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[EN] In this paper, we focus on the study of coupled systems of ordinary differential equations (ODEs) describing the diffusion of messages between mobile devices. Communications in mobile opportunistic networks take place upon the establishment of ephemeral contacts among mobile nodes using direct communication. SIR (Sane, Infected, Recovered) models permit to represent the diffusion of messages using an epidemiological based approach. The question we analyse in this work is whether the coexistence of a fixed infrastructure can improve the diffusion of messages and thus justify the additional costs. We analyse this case from the point of view of dynamical systems, finding and characterising the admissible equilibrium of this scenario. We show that a centralised diffusion is not efficient when people density reaches a sufficient value. This result supports the interest in developing opportunistic networks for occasionally crowded places to avoid the cost of additional infrastructure. ; This work was partially supported by Ministerio de Economia y Competitividad, Spain (Grants TEC2014-52690-R, MTM2016-75963-P & BCAM Severo Ochoa excellence accreditation SEV-2013-0323), Generalitat Valenciana, Spain (Grants AICO/2015/108, ACOMP/2015/005, GVA/2018/110), by the Basque Government through the BERC 2014-2017. ; Conejero, JA.; Hernández-Orallo, E.; Manzoni, P.; Murillo-Arcila, M. (2019). A SIR-based model for contact-based messaging applications supported by permanent infrastructure. Discrete and Continuous Dynamical Systems. Series S. 12(4-5):735-746. https://doi.org/10.3934/dcdss.2019048 ; S ; 735 ; 746 ; 12 ; 4-5

735 746 12 4-5 ; S ; [EN] In this paper, we focus on the study of coupled systems of ordinary differential equations (ODEs) describing the diffusion of messages between mobile devices. Communications in mobile opportunistic networks take place upon the establishment of ephemeral contacts among mobile nodes using direct communication. SIR (Sane, Infected, Recovered) models permit to represent the diffusion of messages using an epidemiological based approach. The question we analyse in this work is whether the coexistence of a fixed infrastructure can improve the diffusion of messages and thus justify the additional costs. We analyse this case from the point of view of dynamical systems, finding and characterising the admissible equilibrium of this scenario. We show that a centralised diffusion is not efficient when people density reaches a sufficient value. This result supports the interest in developing opportunistic networks for occasionally crowded places to avoid the cost of additional infrastructure. This work was partially supported by Ministerio de Economia y Competitividad, Spain (Grants TEC2014-52690-R, MTM2016-75963-P & BCAM Severo Ochoa excellence accreditation SEV-2013-0323), Generalitat Valenciana, Spain (Grants AICO/2015/108, ACOMP/2015/005, GVA/2018/110), by the Basque Government through the BERC 2014-2017. Conejero, JA.; Hernández-Orallo, E.; Manzoni, P.; Murillo-Arcila, M. (2019). A SIR-based model for contact-based messaging applications supported by permanent infrastructure. Discrete and Continuous Dynamical Systems. Series S. 12(4-5):735-746. https://doi.org/10.3934/dcdss.2019048

[EN] Mobile crowdsensing (MCS) is a technique where people with computing and sensing devices such as smartphones collectively share data that are of potential interest to the rest of society. MCS includes two different trends (i) mobile sensing, which shares raw data generated from the sensors that are embedded in mobile devices, and (ii) social sensing, which uses the information shared by people in online social networks (OSNs). In this study, the authors present the timeline evolution of the COVID¿19 pandemic in Spain, and summarise the MCS research efforts that are being undertaken by the Spanish community to address COVID¿19 outbreak. Indeed, the COVID¿19 pandemic is putting today's society at risk; lockdown and social distancing measures proposed by governments are dramatically affecting economies. In this regard, MCS tools can become a powerful solution to provide smart quarantine strategies in periods of a steep decrease of infections, or new outbreaks. ; This work was partially supported by the Fundación Séneca del Centro de Coordinación de la Investigación de la Región de Murcia under Project 20813/PI/18, and by the Spanish Ministry of Science, Innovation and Universities under grants RTI2018-096384-B-I00 and RTC-2017-6389-5. ; Cecilia-Canales, JM.; Cano, J.; Hernández-Orallo, E.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2020). Mobile crowdsensing approaches to address the COVID-19 pandemic in Spain. IET Smart Cities. 2(2):1-6. https://doi.org/10.1049/iet-smc.2020.0037 ; S ; 1 ; 6 ; 2 ; 2 ; World Health Organization:'Novel coronavirus (2019‐ncov): Situation report 91' [accessed 30‐April‐2020] ; Instituto de Salud.Carlos.III:'Situación de covid‐19 en españa' [accessed 30‐April‐2020].https://covid19.isciii.es/ ; LiR.RiversC.TanQ.et al.: 'The demand for inpatient and ICU beds for COVID‐19 in the US: lessons from Chinese cities' medRxiv 2020 pp.1–12 doi:10.1101/2020.03.09.20033241 ; World Health Organization:'Critical preparedness readiness and response actions for COVID‐19: interim guidance ...

