Contribution to the design of VANET routing protocols for realistic urban environments

One of the main concerns of the cities' administration is mobility management. In Intelligent Transportation Systems (ITS), pedestrians, vehicles and public transportation systems could share information and react to any situation in the city. The information sensed by vehicles could be useful for other vehicles and for the mobility authorities. Vehicular Ad hoc Networks (VANETs) make possible the communication between vehicles (V2I) and also between vehicles and fixed infrastructure (V2I) managed by the city's authorities. In addition, VANET routing protocols minimize the use of fixed infrastructure since they employ multi-hop V2V communication to reach reporting access points of the city. This thesis aims to contribute in the design of VANET routing protocols to enable reporting services (e.g., vehicular traffic notifications) in urban environments. The first step to achieve this global objective has been the study of components and tools to mimic a realistic VANET scenario. Moreover, we have analyzed the impact of the realism of each one of those components in the simulation results. Then, we have improved the Address Resolution procedure in VANETs by including it in the routing signaling messages. Our approach simplifies the VANET operation and increases the packet delivery ratio as consequence. Afterwards, we have tackled the issue of having duplicate packets in unicast communications and we have proposed routing filters to lower their presence. This way we have been able to increase the available bandwidth and reduce the average packet delay with a slight increase of the packet losses. Besides, we have proposed a Multi-Metric Map aware routing protocol (MMMR) that incorporates four routing metrics (distance, trajectory, vehicle density and available bandwidth) to take the forwarding decisions. With the aim of increasing the number of delivered packets in MMMR, we have developed a Geographical Heuristic Routing (GHR) algorithm. GHR integrates Tabu and Simulated Annealing heuristic optimization techniques to adapt its behavior to the specific scenario characteristics. GHR is generic because it could use any geographical routing protocol to take the forwarding decisions. Additionally, we have designed an easy to implement forwarding strategy based on an extended topology information area of two hops, called 2-hops Geographical Anycast Routing (2hGAR) protocol. Results show that controlled randomness introduced by GHR improves the default operation of MMMR. On the other hand, 2hGAR presents lower delays than GHR and higher packet delivery ratio, especially in high density scenarios. Finally, we have proposed two mixed (integer and linear) optimization models to detect the best positions in the city to locate the Road Side Units (RSUs) which are in charge of gathering all the reporting information generated by vehicles.Una de las principales preocupaciones en la administración de las ciudades es la gestión de la movilidad de sus vehículos, debido a los problemas de tráfico como atascos y accidentes. En los sistemas inteligentes de transporte (SIT), peatones, vehículos y transporte público podrán compartir información y adaptarse a cualquier situación que suceda en la ciudad. La información obtenida por los sensores de los vehículos puede ser útil para otros vehículos y para las autoridades de movilidad. Las redes ad hoc vehiculares (VANETs) hacen posible la comunicación entre los propios vehículos (V2V) y entre vehículos y la infraestructura fija de la red de la ciudad (V2I). Asimismo, los protocolos de encaminamiento para redes vehiculares minimizan el uso de infraestructura fija de red, ya que los protocolos de encaminamiento VANET emplean comunicaciones multisalto entre vehículos para encaminar los mensajes hasta los puntos de acceso de la red en la ciudad. El objetivo de esta tesis doctoral es contribuir en el diseño de protocolos de encaminamiento en redes ad hoc vehiculares para servicios de notificaciones (p.ej. reportes del estado del tráfico) en entornos urbanos. El primer paso para alcanzar este objetivo general ha sido el estudio de componentes y herramientas para simular un escenario realista de red ad hoc vehicular. Además, se ha analizado el impacto del nivel de realismo de cada uno de los componentes de simulación en los resultados obtenidos. Así también, se ha propuesto un mecanismo de resolución de direcciones automático y coherente para redes VANET a través del uso de los propios mensajes de señalización de los protocolos de encaminamiento. Esta mejora simplifica la operación de una red ad hoc vehicular y como consecuencia aumenta la tasa de recepción de paquetes. A continuación, se ha abordado el problema de la aparición inesperada de paquetes de datos duplicados en una comunicación punto a punto. Para ello, se ha propuesto el filtrado de paquetes duplicados a nivel del protocolo de encaminamiento. Esto ha producido un incremento del ancho disponible en el canal y una reducción del retardo medio en la trasmisión de un paquete, a costa de un mínimo aumento de la pérdida de paquetes. Por otra parte, hemos propuesto un protocolo de encaminamiento multi-métrica MMMR (Multi-Metric Map-aware Routing protocol), el cual incorpora cuatro métricas (distancia al destino, trayectoria, densidad de vehículos y ancho de banda) en las decisiones de encaminamiento. Con el objetivo de aumentar la tasa de entrega de paquetes en MMMR, hemos desarrollado un algoritmo heurístico de encaminamiento geográfico denominado GHR (Geographical Heuristic Routing). Esta propuesta integra las técnicas de optimización Tabu y Simulated Annealing, que permiten a GHR adaptarse a las características específicas del escenario. Adicionalmente, hemos propuesto 2hGAR (2-hops Geographical Anycast Routing), un protocolo de encaminamiento anycast que emplea información de la topología de red a dos saltos de distancia para tomar la decisión de encaminamiento de los mensajes. Los resultados muestran que la aleatoriedad controlada de GHR en su operación mejora el rendimiento de MMMR. Asimismo, 2hGAR presenta retardos de paquete menores a los obtenidos por GHR y una mayor tasa de paquetes entregados, especialmente en escenarios con alta densidad de vehículos. Finalmente, se han propuesto dos modelos de optimización mixtos (enteros y lineales) para detectar los mejores lugares de la ciudad donde ubicar los puntos de acceso de la red, los cuales se encargan de recolectar los reportes generados por los vehículos.Postprint (published version

