Contributions to provide a QoS-aware self-configured framework for video-streaming services over ad hoc networks

Aplicat embargament des del dia 27 d'octubre de 2021 fins 31 de juliol de 2022Ad hoc networks have attracted much attention from the research community over the last years and important technical advances have risen as a consequence. These networks are foreseen as an important kind of next generation access networks, where multimedia services will be demanded by end users from their wireless devices everywhere. In this thesis, we specially focus our research work on mobile ad hoc networks (MANETs) and on vehicular ad hoc networks (VANETs), two kind of ad hoc networks over which interesting multimedia services can be provided. The special haracteristics of MANETs/VANETs, such as mobility, dynamic network topology (specially in VANETs), energy constraints (in case of MANETs), infrastructureless and variable link capacity, make the QoS (Quality of Service) provision over these networks an important challenge for the research community. Due to that, there is a need to develop new routing protocols specially designed for MANETs and VANETs able to provide multimedia services. The main objective of this thesis is to contribute in the development of the communication framework for MANETs and VANETs to improve decisions to select paths or next hops in the moment of forwarding video-reporting messages. In this way, it would be possible to have a quick answer to manage daily problems in the city and help the emergency units (e.g., police, ambulances, health care units) in case of incidents (e.g., traffic accidents). Furthermore, in case of VANETs, a real scenario must be created and thus we have analysed the presence of obstacles in real maps. Also, in case of an obstacle found between the current forwarding node and the candidate next forwarding node, the packet is stored in a buffer, for a maximum time, until a forwarding neighbour node is found; otherwise, the packet is dropped. To improve the communication framework for MANETs, we propose a new routing protocol based on a game-theoretical scheme for N users specially designed to transmit video-reporting messages. Our proposal makes the network more efficient and provides a higher degree of satisfaction of the users by receiving much more packets with a lower average end-to-end delay, lower jitter and higher PSNR (Peak Signal-to-Noise Ratio). In addition, we propose a geographical routing protocol for VANETs that considers multiple metrics named 3MRP (Multimedia Multimetric Map-Aware Routing Protocol) [1]. 3MRP is a geographical protocol based on hop-by-hop forwarding. The metrics considered in 3MRP are the distance, the density of vehicles in transmission range, the available bandwidth, the future trajectory of the neighbouring nodes and the MAC layer losses. Those metrics are weighted to obtain a multimetric score. Thus, a node selects another node among its neighbours as the best forwarding node to increase the percentage of successful packet delivery, minimizing the average packet delay and offering a certain level of quality and service. Furthermore, a new algorithm named DSW (Dynamic Self-configured Weights) computes for each metric its corresponding weight depending on the current network conditions. As a consequence, nodes are classiffied in a better way.Les xarxes sense fils ad hoc han captat molt l'atenció per part de la comunitat científica en els últims anys, a més dels importants avenços tècnics que han sorgit. Aquestes xarxes es preveuen com un tipus important de xarxes d'accés de nova generació, a on els serveis multimèdia seran requerits pels usuaris a través dels seus dispositius sense fils desde tot arreu. En aquesta tesi, centrem el nostre treball especialment en les xarxes mòbils ad hoc (MANET, Mobile Ad hoc Network) i en les xarxes vehiculars ad hoc (VANET, Vehicular Ad hoc Network). Les característiques especials de les MANETs i les VANETs, com la mobilitat, la topologia dinàmica de la xarxa (especialment en VANETs), les restriccions de bateria (en cas de MANETs), l'absència d'infrastructura i la capacitat variable de l'enllaç sense fil fa que la provisió de la qualitat de servei en aquestes xarxes sigui un repte important per a la comunitat científica. A causa d'això, hi ha la necessitat de desenvolupar nous protocols d'encaminament especialment dissenyats per a MANETs i VANETs capaços de proporcionar els serveis de multimèdia requerits. L'objectiu principal d'aquesta tesi és proveir millores en la comunicació per a les xarxes ad hoc MANET i VANET per millorar les decisions a l'hora de seleccionar els propers camins o nodes, respectivament, en el moment de l'enviament de les trames del video. D'aquesta manera serà possible tenir una resposta ràpida per resoldre els problema diaris a la ciutat i ajudar a les unitats d'emergència (per exemple, policia, ambulàncies, unitats de salut) en cas d'incidents, com ara els accidents de trànsit. Per analitzar adequadament les nostres propostes sobre VANETs hem dissenyat un entorn de simulació realista que incorpora la presència d'edificis en mapes reals i en el cas que hi hagi un obstacle entre el node actual i el candidat per a ser el pròxim salt el paquet s'emmagatzema en un buffer, per un temps màxim, fins a trobar un nou candidat; en cas contrari, es descarta el paquet. Per millorar les comunicacions en les MANETs, proposem un nou protocol d'encaminament basat en teoria de jocs per a N usuaris especialment dissenyat per a enviar