6,189 research outputs found
Applications of Repeated Games in Wireless Networks: A Survey
A repeated game is an effective tool to model interactions and conflicts for
players aiming to achieve their objectives in a long-term basis. Contrary to
static noncooperative games that model an interaction among players in only one
period, in repeated games, interactions of players repeat for multiple periods;
and thus the players become aware of other players' past behaviors and their
future benefits, and will adapt their behavior accordingly. In wireless
networks, conflicts among wireless nodes can lead to selfish behaviors,
resulting in poor network performances and detrimental individual payoffs. In
this paper, we survey the applications of repeated games in different wireless
networks. The main goal is to demonstrate the use of repeated games to
encourage wireless nodes to cooperate, thereby improving network performances
and avoiding network disruption due to selfish behaviors. Furthermore, various
problems in wireless networks and variations of repeated game models together
with the corresponding solutions are discussed in this survey. Finally, we
outline some open issues and future research directions.Comment: 32 pages, 15 figures, 5 tables, 168 reference
Performance evaluation of cooperation strategies for m-health services and applications
Health telematics are becoming a major improvement for patients’ lives, especially for
disabled, elderly, and chronically ill people. Information and communication technologies have
rapidly grown along with the mobile Internet concept of anywhere and anytime connection.
In this context, Mobile Health (m-Health) proposes healthcare services delivering, overcoming
geographical, temporal and even organizational barriers. Pervasive and m-Health services aim
to respond several emerging problems in health services, including the increasing number of
chronic diseases related to lifestyle, high costs in existing national health services, the need
to empower patients and families to self-care and manage their own healthcare, and the need
to provide direct access to health services, regardless the time and place. Mobile Health (m-
Health) systems include the use of mobile devices and applications that interact with patients
and caretakers. However, mobile devices have several constraints (such as, processor, energy,
and storage resource limitations), affecting the quality of service and user experience. Architectures
based on mobile devices and wireless communications presents several challenged issues
and constraints, such as, battery and storage capacity, broadcast constraints, interferences, disconnections,
noises, limited bandwidths, and network delays. In this sense, cooperation-based
approaches are presented as a solution to solve such limitations, focusing on increasing network
connectivity, communication rates, and reliability. Cooperation is an important research topic
that has been growing in recent years. With the advent of wireless networks, several recent
studies present cooperation mechanisms and algorithms as a solution to improve wireless networks
performance. In the absence of a stable network infrastructure, mobile nodes cooperate
with each other performing all networking functionalities. For example, it can support intermediate
nodes forwarding packets between two distant nodes.
This Thesis proposes a novel cooperation strategy for m-Health services and applications.
This reputation-based scheme uses a Web-service to handle all the nodes reputation and networking
permissions. Its main goal is to provide Internet services to mobile devices without
network connectivity through cooperation with neighbor devices. Therefore resolving the above
mentioned network problems and resulting in a major improvement for m-Health network architectures
performances. A performance evaluation of this proposal through a real network
scenario demonstrating and validating this cooperative scheme using a real m-Health application
is presented. A cryptography solution for m-Health applications under cooperative environments,
called DE4MHA, is also proposed and evaluated using the same real network scenario and
the same m-Health application. Finally, this work proposes, a generalized cooperative application
framework, called MobiCoop, that extends the incentive-based cooperative scheme for
m-Health applications for all mobile applications. Its performance evaluation is also presented
through a real network scenario demonstrating and validating MobiCoop using different mobile
applications
Game Theory-Based Cooperation for Underwater Acoustic Sensor Networks: Taxonomy, Review, Research Challenges and Directions.
Exploring and monitoring the underwater world using underwater sensors is drawing a lot of attention these days. In this field cooperation between acoustic sensor nodes has been a critical problem due to the challenging features such as acoustic channel failure (sound signal), long propagation delay of acoustic signal, limited bandwidth and loss of connectivity. There are several proposed methods to improve cooperation between the nodes by incorporating information/game theory in the node's cooperation. However, there is a need to classify the existing works and demonstrate their performance in addressing the cooperation issue. In this paper, we have conducted a review to investigate various factors affecting cooperation in underwater acoustic sensor networks. We study various cooperation techniques used for underwater acoustic sensor networks from different perspectives, with a concentration on communication reliability, energy consumption, and security and present a taxonomy for underwater cooperation. Moreover, we further review how the game theory can be applied to make the nodes cooperate with each other. We further analyze different cooperative game methods, where their performance on different metrics is compared. Finally, open issues and future research direction in underwater acoustic sensor networks are highlighted
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
Relaying in the Internet of Things (IoT): A Survey
The deployment of relays between Internet of Things (IoT) end devices and gateways can improve link quality. In cellular-based IoT, relays have the potential to reduce base station overload. The energy expended in single-hop long-range communication can be reduced if relays listen to transmissions of end devices and forward these observations to gateways. However, incorporating relays into IoT networks faces some challenges. IoT end devices are designed primarily for uplink communication of small-sized observations toward the network; hence, opportunistically using end devices as relays needs a redesign of both the medium access control (MAC) layer protocol of such end devices and possible addition of new communication interfaces. Additionally, the wake-up time of IoT end devices needs to be synchronized with that of the relays. For cellular-based IoT, the possibility of using infrastructure relays exists, and noncellular IoT networks can leverage the presence of mobile devices for relaying, for example, in remote healthcare. However, the latter presents problems of incentivizing relay participation and managing the mobility of relays. Furthermore, although relays can increase the lifetime of IoT networks, deploying relays implies the need for additional batteries to power them. This can erode the energy efficiency gain that relays offer. Therefore, designing relay-assisted IoT networks that provide acceptable trade-offs is key, and this goes beyond adding an extra transmit RF chain to a relay-enabled IoT end device. There has been increasing research interest in IoT relaying, as demonstrated in the available literature. Works that consider these issues are surveyed in this paper to provide insight into the state of the art, provide design insights for network designers and motivate future research directions
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