695 research outputs found
FastM: Design and Evaluation of a Fast Mobility Mechanism for Wireless Mesh Networks
Although there is a large volume of work in the literature in terms of mobility approaches for Wireless Mesh Networks, usually these approaches introduce high latency in the handover process and do not support realtime services and applications. Moreover, mobility is decoupled from routing, which leads to inefficiency to both mobility and routing approaches with respect to mobility. In this paper we present a new extension to proactive routing protocols using a fast mobility extension, FastM, with the purpose of increasing handover performance in Wireless Mesh Networks. With this new extension, a new concept is created to integrate information between neighbor wireless mesh routers, managing locations of clients associated to wireless mesh routers in a certain neighborhood, and avoiding packet loss during handover. The proposed mobility approach is able to optimize the handover process without imposing any modifications to the current IEE 802.11 MAC protocol and use unmodified clients. Results show the improved efficiency of the proposed scheme: metrics such as disconnection time, throughput, packet loss and control overhead are largely improved when compared to previous approaches. Moreover, these conclusions apply to mobility scenarios, although mobility decreases the performance of the handover approach, as expected
Distribuição de vĂdeo para grupos de utilizadores em redes mĂłveis heterogĂ©neas19
The evolutions veri ed in mobile devices capabilities (storage capacity, screen
resolution, processor, etc.) over the last years led to a signi cant change
in mobile user behavior, with the consumption and creation of multimedia
content becoming more common, in particular video tra c. Consequently,
mobile operator networks, despite being the target of architectural evolutions
and improvements over several parameters (such as capacity, transmission
and reception performance, amongst others), also increasingly become more
frequently challenged by performance aspects associated to the nature of
video tra c, whether by the demanding requirements associated to that
service, or by its volume increase in such networks.
This Thesis proposes modi cations to the mobile architecture towards a more
e cient video broadcasting, de ning and developing mechanisms applicable
to the network, or to the mobile terminal. Particularly, heterogeneous
networks multicast IP mobility supported scenarios are focused, emphasizing
their application over di erent access technologies. The suggested changes
are applicable to mobile or static user scenarios, whether it performs the role
of receiver or source of the video tra c. Similarly, the de ned mechanisms
propose solutions targeting operators with di erent video broadcasting goals,
or whose networks have di erent characteristics. The pursued methodology
combined an experimental evaluation executed over physical testbeds,
with the mathematical evaluation using network simulation, allowing the
veri cation of its impact on the optimization of video reception in mobile
terminalsA evolução veri cada nas caracterĂsticas dos dispositivos moveis (capacidade
de armazenamento, resolução do ecrã, processador, etc.) durante os
últimos anos levou a uma alteração signi cativa nos comportamentos dos
utilizadores, sendo agora comum o consumo e produção de conteúdos
multimĂ©dia envolvendo terminais mĂłveis, em particular o tráfego vĂdeo.
Consequentemente, as redes de operador móvel, embora tendo também sido
alvo constante de evoluções arquitecturais e melhorias em vários parâmetros
(tais como capacidade, ritmo de transmissão/recepção, entre outros), vêemse
cada vez mais frequentemente desa adas por aspectos de desempenho
associados Ă natureza do tráfego de vĂdeo, seja pela exigĂŞncia de requisitos
associados a esse serviço, quer pelo aumento do volume do mesmo nesse
tipo de redes.
Esta Tese propĂ´e alterações Ă arquitetura mĂłvel para a disseminação de vĂdeo
mais e ciente, de nindo e desenvolvendo mecanismos aplicáveis à rede, ou
ao utilizador móvel. Em particular, são focados cenários suportados por IP
multicast em redes móveis heterogéneas, isto é, com ênfase na aplicação
destes mecanismos sobre diferentes tecnologias de acesso. As alterações
sugeridas aplicam-se a cenários de utilizador estático ou móvel, sendo este a
fonte ou receptor do tráfego vĂdeo. Da mesma forma, sĂŁo propostas soluções
tendo em vista operadores com diferentes objectivos de disseminação de
vĂdeo, ou cujas redes tĂŞm diferentes caracterĂsticas. A metodologia utilizada
combinou a avaliação experimental em testbeds fĂsicas com a avaliação
matemática em simulações de redes, e permitiu veri car o impacto sobre
a optimização da recepção de vĂdeo em terminais mĂłveisPrograma Doutoral em Telecomunicaçõe
MobiSplit: a Scalable Approach to Emerging Mobility Networks
First ACM/IEEE International Workshop on Mobility in the Evolving Internet Architecture. Session: Architectural issues. San Francisco, California, Dec. 01 2006This paper presents a novel architecture,
MobiSplit, to manage mobility in future IP based networks.