Video-on-demand optimization using an interior-point algorithm

A Content Delivery Network (CDN) aims to provide efficient movement of massive digital content (multimedia and files) across the Internet. This is achieved by putting the content in servers closer to the costumer. Video-On-Demand service is an application of CDN where videos have to be located strategically to avoid network congestion and servers saturation. Therefore, the problem of optimal placement of videos arises. This problem has a block diagonal structure with linking constraints on links and servers capacities. In this project, we solve huge instances of a video placement problem over three real network topologies with a specialized interior point solver named BlockIP. The evaluated instances range from 7 to 300 millions of variables and the difficulty of the instances depends on the size of servers, links bandwidth and network topology. Our results: 1) verified characteristics of BlockIP like regularization and the intensive computation in the last iterations and 2) showed that BlockIP found optimal solution in all the evaluated instances with a good optimality gap. On the contrary, state-of-art CPLEX cannot reach an optimal, feasible solution in some difficult instances and needs almost twice the memory of BlockIP. However, CPLEX solved most of feasible instances at least twice faster than BlockI

Design of a simple monitoring system for large-scale networks

Actualmente, existen muchas herramientas de administración de redes que tratan de monitorizar dispositivos de diferentes casas fabricantes. Sin embargo, ninguna de ellas permite automatizar las tareas de monitoreo que se realizan en la red. Para solventar este problema, se propone un sistema a medida que verifica automáticamente los archivos de configuración de los equipos de red para que los técnicos puedan dedicar su tiempo a solucionar los fallos encontrados, lo que dará como resultado un uso más eficiente de sus días de trabajo. El sistema de monitoreo propuesto se desarrolla para la red WAN de la Corporación Nacional de Telecomunicaciones (CNT EP) de Ecuador, en el cual se utiliza dos formas para el análisis automático de los registros de configuración: 1) mediante el uso interactivo de comandos que se pueden usar en cualquiera de los dispositivos, independientemente de su marca. 2) mediante el uso de los objetos MIB de Cisco, que son la mayoría de los dispositivos de la red. El sistema se desarrolló utilizando software gratuito y nuestro sistema lleva a cabo la supervisión automática de la red en 14 horas, lo que representa una reducción en el tiempo de aproximadamente el 94%.Currently, there are network management tools that try to monitor devices from different manufacturers. However, none of them allow you to automate the monitoring tasks carried out on the network. To tackle this problem, we propose a tailored system that automatically checks the networking devices’ configuration files. In this way, the technicians can spend their time resolving the faults found, resulting in a more efficient use of their workdays. The proposed monitoring system was developed for the WAN of Corporación Nacional de Telecomunicaciones (CNT EP) of Ecuador, in which two forms are used for the automatic analysis of configuration records: 1) by interactive use of commands that can be used in any of the devices, independently of his brand. 2) by using the MIB objects of Cisco, which are most of the network devices. The system was developed using free software and the whole, automatic network monitoring is carried out by our system in 14 hours, which represents a reduction in time of approximately 94%

A traffic-aware electric vehicle charging management system for smart cities

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/The expected increase in the number of electric vehicles (EVs) in the coming years will contribute to reducing CO2 pollution in our cities. Currently, EVs' users may suffer from distress due to long charging service times and overloaded charging stations (CSs). Critical traffic conditions (e.g., traffic jams) affect EVs' trip time (TT) towards CSs and thus influence the total trip duration. With this concern, Intelligent transport systems (ITS) and more specifically connected vehicle technologies, can leverage an efficient real-time EV charging service by jointly considering CSs status and traffic conditions in the city. In this work, we propose a scheme to manage EVs' charging planning, focusing on the selection of a CS for the energy-requiring EV. The proposed scheme considers anticipated charging slots reservations performed through a vehicular ad hoc network (VANET), which has been regarded as a cost-efficient communication framework. In specific, we consider two aspects: 1) the EV's total trip time towards its destination considering an intermediate charging at each candidate CS, and 2) the communication delay of the VANET routing protocol. First, in order to estimate the EV's total trip time, our CS selection scheme takes into account the average road speed, traffic lights, and route distance, along the path of the EV. The optimal CS that produces the minimum total charging service time (including the TT) is suggested to that energy-requiring EV. Then, we introduce two communication modes based on geographical routing protocols for VANETs to attain an anticipated charging slot reservation. Simulation results show that with our charging scheme EVs' charging service time is reduced and more EVs are successfully charged.Peer ReviewedPostprint (author's final draft