missatges de vídeo. Això fa que la xarxa sigui més eficient, i així s'aconsegueix un major grau de satisfacció dels usuaris en rebre molts més paquets amb un menor retard mig extrem a extrem, menor variació del retard (jitter ) i major PSNR (Relació Senyal Soroll de Pic) . A més, es proposa un protocol d'encaminament geogràfic basat en el reenviament hop-by-hop per a VANETs anomenat 3MRP (Multimedia Multimetric Map-Aware Routing Protocol ) [1] que prèn en consideració múltiples mètriques. Les mètriques considerades en 3MRP són la distància a destinació, la densitat de vehicles en el rang de transmissió, l'ample de banda disponible, la trajectòria futura dels nodes veíns i la perdua de paquets a la capa MAC. Aquestes mètriques es ponderen per a obtenir una puntuació multimètrica. Així, un node pot seleccionar el millor node de reenviament entre tots els seus veíns per augmentar la probabilitat d' èxit de lliurament de paquets, minimitzant el retard mitjà dels paquets i oferint un cert nivell de qualitat de servei.Las redes ad hoc han llamado mucho la atención por parte de la comunidad científica en los últimos años, además de los importantes avances técnicos que han surgido. Estas redes se prevén como un tipo importante de redes de acceso de nueva generación, donde los servicios multimedia sean requeridos por los usuarios a través de sus dispositivos inalámbricos desde todas partes. En esta tesis, centramos nuestro trabajo de investigación especialmente en las redes móviles ad hoc (MANET, Mobile Ad hoc Network) y las redes vehiculares ad hoc (VANET, Vehicular Ad hoc Network). Las características especiales de las MANETs y las VANETs, como la movilidad, la topología dinámica de la red (especialmente en VANETs), las restricciones de batería (en caso de MANETs), la ausencia de infraestructura y la capacidad variable del enlace inalámbrico hace que la provisión de la calidad de servicio en estas redes sea un reto importante para la comunidad científica. Debido a esto, existe la necesidad de desarrollar nuevos protocolos de encaminamiento especialmente diseñados para MANETs y VANETs capaces de proporcionar los servicios de multimedia requeridos. El objetivo principal de esta tesis es proveer mejoras en la comunicación para las redes ad hoc MANET y VANET para mejorar las decisiones a la hora de seleccionar los próximos caminos o nodos, respectivamente, en el momento del envío de las tramas del video y de esta manera sería posible tener una respuesta rápida para resolver los problema diarios en la ciudad y ayudar a las unidades de emergencia (por ejemplo, policía, ambulancias, unidades de salud) en caso de incidentes, como accidentes de tráfico. Para analizar adecuadamente nuestras propuestas sobre VANETs hemos diseñado un entorno de simulación realista que incorpora la presencia de edificios en mapas reales. En el caso de que haya un obstáculo entre el nodo actual y el candidato para ser el próximo salto el paquete se almacena en un buer, durante un tiempo máximo, hasta encontrar un nuevo candidato; en caso contrario, se descarta el paquete. Para mejorar las comunicaciones en las MANETs, proponemos un nuevo protocolo de encaminamiento basado en teoría de juegos para N usuarios especialmente diseñados para enviar mensajes de video. Esto hace que la red sea más eficiente, y así se consigue un mayor grado de satisfacción de los usuarios al recibir muchos más paquetes con un menor promedio de retardo de extremo a extremo, variación de retardo (jitter) y mayor PSNR (Relación Señal a Ruido de Pico). Además, se propone un protocolo de encaminamiento geográfico basado en el reenvío de salto-a-salto para VANETs llamado 3MRP (Multimedia multimetric Map-Aware Routing Protocol) [1] que incluye diversas métricas. Las métricas consideradas en 3MRP son la distancia al destino, la densidad de vehículos en el rango de transmisión, el ancho de banda disponible, la trayectoria futura de los nodos vecinos y la pérdida de paquetes en la capa MAC. Estas métricas se ponderan para obtener una puntuación multimetricanal. Así, un nodo puede seleccionar el mejor nodo de reenvío entre todos sus vecinos para aumentar la probabilidad de éxito de entrega de paquetes, minimizando el retardo medio de los paquetes y ofreciendo un cierto nivel de calidad de servicio. Por otra parte, se ha diseñado un nuevo algoritmo capaz de dar a cada métrica su correspondiente peso en función de las condiciones actuales de la red. De esta forma, los nodos se pueden clasificar de una mejor manera. Por último, se propone un nuevo protocolo de encaminamiento para VANETs llamado G-3MRP (Game Theoretical Multimedia Multimetric Map-aware Routing Protocol) [2] para enviar mensajes de video basado en teoría de juegos para N usuarios en escenarios urbanos. G-3MRP se basa en el protocolo de encaminamiento 3MRP. G-3MRP utiliza hasta tres nodos a través de los cuales los tres tipos de cuadros de video I, P y B serán enviados. Las métricas utilizadas son las mismas que en 3MRP. G-3MRP logra una mayor grado de satisfacción de los usuarios mediante la recepción de muchos más paquetes de video y con un mayor nivel de PSNR, que la anterior propuesta 3MRP+DSW. También hemos analizado el problema de detección de obstáculos en mapas reales para VANETs en escenarios urbanos. Para este propósito, hemos desarrollado nuestra herramienta REVsim [3] de tal forma que puede estar fácilmente integrada en nuestra propuesta de protocolo de encaminamiento para que las simulaciones sean más realistas.Postprint (published version

