194 research outputs found
Previous hop routing: exploiting opportunism in VANETs
Routing in highly dynamic wireless networks such as Vehicular Ad-hoc Networks
(VANETs) is a challenging task due to frequent topology changes. Sustaining
a transmission path between peers in such network environment is difficult. In
this thesis, Previous Hop Routing (PHR) is poposed; an opportunistic forwarding
protocol exploiting previous hop information and distance to destination to
make the forwarding decision on a packet-by-packet basis. It is intended for use in
highly dynamic network where the life time of a hop-by-hop path between source
and destination nodes is short. Exploiting the broadcast nature of wireless communication
avoids the need to copy packets, and enables redundant paths to be
formed. To save network resources, especially under high network loads, PHR
employs probabilistic forwarding. The forwarding probability is calculated based
on the perceived network load as measured by the arrival rate at the network
interface. We evaluate PHR in an urban VANET environment using NS2 (for
network traffic) and SUMO (for vehicular movement) simulators, with scenarios
configured to re
ect real-world conditions. The simulation scenarios are configured
to use two velocity profiles i.e. Low and high velocity. The results show that the
PHR networks able to achieve best performance as measured by Packet Delivery
Ratio (PDR) and Drop Burst Length (DBL) compared to conventional routing
protocols in high velocity scenarios
Design and implementation of simulation tools, protocols and architectures to support service platforms on vehicular networks
Tesis por compendioProducts related with Intelligent Transportation Systems (ITS) are becoming
a reality on our roads.
All car manufacturers are starting to include Internet
access in their vehicles and to integrate smartphones directly from the
dashboard, but more and more services will be introduced in the near future.
Connectivity through "vehicular networks" will become a cornerstone of every
new proposal, and offering an adequate quality of service is obviously desirable.
However, a lot of work is needed for vehicular networks to offer performances
similar to those of the wired networks.
Vehicular networks can be characterized by two main features: high variability
due to mobility levels that can reach up to 250 kilometers per hour,
and heterogeneity, being that various competing versions from different vendors
have and will be released. Therefore, to make the deployment of efficient
services possible, an extensive study must be carried out and adequate tools
must be proposed and developed. This PhD thesis addresses the service deployment
problem in these networks at three different levels: (i) the physical
and link layer, showing an exhaustive analysis of the physical channel and
models; (ii) the network layer, proposing a forwarding protocol for IP packets;
and (iii) the transport layer, where protocols are proposed to improve data
delivery.
First of all, the two main wireless technologies used in vehicular networks
where studied and modeled, namely the 802.11 family of standards, particularly
802.11p, and the cellular networks focusing on LTE. Since 802.11p is a
quite mature standard, we defined (i) a propagation and attenuation model
capable of replicating the transmission range and the fading behavior of real
802.11p devices, both in line-of-sight conditions and when obstructed by small
obstacles, and (ii) a visibility model able to deal with large obstacles, such
as buildings and houses, in a realistic manner.
Additionally, we proposed a
model based on high-level performance indicators (bandwidth and delay) for
LTE, which makes application validation and evaluation easier.
At the network layer, a hybrid protocol called AVE is proposed for packet
forwarding by switching among a set of standard routing strategies. Depending
on the specific scenario, AVE selects one out of four different routing solutions:
a) two-hop direct delivery, b) Dynamic MANET On-demand (DYMO), c)
greedy georouting, and d) store-carry-and-forward technique, to dynamically
adapt its behavior to the specific situation.
At the transport layer, we proposed a content delivery protocol for reliable
and bidirectional unicast communication in lossy links that improves content
delivery in situations where the wireless network is the bottleneck.
It has
been designed, validated, optimized, and its performance has been analyzed
in terms of throughput and resource efficiency.
Finally, at system level, we propose an edge-assisted computing model that
allows reducing the response latency of several queries by placing a computing
unit at the network edge. This way, traffic traversal through the Internet is
avoided when not needed.
This scheme could be used in both 802.11p and
cellular networks, and in this thesis we decided to focus on its evaluation using
LTE networks.
