41 research outputs found
IP multicast receiver mobility support using PMIPv6 in a global satellite network
YesA new generation of satellite systems that support regenerative on-board processors (OBPs) and multiple spot beam technology have opened new and efficient possibilities of implementing IP multicast communication over satellites. These new features have widened the scope of satellite-based applications and also enable satellite operators to efficiently utilize their allocated bandwidth resources. This makes it possible to provide cost effective satellite network services. IP multicast is a network layer protocol designed for group communication to save bandwidth resources and reduce processing overhead on the source side. The inherent broadcast nature of satellites, their global coverage (air, land, and sea), and direct access to a large number of subscribers imply satellites have unrivalled advantages in supporting IP multicast applications. IP mobility support in general and IP mobile multicast support in particular on mobile satellite terminals like the ones mounted on long haul flights, maritime vessels, continental trains, etc., still remain big challenges that have received very little attention from the research community. This paper proposes how Proxy Mobile IPv6 (PMIPv6)-based IP multicast mobility support defined for terrestrial networks can be adopted and used to support IP mobile multicast in future satellite networks, taking cognizance of the trend in the evolution of satellite communications
Multicast source mobility support for regenerative satellite networks
YesSatellite communications provides an effective solution to the ever increasing demand for mobile and ubiquitous communications especially in areas where terrestrial communication infrastructure is not present. IP multicasting is a bandwidth saving technology which could become an indispensable means of group communication over satellites since it can utilise the scarce and expensive satellite resources in an efficient way. In Source-Specific Multicast (SSM) the data is sent through a multicast tree from the source to all the receivers. However, if a source is a mobile node moving from one network to another, then special mechanisms are required to make sure this multicast tree does not break. Until now, while many research efforts have been made to provide IP multicast for the mobile nodes, they are mainly focused on terrestrial networks. Unfortunately, the terrestrial mobile multicast schemes are not directly applicable in a satellite environment. This paper, proposes a new mechanism to support multicast source mobility in SSM based applications for a mesh multi-beam satellite network with receivers both within the satellite network and in the Internet. In the proposed mechanism, the SSM receivers continue to receive multicast traffic from the mobile source despite the fact that the IP address of the source keeps on changing as it changes its point of attachment from one satellite gateway (GW) to another. The proposed scheme is evaluated and the results compared with the mobile IP home subscription (MIP HS)-based approach. The results show that the proposed scheme outperforms the MIP HS-based approach in terms of signalling cost and packet delivery cost
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IP Mobile Multicast over Next Generation Satellite Networks. Design and Evaluation of a Seamless Mobility Framework for IP Multicast Communications over a Multi-beam Geostationary Satellite Network
The inherent broadcast nature of satellites, their global coverage and direct
access to a large number of subscribers give satellites unrivalled advantages in
supporting IP multicast applications. A new generation of satellite systems that
support regenerative on-board processors and multiple spot beam technology
have opened new possibilities of implementing IP multicast communication over
satellites. These new features enable satellites to make efficient use of their
allocated bandwidth resources and provide cost effective network services but
equally, create new challenges for mobile satellite terminals. IP mobility support
in general and IP mobile multicast support in particular on mobile satellite
terminals like the ones mounted on continental flights, maritime vessels, etc.,
still remain big challenges that have received very little attention from the
research community.
Up till now, there are no proposed mechanisms to support IP multicast for
mobile receivers/sources in multi-beam satellite networks in open literature.
This study explores the suitability of IP multicast mobility support schemes
defined for terrestrial networks in a satellite environment and proposes novel
schemes based on the concepts of Home and Remote subscription-based approaches, multiple interface and PMIPv6 protocol. Detailed analysis and
comparison of results obtained from the proposed schemes, Mobile IP (MIP)
Home and Remote subscription-based approaches (for terrestrial networks)
when implemented on a reference multi-beam satellite network are presented.
From these results, the proposed schemes outperform the MIP Home and
Remote subscription-based approaches in terms of gateway handover latency,
number of multicast packets lost and signalling cost over the satellite air
interface
Location Management in IP-based Future LEO Satellite Networks: A Review
Future integrated terrestrial, aerial, and space networks will involve
thousands of Low Earth Orbit (LEO) satellites forming a network of
mega-constellations, which will play a significant role in providing
communication and Internet services everywhere, at any time, and for
everything. Due to its very large scale and highly dynamic nature, future LEO
satellite networks (SatNets) management is a very complicated and crucial
process, especially the mobility management aspect and its two components
location management and handover management. In this article, we present a
comprehensive and critical review of the state-of-the-art research in LEO
SatNets location management. First, we give an overview of the Internet
Engineering Task Force (IETF) mobility management standards (e.g., Mobile IPv6
and Proxy Mobile IPv6) and discuss their location management techniques
limitations in the environment of future LEO SatNets. We highlight future LEO
SatNets mobility characteristics and their challenging features and describe
two unprecedented future location management scenarios. A taxonomy of the
available location management solutions for LEO SatNets is presented, where the
solutions are classified into three approaches. The "Issues to consider"
section draws attention to critical points related to each of the reviewed
approaches that should be considered in future LEO SatNets location management.