G-3MRP: a game-theoretical multimedia multimetric map-aware routing1 protocol for vehicular ad hoc networks

© 2022 Elsevier. 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 particular requirements and special features of vehicular ad hoc networks (VANETs) (e.g., special mo8 bility patterns, short link lifetimes, rapid topology changes) involve challenges for the research community. 9 One of these challenges is the development of new routing protocols specially designed for VANETs. In 10 this paper, we present a novel game-theoretical approach of a multimetric geographical routing protocol for 11 VANETs to forward video-reporting messages in smart cities. Game theory is considered a very interesting 12 theoretical framework to analyze and optimize resource allocation problems in digital communication sce13 narios. Our contribution has shown to enhance the overall performance of VANETs in urban scenarios, in 14 terms of percentage of packet losses, average end-to-end packet delay and peak signal to noise ratio (PSNR).This work was supported by the Spanish Government under research project “Enhancing Communication Protocols with Machine Learning while Protecting Sensitive Data (COMPROMISE)” PID2020-113795RB-C31, funded by MCIN/AEI/10.13039/501100011033. Ahmad M. Mezher holds a McCain Postdoctoral Fellowship in Innovation with the Electrical and Computer Engineering department at the University of New Brunswick (UNB), Canada .Peer ReviewedPostprint (author's final draft

Game-theoretical design of an adaptive distributed dissemination protocol for VANETs

Road safety applications envisaged for Vehicular Ad Hoc Networks (VANETs) depend largely on the dissemination of warning messages to deliver information to concerned vehicles. The intended applications, as well as some inherent VANET characteristics, make data dissemination an essential service and a challenging task in this kind of networks. This work lays out a decentralized stochastic solution for the data dissemination problem through two game-theoretical mechanisms. Given the non-stationarity induced by a highly dynamic topology, diverse network densities, and intermittent connectivity, a solution for the formulated game requires an adaptive procedure able to exploit the environment changes. Extensive simulations reveal that our proposal excels in terms of number of transmissions, lower end-to-end delay and reduced overhead while maintaining high delivery ratio, compared to other proposalsPeer ReviewedPostprint (published version

A probability-based multimetric routing protocol for vehicular ad hoc networks in urban scenarios

Vehicular Ad hoc Networks have received considerable attention in recent years and are considered as one of the most promising ad-hoc network technologies for intelligent transport systems. Vehicular Ad hoc Networks have special requirements and unique characteristics (e.g., special mobility patterns, short life links, rapid topology changes) which make the design of suitable routing protocols, a challenge. Consequently, an efficient routing protocol that fits with VANETs’ requirements and characteristics is a crucial task to obtain a good performance in terms of average percentage of packet losses and average end-to-end packet delay. To attain this goal, we propose a novel probabilistic multimetric routing protocol (ProMRP) that is specially designed for VANETs. ProMRP estimates the probability for each neighbor of the node currently carrying the packet, to successfully deliver a packet to destination. This probability is computed based on four designed metrics: distance to destination, node’s position, available bandwidth and nodes’ density. Furthermore, an improved version of ProMRP called EProMRP is also proposed. EProMRP includes an algorithm that accurately estimates the current position of nodes in the moment of sending the packet instead of using the last updated position obtained from the previous beacon message. Simulations are carried out in a realistic urban scenario using OMNeT++/VEINS/SUMO, including real maps from the OpenStreetMaps platform. Simulation results show a better performance of ProMRP and EProMRP compared to recent similar proposals found in the literature in terms of packet losses and end-to-end packet delay, for different vehicles’ densities.Peer ReviewedPostprint (published version

