibility of meeting this challenge using UWB technology. To this end, a simulator of this technology was created based on UWB measurements from a set of real sensors. This simulator was used together with a location algorithm and a physical model of the forklift to obtain estimations of position in different scenarios with different obstacles. Together with the simulated UWB sensor, an additional inertial sensor and optical sensor were modeled in order to test its effect on supporting the location based on UWB. All the software created for this work is published under an open-source license and is publicly available.Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED431G/01Agencia Estatal de Investigación de España; TEC2016-75067-C4-1-

Environmental Cross-Validation of NLOS Machine Learning Classification/Mitigation with Low-Cost UWB Positioning Systems

[Abstract] Indoor positioning systems based on radio frequency inherently present multipath-related phenomena. This causes ranging systems such as ultra-wideband (UWB) to lose accuracy when detecting secondary propagation paths between two devices. If a positioning algorithm uses ranging measurements without considering these phenomena, it will face critical errors in estimating the position. This work analyzes the performance obtained in a localization system when combining location algorithms with machine learning techniques applied to a previous classification and mitigation of the propagation effects. For this purpose, real-world cross-scenarios are considered, where the data extracted from low-cost UWB devices for training the algorithms come from a scenario different from that considered for the test. The experimental results reveal that machine learning (ML) techniques are suitable for detecting non-line-of-sight (NLOS) ranging values in this situation.Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED431G/01Agencia Estatal de Investigación de España; TEC2016-75067-C4-1-

NLOS Identification and Mitigation Using Low-Cost UWB Devices

[Abstract] Indoor location systems based on ultra-wideband (UWB) technology have become very popular in recent years following the introduction of a number of low-cost devices on the market capable of providing accurate distance measurements. Although promising, UWB devices also suffer from the classic problems found when working in indoor scenarios, especially when there is no a clear line-of-sight (LOS) between the emitter and the receiver, causing the estimation error to increase up to several meters. In this work, machine learning (ML) techniques are employed to analyze several sets of real UWB measurements, captured in different scenarios, to try to identify the measurements facing non-line-of-sight (NLOS) propagation condition. Additionally, an ulterior process is carried out to mitigate the deviation of these measurements from the actual distance value between the devices. The results show that ML techniques are suitable to identify NLOS propagation conditions and also to mitigate the error of the estimates when there is LOS between the emitter and the receiver.Xunta de Galicia; ED431C 2016-045Xunta de Galicia; ED431G/01Agencia Estatal de Investigación de España; TEC2016-75067-C4-1-

Design of 300 ghz combined doubler/subharmonic mixer based on schottky diodes with integrated mmic based local oscillator

In this paper the design and experimental characterization of a combined doublersubharmonic mixer based on Schottky diodes which uses a 75 GHz MMIC based local oscillator is presented. This solution integrates in the same substrate the doubler and the mixer, which share the same metallic packaging with the local oscillator. The prototype has been fabricated and measured. For characterization, the Y-Factor technique has been used and the prototype yields a best conversion loss and equivalent noise temperature of 11 dB and 1976 K, respectively, at 305 GHz. This performance is close to the state of the art, and shows the potential of this approach, which allows a significant reduction in terms of size and volume.This research was funded by the Spanish MINECO, Project No. TEC2016-76997-C3-1-R, and by the Spanish State Research Agency, Project No. PID2019-109984RB-C43/AEI/10.13039/501100011033