The platform presented in this thesis combines all the individual efforts to
create a single efficient platform. This new environment could be used by any
provider to improve the quality of the user experience obtainable through the
proposed vehicular network-based services.Los productos relacionados con los Sistemas Inteligentes de Transporte (ITS)
se están transformando en una realidad en nuestras carreteras. Todos los
fabricantes de coches comienzan a incluir acceso a internet en sus vehículos y a
facilitar su integración con los teléfonos móviles, pero más y más servicios se
introducirán en el futuro.
La conectividad usando las "redes vehiculares" se
convertirá en la piedra angular de cada nueva propuesta, y ofrecer una calidad
de servicio adecuada será, obviamente, deseable. Sin embargo, se necesita
una gran cantidad de trabajo para que las redes vehiculares ofrezcan un
rendimiento similar al de las redes cableadas.
Las redes vehiculares quedan definidas por sus dos características básicas:
alto dinamismo, pues los nodos pueden alcanzar una velocidad relativa de más
de 250 km/h; y heterogeneidad, por la gran cantidad de propuestas diferentes
que los fabricantes están lanzando al mercado. Por ello, para hacer posible el
despliegue de servicios sobre ellas, se impone la necesidad de hacer un estudio
en profundidad de este entorno, y deben de proponerse y desarrollarse las
herramientas adecuadas.
Esta tesis ataca la problemática del despliegue de servicios en estas redes
a tres niveles diferentes: (i) el nivel físico y de enlace, mostrando varios análisis
en profundidad del medio físico y modelos derivados para su simulación;
(ii) el nivel de red, proponiendo un protocolo de difusión de la información
para los paquetes IP; y (iii) el nivel de transporte, donde otros protocolos son
propuestos para mejorar el rendimiento del transporte de datos.
En primer lugar, se han estudiado y modelado las dos principales tecnologías
inalámbricas que se utilizan para la comunicación en redes vehiculares,
la rama de estándares 802.11, en concreto 802.11p; y la comunicación celular,
en particular LTE. Dado que el estándar 802.11p es un estándar bastante
maduro, nos centramos en crear (i) un modelo de propagación y atenuación
capaz de replicar el rango de transmisión de dispositivos 802.11p reales, en
condiciones de visión directa y obstrucción por pequeños obstáculos, y (ii) un
modelo de visibilidad capaz de simular el efecto de grandes obstáculos, como
son los edifcios, de una manera realista.
Además, proponemos un modelo
basado en indicadores de rendimiento de alto nivel (ancho de banda y retardo)
para LTE, que facilita la validación y evaluación de aplicaciones.
En el plano de red, se propone un protocolo híbrido, llamado AVE, para
el encaminamiento y reenvío de paquetes usando un conjunto de estrategias
estándar de enrutamiento. Dependiendo del escenario, AVE elige entre cuatro
estrategias diferentes: a) entrega directa a dos saltos, b) Dynamic MANET
On-demand (DYMO) c) georouting voraz, y d) una técnica store-carry-and-
forward, para adaptar su comportamiento dinámicamente a cada situación.
En el plano de transporte, se propone un protocolo bidireccional de distribución
de contenidos en canales con pérdidas que mejora la entrega de contenidos
en situaciones en las que la red es un cuello de botella, como las redes
inalámbricas.
Ha sido diseñado, validado, optimizado, y su rendimiento ha
sido analizado en términos de productividad y eficiencia en la utilización de
recursos.
Finalmente, a nivel de sistema, proponemos un modelo de computación
asistida que permite reducir la latencia en la respuesta a muchas consultas
colocando una unidad de computación en el borde de la red, i.e., la red de
acceso. Este esquema podría ser usado en redes basadas en 802.11p y en redes
celulares, si bien en esta tesis decidimos centrarnos en su evaluación usando
redes LTE.
La plataforma presentada en esta tesis combina todos los esfuerzos individuales
para crear una plataforma única y eficiente. Este nuevo entorno puede
ser usado por cualquier proveedor para mejorar la calidad de la experiencia de
usuario en los servicios desplegados sobre redes vehiculares.Els productes relacionats amb els sistemes intel · ligents de transport (ITS)
s'estan transformant en una realitat en les nostres carreteres. Tots els fabri-
cants de cotxes comencen a incloure accés a internet en els vehicles i a facilitar-
ne la integració amb els telèfons mòbils, però en el futur més i més serveis s'hi
introduiran. La connectivitat usant les xarxes vehicular esdevindrà la pedra
angular de cada nova proposta, i oferir una qualitat de servei adequada serà,
òbviament, desitjable.
