40 research outputs found
Connectivity and Data Transmission over Wireless Mobile Systems
We live in a world where wireless connectivity is pervasive and becomes ubiquitous. Numerous devices with varying capabilities and multiple interfaces are surrounding us. Most home users use Wi-Fi routers, whereas a large portion of human inhabited land is covered by cellular networks. As the number of these devices, and the services they provide, increase, our needs in bandwidth and interoperability are also augmented. Although deploying additional infrastructure and future protocols may alleviate these problems, efficient use of the available resources is important.
We are interested in the problem of identifying the properties of a system able to operate using multiple interfaces, take advantage of user locations, identify the users that should be involved in the routing, and setup a mechanism for information dissemination. The challenges we need to overcome arise from network complexity and heterogeneousness, as well as the fact that they have no single owner or manager.
In this thesis I focus on two cases, namely that of utilizing "in-situ" WiFi Access Points to enhance the connections of mobile users, and that of establishing "Virtual Access Points" in locations where there is no fixed roadside equipment available. Both environments have attracted interest for numerous related works. In the first case the main effort is to take advantage of the available bandwidth, while in the second to provide delay tolerant connectivity, possibly in the face of disasters. Our main contribution is to utilize a database to store user locations in the system, and to provide ways to use that information to improve system effectiveness. This feature allows our system to remain effective in specific scenarios and tests, where other approaches fail
IP Mobility Support in Multi-hop Vehicular Communications Networks
The combination of infrastructure-to-vehicle and vehicle-to-vehicle communications, namely the multi-hop Vehicular Communications Network (VCN) , appears as a promising solution for the ubiquitous access to IP services in vehicular environments.
In this thesis, we address the challenges of multi-hop VCN, and investigate the seamless
provision of IP services over such network. Three different schemes are proposed and analyzed. First, we study the limitations of current standards for the provision of IP services, such as 802.11p/WAVE, and propose a framework that enables multi-hop communications and a robust IP mobility mechanism over WAVE. An accurate analytical model is developed to evaluate the throughput performance, and to determine the feasibility of the deployment of IP-based services in 802.11p/WAVE networks. Next, the IP mobility support is extended to asymmetric multi-hop VCN. The proposed IP mobility and routing mechanisms react to the asymmetric links, and also employ geographic location and road traffic information to enable predictive handovers. Moreover, since multi-hop communications suffer from security threats, it ensures that all mobility signalling is authenticated
among the participant vehicles. Last, we extend our study to a heterogeneous multi-hop
VCN, and propose a hybrid scheme that allows for the on-going IP sessions to be transferred along the heterogeneous communications system. The proposed global IP mobility scheme focuses on urban vehicular scenarios, and enables seamless communications for in-vehicle networks, commuters, and pedestrians.
The overall performance of IP applications over multi-hop VCN are improved substantially
by the proposed schemes. This is demonstrated by means of analytical evaluations, as well as extensive simulations that are carried out in realistic highway and urban vehicular scenarios. More importantly, we believe that our dissertation provides useful analytical
tools, for evaluating the throughput and delay performance of IP applications in multi-hop vehicular environments. In addition, we provide a set of practical and efficient solutions for the seamless support of IP tra c along the heterogeneous and multi-hop vehicular network, which will help on achieving ubiquitous drive-thru Internet, and infotainment traffic access in both urban and highway scenarios
Delay Tolerant Networks for Efficient Information Harvesting and Distribution in Intelligent Transportation Systems
[EN] Intelligent Transportation Systems (ITS) can make transportation safer, more efficient, and more sustainable
by applying various information and communication technologies. One of these technologies are \acfp{VN}.
\acp{VN} combine different communication solutions such as cellular networks,
\acfp{VANET}, or IEEE 802.11 technologies to provide connectivity among
vehicles, and between vehicles and road infrastructure.
This thesis focuses on VNs, and considers that the high speed of the nodes
and the presence of obstacles like buildings, produces a highly variable network
topology, as well as more frequent partitions in the network. Therefore,
classical \ac{MANET} protocols do not adapt well to VANETs. Under these
conditions, \ac{DTN}
have been proposed as an alternative able to cope with these adverse
characteristics. In DTN, when a message cannot be routed
to its destination, it is not immediately dropped but it is instead stored and
carried until a new route becomes available. The combination of VN and
DTN is called \acp{VDTN}.
In this thesis, we propose a new VDTN protocol designed to collect
information from vehicular sensors. Our proposal, called \ac{MSDP}, combines
information about the localization obtained from a GNSS system with the actual
street/road layout obtained from a Navigation System (NS) to define a new
routing metric. Both analytical and simulation results prove that MSDP outperforms
previous proposals.