The proposed architecture separates mobility management in
two levels, local and global, that are managed in completely
independent ways. The paper describes the flexibility
advantages that this architecture brings to operators, and how
it is appropriate for the current trend to multiple and very
different access providers and operators. Heterogeneity,
support for seamless handovers and multihoming, and
scalability issues are analyzed in the paper
End-to-end QoS architecture for 4G scenarios
This paper describes the QoS architecture and the corresponding QoS signalling protocols to be developed inside the IST project Daidalos. We address the main results achieved in terms of the definition of the QoS components and its interfaces, the description of the application and network services, definition of the signalling scenarios for the integration of the QoS signalling with the application signalling and with mobility approaches, and specification of the intra- and inter- domain QoS control approaches. We also describe the QoS management of the system, through the Policy–based Management System, and a Real-time Network Monitoring system able to aid in admission control with the results of active and passive measurements. All the elements, interfaces and functionalities take into account multicast services and inherent broadcast networks
Multicast outing protocols and architectures in mobile ad-hoc wireless networks
The basic philosophy of personal communication services is to provide user-to-user, location independent communication services. The emerging group communication wireless applications, such as multipoint data dissemination and multiparty conferencing tools have made the design and development of efficient multicast techniques in mobile ad-hoc networking environments a necessity and not just a desire. Multicast protocols in mobile adhoc networks have been an area of active research for the past few years.
In this dissertation, protocols and architectures for supporting multicast services are proposed, analyzed and evaluated in mobile ad-hoc wireless networks. In the first chapter, the activities and recent advances are summarized in this work-in-progress area by identifying the main issues and challenges that multicast protocols are facing in mobile ad-hoc networking environments and by surveying several existing multicasting protocols. a classification of the current multicast protocols is presented, the functionality of the individual existing protocols is discussed, and a qualitative comparison of their characteristics is provided according to several distinct features and performance parameters.
In the second chapter, a novel mobility-based clustering strategy that facilitates the support of multicast routing and mobility management is presented in mobile ad-hoc networks. In the proposed structure, mobile nodes are organized into nonoverlapping clusters which have adaptive variable-sizes according to their respective mobility. The mobility-based clustering (MBC) approach which is proposed uses combination of both physical and logical partitions of the network (i.e. geographic proximity and functional relation between nodes, such as mobility pattern etc.).
In the third chapter, an entropy-based modeling framework for supporting and evaluating the stability is proposed in mobile ad-hoc wireless networks. The basic motivations of the proposed modeling approach stem from the commonality observed in the location uncertainty in mobile ad-hoc wireless networks and the concept of entropy.
In the fourth chapter, a Mobility-based Hybrid Multicast Routing (MHMR) protocol suitable for mobile ad-hoc networks is proposed. The MHMR uses the MBC algorithm as the underlying structure. The main features that the proposed protocol introduces are the following: a) mobility based clustering and group based hierarchical structure, in order to effectively support the stability and scalability, b) group based (limited) mesh structure and forwarding tree concepts, in order to support the robustness of the mesh topologies which provides limited redundancy and the efficiency of tree forwarding simultaneously, and c) combination of proactive and reactive concepts which provide the low route acquisition delay of proactive techniques and the low overhead of reactive methods.
In the fifth chapter, an architecture for supporting geomulticast services with high message delivery accuracy is presented in mobile ad-hoc wireless networks. Geomulticast is a specialized location-dependent multicasting technique, where messages are multicast to some specific user groups within a specific zone. An analytical framework which is used to evaluate the various geomulticast architectures and protocols is also developed and presented. The last chapter concludes the dissertation
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