No obstant això, es necessita una gran quantitat de
treball perquè les xarxes vehiculars oferisquen un rendiment similar al de les
xarxes cablejades.
Les xarxes vehiculars queden definides per dues característiques bàsiques:
alt dinamisme, ja que els nodes poden arribar a una velocitat relativa de més
de 250 km/h; i heterogeneïtat, per la gran quantitat de propostes diferents
que els fabricants estan llançant al mercat.
Per això, per a fer possible el
desplegament de serveis sobre aquestes xarxes, s'imposa la necessitat de fer un
estudi en profunditat d'aquest entorn, i cal proposar i desenvolupar les eines
adequades.
Aquesta tesi ataca la problemàtica del desplegament de serveis en aquestes
xarxes a tres nivells diferents: (i) el nivell físic i d'enllaç , mostrant diverses
anàlisis en profunditat del medi físic i models derivats per simular-lo; (ii) el
nivell de xarxa, proposant un protocol de difusió de la informació per als
paquets IP; i (iii) el nivell de transport, on es proposen altres protocols per a
millorar el rendiment del transport de dades.
En primer lloc, s'han estudiat i modelat les dues principals tecnologies
sense fils que s'utilitzen per a la comunicació en xarxes vehiculars, la branca
d'estàndards 802.11, en concret 802.11p; i la comunicació cel · lular, en partic-
ular LTE. Atès que l'estàndard 802.11p és un estàndard bastant madur, ens
centrem a crear (i) un model de propagació i atenuació capaç de replicar el
rang de transmissió de dispositius 802.11p reals, en condicions de visió directa
i obstrucció per petits obstacles, i (ii) un model de visibilitat capaç de simular
l'efecte de grans obstacles, com són els edificis, d'una manera realista. A més,
proposem un model basat en indicadors de rendiment d'alt nivell (ample de
banda i retard) per a LTE, que facilita la validació i l'avaluació d'aplicacions.
En el pla de xarxa, es proposa un protocol híbrid, anomenat AVE, per
a l'encaminament i el reenviament de paquets usant un conjunt d'estratègies
estàndard d'encaminament.
Depenent de l'escenari , AVE tria entre quatre
estratègies diferents: a) lliurament directe a dos salts, b) Dynamic MANET
On-demand (DYMO) c) georouting voraç, i d) una tècnica store-carry-and-
forward, per a adaptar-ne el comportament dinàmicament a cada situació.
En el pla de transport, es proposa un protocol bidireccional de distribució
de continguts en canals amb pèrdues que millora el lliurament de continguts
en situacions en què la xarxa és un coll de botella, com les xarxes sense fils.
Ha sigut dissenyat, validat, optimitzat, i el seu rendiment ha sigut analitzat
en termes de productivitat i eficiència en la utilització de recursos.
Finalment, a nivell de sistema, proposem un model de computació assistida
que permet reduir la latència en la resposta a moltes consultes col · locant una
unitat de computació a la vora de la xarxa, és a dir, la xarxa d'accés. Aquest
esquema podria ser usat en xarxes basades en 802.11p i en xarxes cel · lulars, si
bé en aquesta tesi decidim centrar-nos en la seua avaluació usant xarxes LTE.