Efficient k-anonymous microaggregation of multivariate numerical data via principal component analysis

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/k-Anonymous microaggregation is a widespread technique to address the problem of protecting the privacy of the respondents involved beyond the mere suppression of their identifiers, in applications where preserving the utility of the information disclosed is critical. Unfortunately, microaggregation methods with high data utility may impose stringent computational demands when dealing with datasets containing a large number of records and attributes. This work proposes and analyzes various anonymization methods which draw upon the algebraic-statistical technique of principal component analysis (PCA), in order to effectively reduce the number of attributes processed, that is, the dimension of the multivariate microaggregation problem at hand. By preserving to a high degree the energy of the numerical dataset and carefully choosing the number of dominant components to process, we manage to achieve remarkable reductions in running time and memory usage with negligible impact in information utility. Our methods are readily applicable to high-utility SDC of large-scale datasets with numerical demographic attributes.Peer ReviewedPostprint (author's final draft

Available bandwidth-aware routing in urban vehicular ad-hoc networks

Vehicular communication for intelligent transportation systems will provide safety, comfort for passengers, and more efficient travels. This type of network has the advantage to warn drivers of any event occurred in the road ahead, such as traffic jam, accidents or bad weather. This way, the number of traffic accidents may decrease and many lives could be saved. Moreover, a better selection of non-congested roads will help to reduce pollution. Some other interesting services, such as downloading of multimedia services, would be possible and available through infrastructure along the roadside. Providing multimedia services over VANETs may require a QoS-aware routing protocol that often need to estimate available resources. In this paper, we study the performance, in realistic VANET urban scenarios, of an extension of AODV that includes the available bandwidth estimator ABE [1]. AODV-ABE establishes forwarding paths that satisfy the bandwidth required by the applications. The results, obtained on the NCTUns simulator [2], show that AODVABE could be used in urban-VANETs where vehicles’ speed is moderate.Peer ReviewedPostprint (author’s final draft

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

Mathematically optimized, recursive prepartitioning strategies for k-anonymous microaggregation of large-scale datasets

© Elsevier. 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 technical contents of this work fall within the statistical disclosure control (SDC) field, which concerns the postprocessing of the demographic portion of the statistical results of surveys containing sensitive personal information, in order to effectively safeguard the anonymity of the participating respondents. A widely known technique to solve the problem of protecting the privacy of the respondents involved beyond the mere suppression of their identifiers is the k-anonymous microaggregation. Unfortunately, most microaggregation algorithms that produce competitively low levels of distortions exhibit a superlinear running time, typically scaling with the square of the number of records in the dataset. This work proposes and analyzes an optimized prepartitioning strategy to reduce significantly the running time for the k-anonymous microaggregation algorithm operating on large datasets, with mild loss in data utility with respect to that of MDAV, the underlying method. The optimization strategy is based on prepartitioning a dataset recursively until the desired k-anonymity parameter is achieved. Traditional microaggregation algorithms have quadratic computational complexity in the form T(n2). By using the proposed method and fixing the number of recurrent prepartitions we obtain subquadratic complexity in the form T(n3/2), T(n4/3), ..., depending on the number of prepartitions. Alternatively, fixing the ratio between the size of the microcell and the macrocell on each prepartition, quasilinear complexity in the form T(nlog¿n) is achieved. Our method is readily applicable to large-scale datasets with numerical demographic attributes.Peer ReviewedPostprint (author's final draft

Optimized path selection in a game-theoretic routing protocol for video-streaming services over MANETs

Mobile ad hoc networks (MANETs) are infrastructureless networks formed by wireless mobile devices. Recently, the demand over multimedia services such as video streaming has increased specially since the number of mobile end users is growing as well. MPEG-2 VBR is one of the most fitting video coding techniques for MANETs which improves the distribution of video streams specially when it is used with a proper multipath routing scheme. In this article, we aimed to design a routing scheme to dynamically select the forwarding paths using a game-theoretic approach over a multipath routing protocol. Our proposal seeks to describe an equation of the probability p of sending video frames through the best available path. p depends on network parameters that vary throughout time. The aim is that the most important video frames (I+P) will be sent through the best path with a certain probability p and will be sent through the second best path with a probability 1-p. To achieve that, we carried out simulations done with fixed values of p and after that we applied a lineal regression method to obtain the coefficients of the equation for p. Simulations have been done to show the benefits of our proposal where interfering traffic and mobility of the nodes are present.Peer ReviewedPostprint (published version