Concerning the deployment of VNs and VANET technologies, technology
already left behind the innovation and the standardization phases, and it is
about time it reach the first early adopters in the market. However, most car
manufacturers have decided to implement VN devices in the form of On Board
Units (OBUs), which are expensive, heavily manufacturer dependent, and
difficult to upgrade. These facts are delaying the deployment of VN. To boost
this process, we have developed the GRCBox architecture. This architecture is
based on low-cost devices and enables the establishment of V2X, \emph{i.e.} V2I and V2V, communications
while integrating users by easing the use of general purpose devices like
smartphones, tablets or laptops. To demonstrate the viability of the GRCBox
architecture, we combined it with a DTN platform called Scampi to obtain
actual results over a real VDTN scenario. We also
present several GRCBox-aware applications that illustrate how developers can
create applications that bring the potential of VN to user devices.[ES] Los sistemas de transporte inteligente (ITS) son el soporte para el establecimiento de un
transporte más seguro, más eficiente y más sostenible mediante el uso de
tecnologías de la información y las comunicaciones.
Una de estas tecnologías son las redes vehiculares
(VNs). Las VNs combinan diferentes tecnologías de comunicación como las redes
celulares, las redes ad-hoc vehiculares (VANETs) o las redes 802.11p para
proporcionar conectividad entre vehículos, y entre vehículos y la
infraestructura de carreteras.
Esta tesis se centra en las VNs, en las cuales la alta velocidad de los
nodos
y la presencia de obstáculos como edificios producen una topología de red
altamente variable, así como frecuentes particiones en la red. Debido a estas características,
los protocolos para redes móviles ad-hoc (MANETs) no se adaptan bien a las
VANETs. En estas condiciones, las redes tolerantes a retardos (DTNs) se han
propuesto como una alternativa capaz de hacer frente a estos problemas. En DTN,
cuando un mensaje no puede ser encaminado hacia su destino, no es
inmediatamente descartado sino es almacenado hasta que una nueva ruta esta disponible.
Cuando las VNs y las DTNs se combinan surgen las redes vehiculares tolerantes
a retardos (VDTN).
En esta tesis proponemos un nuevo protocolo para VDTNs diseñado para recolectar
la información generada por sensores vehiculares. Nuestra propuesta, llamada
MSDP, combina la información obtenida del servicio de información geográfica
(GIS) con el mapa real de las calles obtenido del sistema de navegación (NS)
para definir una nueva métrica de encaminamiento. Resultados analíticos y
mediante simulaciones prueban que MSDP mejora el rendimiento de propuestas
anteriores.
En relación con el despliegue de las VNs y las tecnologías VANET, la
tecnología ha dejado atrás las fases de innovación y estandarización,
ahora es el momento de alcanzar a los primeros usuarios del mercado. Sin embargo,
la mayoría de fabricantes han decidido implementar los dispositivos para VN
como unidades de a bordo (OBU), las cuales son caras y difíciles de
actualizar. Además, las OBUs son muy dependientes del fabricante original.
Todo esto esta retrasando el despliegue de las VNs. Para acelerar la adopción
de las VNs, hemos desarrollado la arquitectura GRCBox. La arquitectura GRCBox
esta basada en un dispositivo de bajo coste que permite a los usuarios usar
comunicaciones V2X (V2V y V2I) mientras utilizan dispositivos de propósito general como
teléfonos inteligentes, tabletas o portátiles. Las pruebas incluidas en esta
tesis demuestran la viabilidad de la arquitectura GRCBox. Mediante la
combinación de nuestra GRCBox y una plataforma de DTN llamada Scampi hemos
diseñado y probado un escenario VDTN real. También presentamos como los
desarrolladores pueden crear nuevas aplicaciones GRCBox para llevar el
potencial de las VN a los dispositivos de usuario.[CA] Els sistemes de transport intel·ligent (ITS) poden crear un transport més
segur, més eficient i més sostenible mitjançant l'ús de tecnologies de la
informació i les comunicacions aplicades al transport.
Una d'aquestes tecnologies són les xarxes vehiculars (VN). Les VN combinen
diferents tecnologies de comunicació, com ara les xarxes cel·lulars, les
xarxes ad-hoc vehiculars (VANET) o les xarxes 802.11p, per a proporcionar
comunicació entre vehicles, i entre vehicles i la infraestructura de
carreteres.
