36 research outputs found
Hybrid routing scheme for vehicular delay tolerant networks
In Vehicular Delay Tolerant Networks (VDTN) connection from source to destination at any required period is not necessarily available. Therefore, the node with the message, save it in its own buffer and carry it until an opportunity comes across for forwarding. Fix nodes enhances the performance of VDTN. It helps in message storage and relaying messages. Due to mobility the bit error rate is high in mobile nodes connection but it is not considered in any of the previous routing schemes for VDTN. The connection between fix nodes will always have low bit error rate as compared to connection involving mobile nodes. All the pervious schemes are one dimensional. Environmental hindrances are not taken under consideration as well. Its effect can be both negative and positive. In this paper, a scheme titled Hybrid routing scheme is suggested to overcome the above stated problems. Features of another vehicular network called Vehicular Ad Hoc Networks (VANETs) are added to Maximum Priority (MaxProp) routing scheme for VDTN. Different propagation models of VANETs are implemented for both with and without mobile node communication for VDTN. The concept of bit error rate is also featured in Hybrid routing scheme. This makes Hybrid routing scheme two dimensional and more intelligent. The implementation and performance assessment of the proposed scheme is evaluated via Opportunistic Network Environment (ONE) Simulator. The Hybrid routing scheme outperform MaxProp in terms of the delivery probability and delivery delay
Connectivity Analysis in Vehicular Ad-hoc Network based on VDTN
In the last decade, user demand has been increasing exponentially based on modern communication systems. One of these new technologies is known as mobile ad-hoc networking (MANET). One part of MANET is called a vehicular ad-hoc network (VANET). It has different types such as vehicle-to-vehicle (V2V), vehicular delay-tolerant networks, and vehicle-to-infrastructure (V2I). To provide sufficient quality of communication service in the Vehicular Delay-Tolerant Network (VDTN), it is important to present a comprehensive survey that shows the challenges and limitations of VANET. In this paper, we focus on one type of VANET, which is known as VDTNs. To investigate realistic communication systems based on VANET, we considered intelligent transportation systems (ITSs) and the possibility of replacing the roadside unit with VDTN. Many factors can affect the message propagation delay. When road-side units (RSUs) are present, which leads to an increase in the message delivery efficiency since RSUs can collaborate with vehicles on the road to increase the throughput of the network, we propose new methods based on environment and vehicle traffic and present a comprehensive evaluation of the newly suggested VDTN routing method. Furthermore, challenges and prospects are presented to stimulate interest in the scientific community
Traffic differentiation support in vehicular delay-tolerant networks
Vehicular Delay-Tolerant Networking (VDTN) is a Delay-Tolerant Network (DTN) based architecture concept for transit networks, where vehicles movement and their bundle relaying service is opportunistically exploited to enable non-real time applications, under environments prone to connectivity disruptions, network partitions and potentially long delays. In VDTNs, network resources may be limited, for instance due to physical constraints of the network nodes. In order to be able to prioritize applications traffic according to its requirements in such constrained scenarios, traffic differentiation mechanisms must be introduced at the VDTN architecture. This work considers a priority classes of service (CoS) model and investigates how different buffer management strategies can be combined with drop and scheduling policies, to provide strict priority based services, or to provide custom allocation of network resources. The efficiency and tradeoffs of these proposals is evaluated through extensive simulation.Part of this work has been supported by Instituto de Telecomunicações, Next Generation Networks and Applications Group (NetGNA), Portugal, in the framework of the Project VDTN@Lab, and by the Euro-NF Network of Excellence of the Seventh Framework Programme of EU
Performance of management solutions and cooperation approaches for vehicular delay-tolerant networks
A wide range of daily-life applications supported by vehicular networks attracted the interest,
not only from the research community, but also from governments and the automotive
industry. For example, they can be used to enable services that assist drivers on the roads (e.g.,
road safety, traffic monitoring), to spread commercial and entertainment contents (e.g., publicity),
or to enable communications on remote or rural regions where it is not possible to have
a common network infrastructure. Nonetheless, the unique properties of vehicular networks
raise several challenges that greatly impact the deployment of these networks.
Most of the challenges faced by vehicular networks arise from the highly dynamic network
topology, which leads to short and sporadic contact opportunities, disruption, variable
node density, and intermittent connectivity. This situation makes data dissemination an interesting
research topic within the vehicular networking area, which is addressed by this study.
The work described along this thesis is motivated by the need to propose new solutions to deal
with data dissemination problems in vehicular networking focusing on vehicular delay-tolerant
networks (VDTNs).