©2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. ; In wireless community networks, backbone pointto-point links concentrate most of the traffic. Thus, these links are crucial for the overall performance of the network. Network managers have to constantly test and maintain these links to optimise their performance, but their decisions are often based upon rumours or a purely theoretical knowledge of the technologies being used. These sources of information can be very biased and can lead to incorrect decisions in such complex systems. In this work we provide the guidelines to help in wireless links optimization by covering the most common mistakes or questions, and by addressing the critical factors one by one using a real scenario. In our experiments we analyse critical characteristics such as the interference among links, the relation between channel bandwidth and throughput, the impact of output power, and the effect of antenna proximity. ; This work has been supported by project P1·1A2010-13 from the Universitat Jaume I, the project TIN2011-27543-C03-01 from "Ministerio de Ciencia e Innovación de España" and also by the ERDF of the European Union. ; Perez -Francisco, M.; Boronat-Perez, P.; Manzoni, P.; Tavares De Araujo Cesariny Calafate, CM.; Cano Escribá, JC. (2014). Rumours and Good Practices in Community Networks Wireless Links. IEEE COMMUNICATIONS SOCIETY. https://doi.org/10.1109/ICUFN.2014.6876822 ; S

(c) 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. ; [EN] In this paper, we propose a realistic model for simulating communications between unmanned aerial vehicles (UAVs), or drones, and ground vehicles, which can support mobile infrastructure to broadcast alerts in emergency situations. Three-dimensional positioning features should be considered in these simulations that involve UAVs and ground vehicles since communications links are not based on a flat surface. In fact, irregular terrains in the form of hills and mountains can greatly affect the communications by acting as obstacles that block radio signals partially or totally. Hence, in this paper, we propose a simulation model that conforms to this kind of communication and that was developed in the scope of the OMNeT++ simulator. The simulation results achieved showed a great degree of similarities with those results obtained in a real testbed for different scenarios. In addition, various path loss models and elevation models were considered to improve the level of realism of the simulation model. ; This work was supported in part by the Japan Society for the Promotion of Science KAKENHI under Grant JP16H02817 and Grant JP18KK0279, in part by the International Internship Program of the National Institute of Informatics, Japan, and in part by the Ministerio de Economía y Competividad, Programa Estatal de Investigación, Desarollo e Innovación Orientada a los Retos de la Sociedad, Proyectos ICDCI 2014, Government of Spain, under Grant TEC2014-52690-R and Grant BES-2015-075988. ; Hadiwardoyo, SA.; Tavares De Araujo Cesariny Calafate, CM.; Cano, J.; Ji, Y.; Hernández-Orallo, E.; Manzoni, P. (2019). 3D Simulation Modeling of UAV-to-Car Communications. IEEE ...

8808 8823 7 ; S ; (c) 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. [EN] In this paper, we propose a realistic model for simulating communications between unmanned aerial vehicles (UAVs), or drones, and ground vehicles, which can support mobile infrastructure to broadcast alerts in emergency situations. Three-dimensional positioning features should be considered in these simulations that involve UAVs and ground vehicles since communications links are not based on a flat surface. In fact, irregular terrains in the form of hills and mountains can greatly affect the communications by acting as obstacles that block radio signals partially or totally. Hence, in this paper, we propose a simulation model that conforms to this kind of communication and that was developed in the scope of the OMNeT++ simulator. The simulation results achieved showed a great degree of similarities with those results obtained in a real testbed for different scenarios. In addition, various path loss models and elevation models were considered to improve the level of realism of the simulation model. This work was supported in part by the Japan Society for the Promotion of Science KAKENHI under Grant JP16H02817 and Grant JP18KK0279, in part by the International Internship Program of the National Institute of Informatics, Japan, and in part by the Ministerio de Economía y Competividad, Programa Estatal de Investigación, Desarollo e Innovación Orientada a los Retos de la Sociedad, Proyectos ICDCI 2014, Government of Spain, under Grant TEC2014-52690-R and Grant BES-2015-075988. Hadiwardoyo, SA.; Tavares De Araujo Cesariny Calafate, CM.; Cano, J.; Ji, Y.; Hernández-Orallo, E.; Manzoni, P. (2019). 3D Simulation Modeling of UAV-to-Car ...