To identify the gaps, the current state of LEO SatNets location management is
summarized. Noteworthy future research directions are recommended. This article
is providing a road map for researchers and industry to shape the future of LEO
SatNets location management.Comment: Submitted to the Proceedings of the IEE
Future Trends and Challenges for Mobile and Convergent Networks
Some traffic characteristics like real-time, location-based, and
community-inspired, as well as the exponential increase on the data traffic in
mobile networks, are challenging the academia and standardization communities
to manage these networks in completely novel and intelligent ways, otherwise,
current network infrastructures can not offer a connection service with an
acceptable quality for both emergent traffic demand and application requisites.
In this way, a very relevant research problem that needs to be addressed is how
a heterogeneous wireless access infrastructure should be controlled to offer a
network access with a proper level of quality for diverse flows ending at
multi-mode devices in mobile scenarios. The current chapter reviews recent
research and standardization work developed under the most used wireless access
technologies and mobile access proposals. It comprehensively outlines the
impact on the deployment of those technologies in future networking
environments, not only on the network performance but also in how the most
important requirements of several relevant players, such as, content providers,
network operators, and users/terminals can be addressed. Finally, the chapter
concludes referring the most notable aspects in how the environment of future
networks are expected to evolve like technology convergence, service
convergence, terminal convergence, market convergence, environmental awareness,
energy-efficiency, self-organized and intelligent infrastructure, as well as
the most important functional requisites to be addressed through that
infrastructure such as flow mobility, data offloading, load balancing and
vertical multihoming.Comment: In book 4G & Beyond: The Convergence of Networks, Devices and
Services, Nova Science Publishers, 201
Quality of service aware data dissemination in vehicular Ad Hoc networks
Des systèmes de transport intelligents (STI) seront éventuellement fournis dans un proche avenir pour la sécurité et le confort des personnes lors de leurs déplacements sur les routes. Les réseaux ad-hoc véhiculaires (VANETs) représentent l'élément clé des STI. Les VANETs sont formés par des véhicules qui communiquent entre eux et avec l'infrastructure. En effet, les véhicules pourront échanger des messages qui comprennent, par exemple, des informations sur la circulation routière, les situations d'urgence et les divertissements. En particulier, les messages d'urgence sont diffusés par des véhicules en cas d'urgence (p.ex. un accident de voiture); afin de permettre aux conducteurs de réagir à temps (p.ex., ralentir), les messages d'urgence doivent être diffusés de manière fiable dans un délai très court. Dans les VANETs, il existe plusieurs facteurs, tels que le canal à pertes, les terminaux cachés, les interférences et la bande passante limitée, qui compliquent énormément la satisfaction des exigences de fiabilité et de délai des messages d'urgence. Dans cette thèse, en guise de première contribution, nous proposons un schéma de diffusion efficace à plusieurs sauts, appelé Dynamic Partitioning Scheme (DPS), pour diffuser les messages d'urgence. DPS calcule les tailles de partitions dynamiques et le calendrier de transmission pour chaque partition; à l'intérieur de la zone arrière de l'expéditeur, les partitions sont calculées de sorte qu'en moyenne chaque partition contient au moins un seul véhicule; l'objectif est de s'assurer que seul un véhicule dans la partition la plus éloignée (de l'expéditeur) est utilisé pour diffuser le message, jusqu'au saut suivant; ceci donne lieu à un délai d'un saut plus court. DPS assure une diffusion rapide des messages d'urgence. En outre, un nouveau mécanisme d'établissement de liaison, qui utilise des tonalités occupées, est proposé pour résoudre le problème du problème de terminal caché.