To guarantee the success of data dissemination in vehicular networks scenarios it is important
to ensure that network nodes cooperate with each other. However, it is not possible
to ensure a fully cooperative scenario. This situation makes vehicular networks suitable to the
presence of selfish and misbehavior nodes, which may result in a significant decrease of the
overall network performance. Thus, cooperative nodes may suffer from the overwhelming load
of services from other nodes, which comprises their performance.
Trying to solve some of these problems, this thesis presents several proposals and studies
on the impact of cooperation, monitoring, and management strategies on the network performance
of the VDTN architecture. The main goal of these proposals is to enhance the network
performance. In particular, cooperation and management approaches are exploited to improve
and optimize the use of network resources. It is demonstrated the performance gains attainable
in a VDTN through both types of approaches, not only in terms of bundle delivery probability,
but also in terms of wasted resources.
The results and achievements observed on this research work are intended to contribute
to the advance of the state-of-the-art on methods and strategies for overcome the challenges
that arise from the unique characteristics and conceptual design of vehicular networks.O vasto número de aplicações e cenários suportados pelas redes veiculares faz com que
estas atraiam o interesse não só da comunidade científica, mas também dos governos e da indústria
automóvel. A título de exemplo, estas podem ser usadas para a implementação de serviços
e aplicações que podem ajudar os condutores dos veículos a tomar decisões nas estradas, para
a disseminação de conteúdos publicitários, ou ainda, para permitir que existam comunicações
em zonas rurais ou remotas onde não é possível ter uma infraestrutura de rede convencional.
Contudo, as propriedades únicas das redes veiculares fazem com que seja necessário ultrapassar
um conjunto de desafios que têm grande impacto na sua aplicabilidade.
A maioria dos desafios que as redes veiculares enfrentam advêm da grande mobilidade dos
veículos e da topologia de rede que está em constante mutação. Esta situação faz com que este
tipo de rede seja suscetível de disrupção, que as oportunidades de contacto sejam escassas e de
curta duração, e que a ligação seja intermitente. Fruto destas adversidades, a disseminação dos
dados torna-se um tópico de investigação bastante promissor na área das redes veiculares e por
esta mesma razão é abordada neste trabalho de investigação. O trabalho descrito nesta tese é
motivado pela necessidade de propor novas abordagens para lidar com os problemas inerentes
à disseminação dos dados em ambientes veiculares.
Para garantir o sucesso da disseminação dos dados em ambientes veiculares é importante
que este tipo de redes garanta a cooperação entre os nós da rede. Contudo, neste tipo de ambientes
não é possível garantir um cenário totalmente cooperativo. Este cenário faz com que
as redes veiculares sejam suscetíveis à presença de nós não cooperativos que comprometem
seriamente o desempenho global da rede. Por outro lado, os nós cooperativos podem ver o seu
desempenho comprometido por causa da sobrecarga de serviços que poderão suportar.
Para tentar resolver alguns destes problemas, esta tese apresenta várias propostas e estudos
sobre o impacto de estratégias de cooperação, monitorização e gestão de rede no desempenho
das redes veiculares com ligações intermitentes (Vehicular Delay-Tolerant Networks
- VDTNs). O objetivo das propostas apresentadas nesta tese é melhorar o desempenho global
da rede. Em particular, as estratégias de cooperação e gestão de rede são exploradas para
melhorar e optimizar o uso dos recursos da rede. Ficou demonstrado que o uso deste tipo de
estratégias e metodologias contribui para um aumento significativo do desempenho da rede,
não só em termos de agregados de pacotes (“bundles”) entregues, mas também na diminuição
do volume de recursos desperdiçados.
Os resultados observados neste trabalho procuram contribuir para o avanço do estado
da arte em métodos e estratégias que visam ultrapassar alguns dos desafios que advêm das
propriedades e desenho conceptual das redes veiculares
Recommended from our members
ePRIVO: an enhanced PRIvacy-preserVing opportunistic routing protocol for vehicular delay-tolerant networks
This article proposes an enhanced PRIvacy preserVing Opportunistic routing protocol (ePRIVO) for Vehicular Delay-Tolerant Networks (VDTN). ePRIVO models a VDTN as a time-varying neighboring graph where edges correspond to neighboring relationship between pairs of vehicles. It addresses the problem of vehicles taking routing decision meanwhile keeping their information private, i.e, vehicles compute their similarity and/or compare their routing metrics in a private manner using the Paillier homomorphic encryption scheme.
The effectiveness of ePRIVO is supported through extensive simulations with synthetic mobility models and a real mobility trace. Simulation results show that ePRIVO presents on average very low cryptographic costs in most scenarios. Additionally, ePRIVO presents on average gains of approximately 29% and 238% in terms of delivery ratio for the real and synthetic scenarios considered compared to other privacy-preserving routing protocols
Performance Assessment of Aggregation and Deaggregation Algorithms in Vehicular Delay-Tolerant Networks
Vehicular Delay-Tolerant Networks (VDTNs) are a new approach for vehicular
communications where vehicles cooperate with each other, acting as the
communication infrastructure, to provide low-cost asynchronous opportunistic
communications. These communication technologies assume variable delays
and bandwidth constraints characterized by a non-transmission control protocol/
internet protocol architecture but interacting with it at the edge of the
network.
VDTNs are based on the principle of asynchronous communications, bundleoriented
communication from the DTN architecture, employing a store-carryand-
forward routing paradigm. In this sense, VDTNs should use the tight network
resources optimizing each opportunistic contact among nodes.
At the ingress edge nodes, incoming IP Packets (datagrams) are assembled
into large data packets, called bundles. The bundle aggregation process plays
an important role on the performance of VDTN applications. Then, this paper
presents three aggregation algorithms based on time, bundle size, and a hybrid
solution with combination of both. Furthermore, the following four aggregation
schemes with quality of service (QoS) support are proposed: 1) single-class bundle
with N = M, 2) composite-class bundle with N = M, 3) single-class bundle
with N > M, and 4) composite-class bundle with N > M, where N is the number
of classes of incoming packets and M is the number of priorities supported
by the VDTN core network. The proposed mechanisms were evaluated through
a laboratory testbed, called VDTN@Lab. The adaptive hybrid approach and the
composite-class schemes present the best performance for different types of
traffic load and best priorities distribution, respectively
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
PaFiR : Particle Filter Routing – a predictive relaying scheme for UAV-assisted IoT communications in future innovated networks
Increasing urbanization, smart cities and other cutting-edge technologies offer the prospect of providing more functions to benefit citizens by relying on the substantial data processing and exchange capabilities now possible. This can generate significant unpredictable and unbalanced data loads for the bearing IoT network to support its application and service demands. We thus propose a wireless routing scheme designed to use the Particle Filter algorithm to empower portable smart devices with intelligent capacities for the radio communication system. This facilitates the offloading of traffic from traditional wireless networks and enables the IoT system to adopt unmanned aerial vehicles, thus also offering further innovation to flying network platforms. The proposed PaFiR routing protocol offers the network more scalability, tolerance and resilience, to achieve the goal of smart relaying. Simulation results that demonstrate the routing algorithm designed offers excellent performance when compared with existing wireless relaying schemes. It provides delivery ratios that are improved by up to 40% without unmanageable increases in latency or overheads
Reliable Data Transmission in Challenging Vehicular Network using Delay Tolerant Network
In the 21st century, there has been an increasing tendency toward the wide adoption of wireless networks and technologies due to their significant advantages such as flexibility, mobility, accessibility, and low cost. Wireless technologies have therefore become essential factors in the improvement of intra-vehicle road safety in Vehicular Ad-hoc Network (VANET), which potentially reduce road traffic accidents by enabling efficient exchange of information between vehicles in the early stages. However, due to the inherent high mobility and rapid change of topology, there are numerous challenges in VANET. Hence, different software packages have been combined in this project to create the VANET environment, whereby the Objective Modular Network Testbed (OMNeT++) and the Simulation of Urban Mobility (SUMO), along with Vehicles in Network Simulation (VEINS) are integrated to model the VANET environment.
Also, Delay Tolerant Network (DTN) are implemented in the Opportunistic Network Environment (ONE) simulator, where the Store-Carry-Forward technique is used to route traffic. When network resources are not limited, a high delivery ratio is possible. However, when network resources are scarce, these protocols will have a low delivery ratio and high overhead. Due to these limitations, in this research, an extensive performance evaluation of various routing protocols for DTN with different buffer management policies, giving insight into the impact of these policies on DTN routing protocol performance has been conducted. The empirical study gave insight into the strengths and limitations of the existing protocols thus enabling the selection of the benchmark protocols utilized in evaluating a new Enhanced Message Replication Technique (EMRT) proposed in this thesis.
The main contribution of this thesis is the design, implementation, and evaluation of a novel EMRT that dynamically adjusts the number of message replicas based on a node's ability to quickly disseminate the message and maximize the delivery ratio. EMRT is evaluated using three different quota protocols: Spray&Wait, Encounter Based Routing (EBR), and Destination Based Routing Protocol (DBRP). Simulation results show that applying EMRT to these protocols improves the delivery ratio while reducing overhead ratio and latency average. For example, when combined with Spray&Wait, EBR, and DBRP, the delivery probability is improved by 13%, 8%, and 10%, respectively, while the latency average is reduced by 51%, 14%, and 13%, respectively