[EN] Recently, Unmanned Aerial Vehicles (UAVs) have become a cheap alternative to sense pollution values in a certain area due to their flexibility and ability to carry small sensing units. In a previous work, we proposed a solution, called Pollution-driven UAV Control (PdUC), to allow UAVs to autonomously trace pollutant sources, and monitor air quality in the surrounding area. However, despite operational, we found that the proposed solution consumed excessive time, especially when considering the battery lifetime of current multi-rotor UAVs. In this paper, we have improved our previously proposed solution by adopting a space discretization technique. Discretization is one of the most efficient mathematical approaches to optimize a system by transforming a continuous domain into its discrete counterpart. The improvement proposed in this paper, called PdUC-Discretized (PdUC-D), consists of an optimization whereby UAVs only move between the central tile positions of a discretized space, avoiding monitoring locations separated by small distances, and whose actual differences in terms of air quality are barely noticeable. We also analyze the impact of varying the tile size on the overall process, showing that smaller tile sizes offer high accuracy at the cost of an increased flight time. Taking into account the obtained results, we consider that a tile size of 100 x 100 meters offers an adequate trade-off between flight time and monitoring accuracy. Experimental results show that PdUC-D drastically reduces the convergence time compared to the original PdUC proposal without loss of accuracy, and it also increases the performance gap with standard mobility patterns such as Spiral and Billiard. ; This work was partially supported by the "Programa Estatal de Investigacion, Desarrollo e Innovacion Orientada a Retos de la Sociedad, Proyecto I+D+I TEC2014-52690-R", the framework of the DIVINA Challenge Team, which is funded under the Labex MS2T program. Labex MS2T is supported by the French Government, through the ...

Efficient message dissemination is of utmost importance to propel the development of useful services and applications in Vehicular ad hoc Networks (VANETs). In this paper, we propose a novel adaptive system that allows each vehicle to automatically adopt the most suitable dissemination scheme in order to fit the warning message delivery policy to each specific situation. Our mechanism uses as input parameters the vehicular density and the topological characteristics of the environment where the vehicles are located, in order to decide which dissemination scheme to use. We compare our proposal with respect to two static dissemination schemes (eMDR and NJL), and three adaptive dissemination systems (UV-CAST, FDPD, and DV-CAST). Simulation results demonstrate that our approach significantly improves upon these solutions, being able to support more efficient warning message dissemination in all situations ranging from low densities with complex maps, to high densities in simple scenarios. In particular, RTAD improves existing approaches in terms of percentage of vehicles informed, while significantly reducing the number of messages sent, thus mitigating broadcast storms. 2015 Elsevier B.V. All rights reserved. ; This work was partially supported by the Ministerio de Ciencia e Innovacion, Spain, under Grant TIN2011-27543-C03-01, as well as the Government of Aragon and the European Social Fund (T91 Research Group). ; Sanguesa, JA.; Fogue, M.; Garrido, P.; Martinez, FJ.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2015). RTAD: A real-time adaptive dissemination system for VANETs. Computer Communications. 60:53-70. https://doi.org/10.1016/j.comcom.2015.01.017 ; S ; 53 ; 70 ; 60

The final publication is available at Springer via http://dx.doi.org/10.1007/s11277-015-2392-4 ; The number of vehicles in our roads is drastically increasing, especially in developing countries. In addition, these vehicles tend to be concentrated in urban areas which present a large population. Since traffic jams have important and mostly negative consequences, such as increasing travel time, fuel consumption, and air pollution, governments are making efforts to alleviate the increasing traffic pressure, being vehicular density one of the main metrics used for assessing the road traffic conditions. However, vehicle density is highly variable in time and space, making it difficult to be estimated accurately. In this paper, we present a solution to estimate the density of vehicles in urban scenarios. Our proposal, that has been specially designed for vehicular networks, allows intelligent transportation systems to continuously estimate vehicular density by accounting for the number of beacons received per road side unit (RSU), and also considering the roadmap topology where the RSUs are located. Using V2I communications, we are able to estimate the traffic density in a certain area, which represents a key parameter to perform efficient traffic redirection, thereby reducing the vehicles' travel time and avoiding traffic. ; This work was partially supported by the Ministerio de Ciencia e Innovacion, Spain, under Grant TIN2011-27543-C03-01, and by the Government of Aragon and the European Social Fund (T91 Research Group). ; Barrachina, J.; Garrido, P.; Fogue, M.; Martínez, FJ.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2015). A V2I-based real-time traffic density estimation system in urban scenarios. Wireless Personal Communications. 83(1):259-280. https://doi.org/10.1007/s11277-015-2392-4 ; S ; 259 ; 280 ; 83 ; 1 ; Stanica, R., Chaput, E., & Beylot, A. (2011). Local density estimation for contention window adaptation in vehicular networks. In IEEE 22nd international symposium on ...

Nowadays, traffic jams in urban areas have become a problem that keeps growing every year since the number of vehicles in our cities is continuously increasing. One of the most common causes producing traffic jams are vehicle accidents. Moreover, the arrival time of the emergency services could be raised due to traffic congestion. Intelligent Transportation Systems (ITS) have a key role in order to reduce or mitigate this problem. In this paper, we propose four different approaches addressing the traffic congestion problem, comparing them to obtain the best solution. Using V2I communications, we are able to accurately estimate the traffic density in a certain area, which represents a key parameter to perform efficient traffic redirection, thereby reducing the emergency services arrival time, and avoiding traffic jams when an accident occurs. Specifically, we propose two approaches based on the Dijkstra algorithm, and two approaches based on Evolution Strategies. Notice that, when an accident occurs, time is a critical issue, and the strategies here proposed contribute to find the optimal solution within a short time period. ; This work was partially supported by the Ministerio de Ciencia e Innovacion, Spain, under Grant TIN2011-27543-C03-01, as well as by the Fundacion Universitaria Antonio Gargallo, the Obra Social de Ibercaja, under Grant 2013/B010, and by the Government of Aragon and the European Social Fund (T91 Research Group). ; Barrachina, J.; Garrido, P.; Fogue, M.; Martínez, FJ.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2014). Reducing emergence services arrival time by using vehicular communications and Evolution Strategies. Expert Systems with Applications. 41(4):1206-1217. https://doi.org/10.1016/j.eswa.2013.08.004 ; S ; 1206 ; 1217 ; 41 ; 4

©ACM 2013. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in MSWiM '13 Proceedings of the 16th ACM international conference on Modeling, analysis & simulation of wireless and mobile systems; http://dx.doi.org/10.1145/2507924.2507935. ; In Vehicular ad hoc Networks (VANETs), efficient dissemination of messages is a key factor to speed up the development of useful services and applications. In this paper, we propose a novel algorithm that automatically chooses the best dissemination scheme trying to fit the warning message delivery policy to the current characteristics of each specific vehicular scenario. Our mechanism uses as input parameters the vehicular density and the topological characteristics of the environment where the vehicles are located, in order to decide which dissemination scheme to use. Simulation results demonstrate the feasibility of our approach, which is able to support more efficient warning message dissemination in vehicular environments. ; This work was partially supported by the Ministerio de Ciencia e Innovación, Spain, under Grant TIN2011-27543-C03-01, by the Fundación Universitaria Antonio Gargallo and the Obra Social de Ibercaja, under Grant 2013/B010, as well as the Government of Aragón and the European Social Fund (T91 Research Group). ; Sanguesa, JA.; Fogue, M.; Garrido, P.; Martínez, FJ.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2013). On the Selection of Optimal Broadcast Schemes in VANETs. ACM. https://doi.org/10.1145/2507924.2507935 ; S