La plataforma presentada en aquesta tesi combina tots els esforços indi-
viduals per a crear una plataforma única i eficient. Aquest nou entorn pot ser
usat per qualsevol proveïdor per a millorar la qualitat de l'experiència d'usuari
en els serveis desplegats sobre xarxes vehiculars.Báguena Albaladejo, M. (2017). Design and implementation of simulation tools, protocols and architectures to support service platforms on vehicular networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/85333TESISCompendi
Evaluation of unidirectional background push content download services for the delivery of television programs
Este trabajo de tesis presenta los servicios de descarga de contenido en modo push como un
mecanismo eficiente para el envío de contenido de televisión pre-producido sobre redes de
difusión. Hoy en día, los operadores de red dedican una cantidad considerable de recursos
de red a la entrega en vivo de contenido televisivo, tanto sobre redes de difusión como
sobre conexiones unidireccionales. Esta oferta de servicios responde únicamente a
requisitos comerciales: disponer de los contenidos televisivos en cualquier momento y
lugar. Sin embargo, desde un punto de vista estrictamente académico, el envío en vivo es
únicamente un requerimiento para el contenido en vivo, no para contenidos que ya han sido
producidos con anterioridad a su emisión. Más aún, la difusión es solo eficiente cuando el
contenido es suficientemente popular.
Los servicios bajo estudio en esta tesis utilizan capacidad residual en redes de difusión para
enviar contenido pre-producido para que se almacene en los equipos de usuario. La
propuesta se justifica únicamente por su eficiencia. Por un lado, genera valor de recursos de
red que no se aprovecharían de otra manera. Por otro lado, realiza la entrega de contenidos
pre-producidos y populares de la manera más eficiente: sobre servicios de descarga de
contenidos en difusión.
Los resultados incluyen modelos para la popularidad y la duración de contenidos, valiosos
para cualquier trabajo de investigación basados en la entrega de contenidos televisivos.
Además, la tesis evalúa la capacidad residual disponible en redes de difusión, por medio de
estudios empíricos. Después, estos resultados son utilizados en simulaciones que evalúan
las prestaciones de los servicios propuestos en escenarios diferentes y para aplicaciones
diferentes. La evaluación demuestra que este tipo de servicios son un recurso muy útil para
la entrega de contenido televisivo.This thesis dissertation presents background push Content Download Services as an
efficient mechanism to deliver pre-produced television content through existing broadcast
networks. Nowadays, network operators dedicate a considerable amount of network
resources to live streaming live, through both broadcast and unicast connections. This
service offering responds solely to commercial requirements: Content must be available
anytime and anywhere. However, from a strictly academic point of view, live streaming is
only a requirement for live content and not for pre-produced content. Moreover,
broadcasting is only efficient when the content is sufficiently popular.
The services under study in this thesis use residual capacity in broadcast networks to push
popular, pre-produced content to storage capacity in customer premises equipment. The
proposal responds only to efficiency requirements. On one hand, it creates value from
network resources otherwise unused. On the other hand, it delivers popular pre-produced
content in the most efficient way: through broadcast download services.
The results include models for the popularity and the duration of television content,
valuable for any research work dealing with file-based delivery of television content. Later,
the thesis evaluates the residual capacity available in broadcast networks through empirical
studies. These results are used in simulations to evaluate the performance of background
push content download services in different scenarios and for different applications. The
evaluation proves that this kind of services can become a great asset for the delivery of
television contentFraile Gil, F. (2013). Evaluation of unidirectional background push content download services for the delivery of television programs [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31656TESI
Leveraging Resources on Anonymous Mobile Edge Nodes
Smart devices have become an essential component in the life of mankind. The quick rise of smartphones, IoTs, and wearable devices enabled applications that were not possible few years ago, e.g., health monitoring and online banking. Meanwhile, smart sensing laid the infrastructure for smart homes and smart cities. The intrusive nature of smart devices granted access to huge amounts of raw data. Researchers seized the moment with complex algorithms and data models to process the data over the cloud and extract as much information as possible. However, the pace and amount of data generation, in addition to, networking protocols transmitting data to cloud servers failed short in touching more than 20% of what was generated on the edge of the network. On the other hand, smart devices carry a large set of resources, e.g., CPU, memory, and camera, that sit idle most of the time. Studies showed that for plenty of the time resources are either idle, e.g., sleeping and eating, or underutilized, e.g. inertial sensors during phone calls. These findings articulate a problem in processing large data sets, while having idle resources in the close proximity. In this dissertation, we propose harvesting underutilized edge resources then use them in processing the huge data generated, and currently wasted, through applications running at the edge of the network.