Dans les VANETs, la Multidiffusion, c'est-à-dire la transmission d'un message d'une source à un nombre limité de véhicules connus en tant que destinations, est très importante. Par rapport à la diffusion unique, avec Multidiffusion, la source peut simultanément prendre en charge plusieurs destinations, via une arborescence de multidiffusion, ce qui permet d'économiser de la bande passante et de réduire la congestion du réseau. Cependant, puisque les VANETs ont une topologie dynamique, le maintien de la connectivité de l'arbre de multidiffusion est un problème majeur. Comme deuxième contribution, nous proposons deux approches pour modéliser l'utilisation totale de bande passante d'une arborescence de multidiffusion: (i) la première approche considère le nombre de segments de route impliqués dans l'arbre de multidiffusion et (ii) la seconde approche considère le nombre d'intersections relais dans l'arbre de multidiffusion. Une heuristique est proposée pour chaque approche. Pour assurer la qualité de service de l'arbre de multidiffusion, des procédures efficaces sont proposées pour le suivi des destinations et la surveillance de la qualité de service des segments de route.
Comme troisième contribution, nous étudions le problème de la congestion causée par le routage du trafic de données dans les VANETs. Nous proposons (1) une approche de routage basée sur l’infonuagique qui, contrairement aux approches existantes, prend en compte les chemins de routage existants qui relaient déjà les données dans les VANETs. Les nouvelles demandes de routage sont traitées de sorte qu'aucun segment de route ne soit surchargé par plusieurs chemins de routage croisés. Au lieu d'acheminer les données en utilisant des chemins de routage sur un nombre limité de segments de route, notre approche équilibre la charge des données en utilisant des chemins de routage sur l'ensemble des tronçons routiers urbains, dans le but d'empêcher, dans la mesure du possible, les congestions locales dans les VANETs; et (2) une approche basée sur le réseau défini par logiciel (SDN) pour surveiller la connectivité VANET en temps réel et les délais de transmission sur chaque segment de route. Les données de surveillance sont utilisées en entrée de l'approche de routage.Intelligent Transportation Systems (ITS) will be eventually provided in the near future for both safety and comfort of people during their travel on the roads. Vehicular ad-hoc Networks (VANETs), represent the key component of ITS. VANETs consist of vehicles that communicate with each other and with the infrastructure. Indeed, vehicles will be able to exchange messages that include, for example, information about road traffic, emergency situations, and entertainment. Particularly, emergency messages are broadcasted by vehicles in case of an emergency (e.g., car accident); in order to allow drivers to react in time (e.g., slow down), emergency messages must be reliably disseminated with very short delay. In VANETs, there are several factors, such as lossy channel, hidden terminals, interferences and scarce bandwidth, which make satisfying reliability and delay requirements of emergency messages very challenging. In this thesis, as the first contribution, we propose a reliable time-efficient and multi-hop broadcasting scheme, called Dynamic Partitioning Scheme (DPS), to disseminate emergency messages. DPS computes dynamic partition sizes and the transmission schedule for each partition; inside the back area of the sender, the partitions are computed such that in average each partition contains at least a single vehicle; the objective is to ensure that only a vehicle in the farthest partition (from the sender) is used to disseminate the message, to next hop, resulting in shorter one hop delay. DPS ensures fast dissemination of emergency messages. Moreover, a new handshaking mechanism, that uses busy tones, is proposed to solve the problem of hidden terminal problem.
In VANETs, Multicasting, i.e. delivering a message from a source to a limited known number of vehicles as destinations, is very important. Compared to Unicasting, with Multicasting, the source can simultaneously support multiple destinations, via a multicast tree, saving bandwidth and reducing overall communication congestion. However, since VANETs have a dynamic topology, maintaining the connectivity of the multicast tree is a major issue. As the second contribution, we propose two approaches to model total bandwidth usage of a multicast tree: (i) the first approach considers the number of road segments involved in the multicast tree and (ii) the second approach considers the number of relaying intersections involved in the multicast tree. A heuristic is proposed for each approach. To ensure QoS of the multicasting tree, efficient procedures are proposed for tracking destinations and monitoring QoS of road segments.