Communications in mobile opportunistic networks, instead of using the Internet infrastructure, take place upon the establishment of ephemeral contacts among mobile nodes using direct communication. In this paper, we analytically model the performance of mobile opportunistic networks for contact-based messaging applications in city squares or gathering points, a key challenging topic that is required for the effective design of novel services. We take into account several social aspects such as: the density of people, the dynamic of people arriving and leaving a place, the size of the messages and the duration of the contacts. We base our models on Population Processes, an approach commonly used to represent the dynamics of biological populations. We study their stable equilibrium points and obtain analytical expressions for their resolution. The evaluations performed show that these models can reproduce the dynamics of message diffusion applications. We demonstrate that when the density of people increases, the effectiveness of the diffusion is improved. Regarding the arrival and departure of people, their impact is more relevant when the density of people is low. Finally, we prove that for large message sizes the effectiveness of the epidemic diffusion is reduced, and novel diffusion protocols should be considered. © 2016 Elsevier B.V. All rights reserved. ; This work was partially supported by Ministerio de Economia y Competitividad, Spain (Grants TEC2014-52690-R & MTM2013-47093-P & SEV-2013-0323), Generalitat Valenciana, Spain (Grants AICO/2015/108 & ACOMP/2015/005) and by the Basque Government through the BERC 2014-2017 program. ; Hernández Orallo, E.; Murillo Arcila, M.; Tavares De Araujo Cesariny Calafate, CM.; Cano Escribá, JC.; Conejero Casares, JA.; Manzoni, P. (2016). Analytical evaluation of the performance of contact-based messaging applications. Computer Networks. 111:45-54. https://doi.org/10.1016/j.comnet.2016.07.006 ; S ; 45 ; 54 ; 111

© 2013 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works ; [EN] A critical issue, especially in urban areas, is the occurrence of traffic accidents, since it could generate traffic jams. Additionally, these traffic jams will negatively affect to the rescue process, increasing the emergency services arrival time, which can determine the difference between life or death for injured people involved in the accident. In this paper, we propose four different approaches addressing the traffic congestion problem, comparing them to obtain the best solution. Using V2I communications, we are able to accurately estimate the traffic density in a certain area, which represents a key parameter to perform efficient traffic redirection, thereby reducing the emergency services arrival time, and avoiding traffic jams when an accident occurs. Specifically, we propose two approaches based on the Dijkstra algorithm, and two approaches based on Evolution Strategies. Results indicate that the Density-Based Evolution Strategy system is the best one among all the proposed solutions, since it offers the lowest emergency services travel times. ; This work was partially supported by the Ministerio de Ciencia e Innovacióm , Spain, under Grant TIN2011-27543-C03-01, as well as by the Fundación Universitaria Antonio Gargallo, the Obra Social de Ibercaja, the Government of Aragon, and the European Social Fund (T91 Research Group). ; Barrachina Villalba, J.; Garrido, P.; Fogue, M.; Martínez, FJ.; Cano Escribá, JC.; Tavares De Araujo Cesariny Calafate, CM.; Manzoni, P. (2013). Using evolution strategies to reduce emergency services arrival time in case of accident. En 2013 IEEE 25th International Conference on Tools with ...

[EN] Wireless technologies are making the development of new applications and services in vehicular environments possible since they enable mobile communication between vehicles (V2V), as well as communication between vehicles and infrastructure nodes (V2I). Usually, V2V communications are dedicated to the transmission of small messages mainly focused on improving traffic safety. Instead, V2I communications allow users to access the Internet and benefit from higher level applications. The combination of both V2V and V2I, known as V2X communications, can increase the benefits even further, thereby making intelligent transportation systems (ITS) a reality. In this paper, we introduce V2X-d, a novel architecture specially designed to estimate traffic density on the road. In particular, V2X-d exploits the combination of V2V and V2I communications. Our approach is based on the information gathered by sensors (i.e., vehicles and road side units (RSUs)) and the characteristics of the roadmap topology to accurately make an estimation of the instant vehicle density. The combination of both mechanisms improves the accuracy and coverage area of the data gathered, while increasing the robustness and fault tolerance of the overall approach, e.g., using the information offered by V2V communications to provide additional density information in areas where RSUs are scarce or malfunctioning. By using our collaborative sensing scheme, future ITS solutions will be able to establish adequate dissemination protocols or to apply more efficient traffic congestion reduction policies, since they will be aware of the instantaneous density of vehicles. ; This work was supported by the Ministerio de Economia y Competitividad, Programa Estatal de Investigacion, Desarrollo e Innovacion Orientada a los Retos de la Sociedad, Proyectos I+D+I 2014, Spain, under Grant TEC2014-52690-R, and by the Government of Aragon and the European Social Fund (T91 Research Group). ; Sanguesa, JA.; Barrachina, J.; Fogue, M.; Garrido, P.; Martínez, FJ.; Cano ...