We propose flipping the concept of cloud computing, instead of sending massive amounts of data for processing over the cloud, we distribute lightweight applications to process data on users\u27 smart devices. We envision this approach to enhance the network\u27s bandwidth, grant access to larger datasets, provide low latency responses, and more importantly involve up-to-date user\u27s contextual information in processing. However, such benefits come with a set of challenges: How to locate suitable resources? How to match resources with data providers? How to inform resources what to do? and When? How to orchestrate applications\u27 execution on multiple devices? and How to communicate between devices on the edge?
Communication between devices at the edge has different parameters in terms of device mobility, topology, and data rate. Standard protocols, e.g., Wi-Fi or Bluetooth, were not designed for edge computing, hence, does not offer a perfect match. Edge computing requires a lightweight protocol that provides quick device discovery, decent data rate, and multicasting to devices in the proximity. Bluetooth features wide acceptance within the IoT community, however, the low data rate and unicast communication limits its use on the edge. Despite being the most suitable communication protocol for edge computing and unlike other protocols, Bluetooth has a closed source code that blocks lower layer in front of all forms of research study, enhancement, and customization. Hence, we offer an open source version of Bluetooth and then customize it for edge computing applications.
In this dissertation, we propose Leveraging Resources on Anonymous Mobile Edge Nodes (LAMEN), a three-tier framework where edge devices are clustered by proximities. On having an application to execute, LAMEN clusters discover and allocate resources, share application\u27s executable with resources, and estimate incentives for each participating resource. In a cluster, a single head node, i.e., mediator, is responsible for resource discovery and allocation. Mediators orchestrate cluster resources and present them as a virtually large homogeneous resource. For example, two devices each offering either a camera or a speaker are presented outside the cluster as a single device with both camera and speaker, this can be extended to any combination of resources. Then, mediator handles applications\u27 distribution within a cluster as needed. Also, we provide a communication protocol that is customizable to the edge environment and application\u27s need. Pushing lightweight applications that end devices can execute over their locally generated data have the following benefits: First, avoid sharing user data with cloud server, which is a privacy concern for many of them; Second, introduce mediators as a local cloud controller closer to the edge; Third, hide the user\u27s identity behind mediators; and Finally, enhance bandwidth utilization by keeping raw data at the edge and transmitting processed information. Our evaluation shows an optimized resource lookup and application assignment schemes. In addition to, scalability in handling networks with large number of devices. In order to overcome the communication challenges, we provide an open source communication protocol that we customize for edge computing applications, however, it can be used beyond the scope of LAMEN. Finally, we present three applications to show how LAMEN enables various application domains on the edge of the network.
In summary, we propose a framework to orchestrate underutilized resources at the edge of the network towards processing data that are generated in their proximity. Using the approaches explained later in the dissertation, we show how LAMEN enhances the performance of applications and enables a new set of applications that were not feasible
Mobile Ad Hoc Networks
Guiding readers through the basics of these rapidly emerging networks to more advanced concepts and future expectations, Mobile Ad hoc Networks: Current Status and Future Trends identifies and examines the most pressing research issues in Mobile Ad hoc Networks (MANETs). Containing the contributions of leading researchers, industry professionals, and academics, this forward-looking reference provides an authoritative perspective of the state of the art in MANETs. The book includes surveys of recent publications that investigate key areas of interest such as limited resources and the mobility of mobile nodes. It considers routing, multicast, energy, security, channel assignment, and ensuring quality of service. Also suitable as a text for graduate students, the book is organized into three sections: Fundamentals of MANET Modeling and Simulation—Describes how MANETs operate and perform through simulations and models Communication Protocols of MANETs—Presents cutting-edge research on key issues, including MAC layer issues and routing in high mobility Future Networks Inspired By MANETs—Tackles open research issues and emerging trends Illustrating the role MANETs are likely to play in future networks, this book supplies the foundation and insight you will need to make your own contributions to the field. It includes coverage of routing protocols, modeling and simulations tools, intelligent optimization techniques to multicriteria routing, security issues in FHAMIPv6, connecting moving smart objects to the Internet, underwater sensor networks, wireless mesh network architecture and protocols, adaptive routing provision using Bayesian inference, and adaptive flow control in transport layer using genetic algorithms
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