As the third contribution, we study the problem of network congestion in routing data traffic in VANETs. We propose (1) a Cloud-based routing approach that, in opposition to existing approaches, takes into account existing routing paths which are already relaying data in VANETs. New routing requests are processed such that no road segment gets overloaded by multiple crossing routing paths. Instead of routing over a limited set of road segments, our approach balances the load of communication paths over the whole urban road segments, with the objective to prevent, whenever possible, local congestions in VANETs; and (2) a Software Defined Networking (SDN) based approach to monitor real-time VANETs connectivity and transmission delays on each road segment. The monitoring data is used as input to the routing approach
Quality-Driven Cross-Layer Protocols for Video Streaming over Vehicular Ad-Hoc Networks
The emerging vehicular ad-hoc networks (VANETs) offer a variety of applications
and new potential markets related to safety, convenience and entertainment, however,
they suffer from a number of challenges not shared so deeply by other types of existing
networks, particularly, in terms of mobility of nodes, and end-to-end quality of service
(QoS) provision. Although several existing works in the literature have attempted to
provide efficient protocols at different layers targeted mostly for safety applications, there remain many barriers to be overcome in order to constrain the widespread use of such networks for non-safety applications, specifically, for video streaming: 1) impact of high
speed mobility of nodes on end-to-end QoS provision; 2) cross-layer protocol design while keeping low computational complexity; 3) considering customer-oriented QoS metrics in the design of protocols; and 4) maintaining seamless single-hop and multi-hop connection between the destination vehicle and the road side unit (RSU) while network is moving.
This thesis addresses each of the above limitations in design of cross-layer protocols for video streaming application. 1) An adaptive MAC retransmission limit selection scheme is proposed to improve the performance of IEEE 802.11p standard MAC protocol for video streaming applications over VANETs. A multi-objective optimization framework, which jointly minimizes the probability of playback freezes and start-up delay of the streamed video at the destination vehicle by tuning the MAC retransmission limit with respect to channel statistics as well as packet transmission rate, is applied at road side unit (RSU). Two-hop transmission is applied in zones in which the destination
vehicle is not within the transmission range of any RSU. In the multi-hop scenario, we
discuss the computation of access probability used in the MAC adaptation scheme and propose a cross-layer path selection scheme; 2) We take advantage of similarity between multi-hop urban VANETs in dense traffic conditions and mesh connected networks. First, we investigate an application-centric routing scheme for video streaming over mesh connected overlays. Next, we introduce the challenges of urban VANETs compared to mesh networks and extend the proposed scheme in mesh network into a protocol for urban VANETs. A classification-based method is proposed to select an optimal path for video streaming over multi-hop mesh networks. The novelty is to translate the path selection
over multi-hop networks to a standard classification problem. The classification is based on minimizing average video packet distortion at the receiving nodes. The classifiers are trained offline using a vast collection of video sequences and wireless channel conditions in order to yield optimal performance during real time path selection. Our method substantially reduces the complexity of conventional exhaustive optimization methods and results in high quality (low distortion). Next, we propose an application-centric routing scheme for real-time video transmission over urban multi-hop vehicular ad-hoc network
(VANET) scenarios. Queuing based mobility model, spatial traffic distribution and prob-
ability of connectivity for sparse and dense VANET scenarios are taken into consideration
in designing the routing protocol. Numerical results demonstrate the gain achieved by
the proposed routing scheme versus geographic greedy forwarding in terms of video frame distortion and streaming start-up delay in several urban communication scenarios for various vehicle entrance rate and traffic densities; and 3) finally, the proposed quality-driven
routing scheme for delivering video streams is combined with a novel IP management
scheme. The routing scheme aims to optimize the visual quality of the transmitted video
frames by minimizing the distortion, the start-up delay, and the frequency of the streaming freezes. As the destination vehicle is in motion, it is unrealistic to assume that the vehicle will remain connected to the same access router (AR) for the whole trip. Mobile IP management schemes can benefit from the proposed multi-hop routing protocol in order to adapt proxy mobile IPv6 (PMIPv6) for multi-hop VANET for video streaming applications. The proposed cross-layer protocols can significantly improve the video streaming quality in terms of the number of streaming freezes and start-up delay over VANETs while achieving low computational complexity by using pattern classification methods for optimization
Utilização de diferentes tecnologias em redes de veículos
Mestrado em Engenharia Eletrónica e TelecomunicaçõesCom o surgimento de notícias relacionadas com carros autónomos, torna-se
óbvio que as Redes Veiculares vão ter um papel chave num futuro muito
próximo. Para além disso, estas redes podem ser utilizadas para fornecer
serviços de entretenimento para os passageiros dos veículos (Internet sem
recurso a tecnologia celular). Os maiores desa os relacionados com este
tipo de redes estão associados com a extrema mobilidade que os nós têm,
as constantes quebras de ligação e as perdas de tráfego devido à degradação
do sinal das redes wireless, que num ambiente repleto de obstáctulos como
é uma cidade, são uma constate.