Aquesta tesi se centra en les VANET, en les quals l'alta velocitat dels nodes
i la presència d'obstacles, com els edificis, produeixen una topologia de
xarxa altament variable, i també freqüents particions en la xarxa. Per aquest
motiu, els protocols per a xarxes mòbils ad-hoc (MANET) no s'adapten bé. En
aquestes condicions, les xarxes tolerants a retards (DTN) s'han proposat com
una alternativa capaç de fer front a aquests problemes. En DTN, quan un
missatge no pot ser encaminat cap a la seua destinació, no és immediatament
descartat sinó que és emmagatzemat fins que apareix una ruta nova.
Quan les VN i les DTN es combinen sorgeixen les xarxes vehicular tolerants a
retards (VDTN).
En aquesta tesi proposem un nou protocol per a VDTN dissenyat per a
recol·lectar la informació generada per sensors vehiculars. La nostra
proposta, anomenada MSDP, combina la informació obtinguda del servei
d'informació geogràfica (GIS) amb el mapa real dels carrers obtingut del
sistema de navegació (NS) per a definir una nova mètrica d'encaminament.
Resultats analítics i mitjançant simulacions proven que MSDP millora el
rendiment de propostes prèvies.
En relació amb el desplegament de les VN i les tecnologies VANET, la
tecnologia ha deixat arrere les fases d'innovació i estandardització, ara és
temps d'aconseguir als primers usuaris del mercat. No obstant això, la majoria
de fabricants han decidit implementar els dispositius per a VN com a unitats
de bord (OBU), les quals són cares i difícils d'actualitzar. A més, les OBU
són molt dependents del fabricant original. Tot això està retardant el
desplegament de les VN.
Per a accelerar l'adopció de les VN, hem desenvolupat l'arquitectura GRCBox.
L'arquitectura GRCBox està basada en un dispositiu de baix cost que permet als
usuaris usar comunicacions V2V mentre usen dispositius de propòsit general,
com ara telèfons intel·ligents, tauletes o portàtils. Les proves incloses en
aquesta tesi demostren la viabilitat de l'arquitectura GRCBox. Mitjançant la
combinació de la nostra GRCBox i la plataforma de DTN Scampi, hem dissenyat i
provat un escenari VDTN pràctic. També presentem com els desenvolupadors poden
crear noves aplicacions GRCBox per a portar el potencial de les VN als
dispositius d'usuari.Martínez Tornell, S. (2016). Delay Tolerant Networks for Efficient Information Harvesting and Distribution in Intelligent Transportation Systems [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68486TESI
Comunicações veiculares híbridas
Vehicle Communications is a promising research field, with a great potential for
the development of new applications capable of improving road safety, traffic efficiency,
as well as passenger comfort and infotainment. Vehicle communication
technologies can be short-range, such as ETSI ITS-G5 or the 5G PC5 sidelink
channel, or long-range, using the cellular network (LTE or 5G). However, none of
the technologies alone can support the expected variety of applications for a large
number of vehicles, nor all the temporal and spatial requirements of connected
and autonomous vehicles. Thus, it is proposed the collaborative or hybrid use of
short-range communications, with lower latency, and of long-range technologies,
potentially with higher latency, but integrating aggregated data of wider geographic
scope.
In this context, this work presents a hybrid vehicle communications model, capable
of providing connectivity through two Radio Access Technologies (RAT), namely,
ETSI ITS-G5 and LTE, to increase the probability of message delivery and, consequently,
achieving a more robust, efficient and secure vehicle communication
system. The implementation of short-range communication channels is done using
Raw Packet Sockets, while the cellular connection is established using the Advanced
Messaging Queuing Protocol (AMQP) protocol.
The main contribution of this dissertation focuses on the design, implementation
and evaluation of a Hybrid Routing Sublayer, capable of isolating messages that
are formed/decoded from transmission/reception processes. This layer is, therefore,
capable of managing traffic coming/destined to the application layer of intelligent
transport systems (ITS), adapting and passing ITS messages between the highest
layers of the protocol stack and the available radio access technologies.
The Hybrid Routing Sublayer also reduces the financial costs due to the use of
cellular communications and increases the efficiency of the use of the available
electromagnetic spectrum, by introducing a cellular link controller using a Beacon
Detector, which takes informed decisions related to the need to connect to a cellular
network, according to different scenarios.