Deployment of OMNET++

Nowadays, network simulators are frequently used to study services, applications and to solve problems in complex scenarios of communications. For this reason, the objective of this article is to introduce detailed information about installation of OMNET++ to new users. In this report, we show how to install OMNET++ simulator over a widely used distribution of Linux and how to integrate "Inet", "Inetmanet" and "Veins" frameworks with the simulator. We take care to explain this integration step-by-step. This tutorial includes: a virtual machine as additional material. Our objective is make it easy for a beginner research community in OMNET++ and to maintain an open environment of knowledge.Preprin

Coherent, automatic address resolution for vehicular ad hoc networks

Published in: Int. J. of Ad Hoc and Ubiquitous Computing, 2017 Vol.25, No.3, pp.163 - 179. DOI: 10.1504/IJAHUC.2017.10001935The interest in vehicular communications has increased notably. In this paper, the use of the address resolution (AR) procedures is studied for vehicular ad hoc networks (VANETs). We analyse the poor performance of AR transactions in such networks and we present a new proposal called coherent, automatic address resolution (CAAR). Our approach inhibits the use of AR transactions and instead increases the usefulness of routing signalling to automatically match the IP and MAC addresses. Through extensive simulations in realistic VANET scenarios using the Estinet simulator, we compare our proposal CAAR to classical AR and to another of our proposals that enhances AR for mobile wireless networks, called AR+. In addition, we present a performance evaluation of the behaviour of CAAR, AR and AR+ with unicast traffic of a reporting service for VANETs. Results show that CAAR outperforms the other two solutions in terms of packet losses and furthermore, it does not introduce additional overhead.Postprint (published version

Large-scale simulations manager tool for OMNeT ++: expediting simulations and post-processing analysis

Usually, simulations are the first approach to evaluate wireless and mobile networks due to the difficulties involved in deploying real test scenarios. Working with simulations, testing, and validating the target network model often requires a large number of simulation runs. Consequently, there are a significant amount of outcomes to be analyzed to finally plot results. One of the most extensively used simulators for wireless and mobile networks is OMNeT++. This simulation environment provides useful tools to automate the execution of simulation campaigns, yet single-scenario simulations are also supported where the assignation of resources (i.e., CPUs) has to be declared manually. However, conducting a large number of simulations is still cumbersome and can be improved to make it easier, faster, and more comfortable to analyze. In this work, we propose a large-scale simulations framework called simulations manager for OMNeT ++ (SMO). SMO allows OMNeT++ users to quickly and easily execute large-scale network simulations, hiding the tedious process of conducting big simulation campaigns. Our framework automates simulations executions, resources assignment, and post-simulation data analysis through the use of Python’s wide established statistical analysis tools. Besides, our tool is flexible and easy to adapt to many different network scenarios. Our framework is accompanied by a command-line environment allowing a fast and easy manipulation that allows users to significantly reduce the total processing time to carry out large sets of simulations about 25% of the original time. Our code and its documentation are publicly available at GitHub and on our website.This work was supported by the Spanish Government through the Research Project sMArt Grid Using Open Source Intelligence (MAGOS) under Grant TEC2017-84197-C4-3-R. The work of Pablo Andrés Barbecho Bautista was supported by a grant from the Secretaría Nacional de Educación Superior, Ciencia y Tecnología (SENESCYT). The work of Leticia Lemus CÁrdenas was supported by a Ph.D. grant from the Academic Coordination of the University of Guadalajara, Mexico.Peer ReviewedPostprint (published version

Digital hyper-transparency: leading e-government against privacy

© 2018 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.For a long time, the Internet and web technologies have supported a more fluid interaction between public institutions and citizens through e-government. With this spirit, several public services are being offered online. One of such services, though not a standard one, is transparency. Strongly encouraged by open-data initiatives, transparency is being marketed as a powerful mechanism to fight corruption. Leveraging communication technologies, societies are broadly adopting online transparency practices to give the general public more control over the scrutiny of state institutions. However, a neglected implementation of transparency may cause almost unlimited access to large amounts of information, a side effect we call hyper-transparency. Inevitably, serious privacy risks arise for the individuals in this context. In this work, we analyze the emergence of hyper-transparent practices in Ecuador, a country recently involved in a fierce attempt to offer free access to public information as a fundamental right enabled through e-government. Moreover, we systematically dissect the large amount of microdata released online by Ecuadorian public institutions. Accordingly, we also unveil here a scenario where sensitive information of public employees is openly released under transparency laws. After exposing potential privacy violations, we elaborate on some mechanisms aimed at protecting citizens from such violationsPeer ReviewedPostprint (author's final draft