Outro desa o/oportunidade é possibilitar que este tipo de redes tirem partido
de todos os recursos disponíveis, isto é, como hoje em dia as cidades estão
repletas de redes wireless, os nós têm de ter inteligência de selecionar a/as
rede/redes que fazem sentido, e encaminhar o tráfego através dessas mesmas
redes, tendo em conta a carga de cada rede. O objetivo desta dissertação vai
ser resolver/minorar os problemas acima descritos. Em primeira instância,
e com o objetivo de aumentar a e ciência de uma VANET já desenvolvida
no nosso grupo, foi criado um gestor de conectividade do tráfego de uplink,
que é capaz de diferenciar o tráfego, e depois dividido através das redes
de acesso, tendo em conta a carga de cada uma. Isto é suportado quer
quando o carro tem acesso direto à infraestrutura ou quando tem acesso
indireto (quando existe outro carro a agir com midle-man). Para melhorar a
performance da VANET em momentos de quebra de ligação, foi criada uma
mensagem de perda de ligação que, quando o sinal da ligação se aproxima
para níveis considerados maus informa a unidade responsável por dividir o
tráfego pelas redes de acesso, que determinada ligação é má, e não é para
ser usada.
Por m, para resolver o problema das perdas relacionadas com as ligações
sem os, optou-se por utilizar o network coding. O maior desa o foi tornar
a utilização do network coding transparente para o protocolo de mobilidade.
Por outras palavras, criar um programa que, de forma independente, trata
de todos os aspetos relacionado com a codi cação/descodi cação e deixar
para o protocolo de mobilidade os aspetos relacionados com a gestão da
mobilidade.
Para validar todo o trabalho feito, foram realizados testes de laboratório
(gestor de ligações de uplink e network coding) e testes de reais (mensagem
de perda de ligação). Os testes de laboratório mostraram que o tráfego de
uplink é dividido com sucesso, e que o gestor de conetividade envia o tráfego
para as redes de acesso tendo em conta a carga de cada uma, quer em single,
quer em multi-hop.
Relativamente aos testes reais, foi demonstrado que a mensagem de perda
de ligação permite diminuir perdas associadas ao processe de handovers.
Por m, relativamente ao network coding foi possível concluir que este permite
recuperar de perda de pacotes. Além disto, foi demostrado que esta
implementação suporta mobilidade e multihoming quer em single quer em
multi-hop.ehicular networks will have a key role in a near future. Furthermore, these
networks can be utilized to provide entertainment services (Internet) to the
car passengers. The greater challenges related with this kind of networks
are associated with the high mobility that the nodes have, the constant drop
of connectivity and to the tra c losses due the signal degradation of the
wireless networks, due to the huge amount of obstacles presented in the
city. Another challenge/opportunity is the possibility of these networks to
take advantage of all the available resources available. Nowadays the cities
have networks available almost everywhere, the nodes must have intelligence
to select the network/networks that make sense, and manage the routing
through those networks, taking into account the load of each access network.
The objective of this dissertation will be to solve/reduce the problems described
above. At the rst instance, the objective is to improve the vehicular
network already developed in our group, that already has a multihoming
framework that allows the downlink tra c to be divided through the available
networks, in a way that optimizes the network performance.
In order to also provide multihoming in uplink, in this dissertation it was
developed an uplink connection manager that can di erentiate the tra c
and route that tra c through di erent access networks at the same time,
taking into account the load of each network. This can be done in single
and multi-hop.
In order to improve the multihoming framework, it was developed a message
that informs the entity responsible for dividing the tra c that the connections
with bad signal quality should not be used to route tra c. This will allow
that entity to route the tra c through the other available networks with a
good signal quality, avoiding packet losses that would occur due bad signal
quality and connection losses.
Finally, in order to recover from packet losses due to bad network signal
quality, it was used network coding. The greatest challenge was to create
a network coding approach, that was transparent to the mobility protocol,
that, in an independent way manages all the aspects related to the encoding/
decoding and leave to the mobility protocol the management of all the
mobility related aspects. It were also developed two algorithms that nd the
con gurations to the encoding process. One of the algorithms will try to
ensure the maximum packet loss recovery, and the other will try to assure a
packet loss lower than a threshold, with the minimum overhead possible.
In order to evaluate all the work done in this dissertation, it were performed
laboratory tests (uplink manager and network coding) and real world tests
(disconnect message). These tests show that the uplink manager is able
to di erentiate tra c, and route through di erent access networks at the
same time, taking into account the load of each network (in single and
multi-hop). The tests related with the disconnect message show that this
message removes the packet loss that would normally occur in the handover
mechanisms. Finally, the network coding tests show that the network coding
can be used to recover from packet loss, even in a vehicular network with
multihoming and in single/multi-hop. Moreover, it was possible to conclude
that the two developed algorithms accomplish all the proposed objectives