The experimental results prove that hybrid vehicular communications meet the requirements
of cooperative intelligent transport systems, by taking advantage of
the benefits of both communication technologies. When evaluated independently,
the ITS-G5 technology has obvious advantages in terms of latency over the LTE
technology, while the LTE technology performs better than ITS-G5, in terms of
throughput and reliability.As Comunicações Veiculares são um campo de pesquisa promissor, com um grande
potencial de desenvolvimento de novas aplicações capazes de melhorar a segurança
nas estradas, a eficiência do tráfego, bem com o conforto e entretenimento dos
passageiros. As tecnologias de comunicação veícular podem ser de curto alcance,
como por exemplo ETSI ITS-G5 ou o canal PC5 do 5G, ou de longo alcance, recorrendo
à rede celular (LTE ou 5G). No entanto, nenhuma das tecnologias por
si só, consegue suportar a variedade expectável de aplicações para um número de
veículos elevado nem tampouco todos os requisitos temporais e espaciais dos veículos
conectados e autónomos. Assim, é proposto o uso colaborativo ou híbrido de
comunicações de curto alcance, com latências menores, e de tecnologias de longo
alcance, potencialmente com maiores latências, mas integrando dados agregados
de maior abrangência geográfica.
Neste contexto, este trabalho apresenta um modelo de comunicações veiculares
híbrido, capaz de fornecer conectividade por meio de duas Tecnologias de Acesso
por Rádio (RAT), a saber, ETSI ITS-G5 e LTE, para aumentar a probabilidade de
entrega de mensagens e, consequentemente, alcançar um sistema de comunicação
veicular mais robusto, eficiente e seguro. A implementação de canais de comunicação
de curto alcance é feita usando Raw Packet Sockets, enquanto que a ligação
celular é estabelecida usando o protocolo Advanced Messaging Queuing Protocol
(AMQP).
A contribuição principal desta dissertação foca-se no projeto, implementação e avaliação
de uma sub camada hibrída de encaminhamento, capaz de isolar mensagens
que se formam/descodificam a partir de processos de transmissão/receção. Esta
camadada é, portanto, capaz de gerir o tráfego proveniente/destinado à camada
de aplicação de sistemas inteligentes de transportes (ITS) adaptando e passando
mensagens ITS entre as camadas mais altas da pilha protocolar e as tecnologias
de acesso rádio disponíveis.
A sub camada hibrída de encaminhamento também potencia uma redução dos custos
financeiros devidos ao uso de comunicações celulares e aumenta a eficiência do
uso do espectro electromagnético disponível, ao introduzir um múdulo controlador
da ligação celular, utilizando um Beacon Detector, que toma decisões informadas
relacionadas com a necessidade de uma conexão a uma rede celular, de acordo com
diferentes cenários.
Os resultados experimentais comprovam que as comunicações veículares híbridas
cumprem os requisitos dos sistemas cooperativos de transporte inteligentes, ao
tirarem partido das vantagens de ambas tecnologias de comunicação. Quando
avaliadas de forma independente, constata-se que que a tecnologia ITS-G5 tem
vantagens evidentes em termos de latência sobre a tecnologia LTE, enquanto que
a tecnologia LTE tem melhor desempenho que a LTE, ai nível de débito e fiabilidade.Mestrado em Engenharia Eletrónica e Telecomunicaçõe
AN ADAPTIVE INFORMATION DISSEMINATION MODEL FOR VANET COMMUNICATION
Vehicular ad hoc networks (VANETs) have been envisioned to be useful in road safety and many commercial applications. The growing trend to provide communication among the vehicles on the road has provided the opportunities for developing a variety of applications for VANET. The unique characteristics of VANET bring about new research challenges
Models and Protocols for Resource Optimization in Wireless Mesh Networks
Wireless mesh networks are built on a mix of fixed and mobile nodes interconnected via wireless links to form a multihop ad hoc network. An emerging application area for wireless mesh networks is their evolution into a converged infrastructure used to share and extend, to mobile users, the wireless Internet connectivity of sparsely deployed fixed lines with heterogeneous capacity, ranging from ISP-owned broadband links to subscriber owned low-speed connections. In this thesis we address different key research issues for this networking scenario. First, we propose an analytical predictive tool, developing a queuing network model capable of predicting the network capacity and we use it in a load aware routing protocol in order to provide, to the end users, a quality of service based on the throughput. We then extend the queuing network model and introduce a multi-class queuing network model to predict analytically the average end-to-end packet delay of the traffic flows among the mobile end users and the Internet. The analytical models are validated against simulation. Second, we propose an address auto-configuration solution to extend the coverage of a wireless mesh network by interconnecting it to a mobile ad hoc network in a transparent way for the infrastructure network (i.e., the legacy Internet interconnected to the wireless mesh network). Third, we implement two real testbed prototypes of the proposed solutions as a proof-of-concept, both for the load aware routing protocol and the auto-configuration protocol. Finally we discuss the issues related to the adoption of ad hoc networking technologies to address the fragility of our communication infrastructure and to build the next generation of dependable, secure and rapidly deployable communications infrastructures
Mobile Ad-Hoc Networks
Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: vehicular ad-hoc networks, security and caching, TCP in ad-hoc networks and emerging applications. It is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks