1,911 research outputs found
Markov Decision Processes with Applications in Wireless Sensor Networks: A Survey
Wireless sensor networks (WSNs) consist of autonomous and resource-limited
devices. The devices cooperate to monitor one or more physical phenomena within
an area of interest. WSNs operate as stochastic systems because of randomness
in the monitored environments. For long service time and low maintenance cost,
WSNs require adaptive and robust methods to address data exchange, topology
formulation, resource and power optimization, sensing coverage and object
detection, and security challenges. In these problems, sensor nodes are to make
optimized decisions from a set of accessible strategies to achieve design
goals. This survey reviews numerous applications of the Markov decision process
(MDP) framework, a powerful decision-making tool to develop adaptive algorithms
and protocols for WSNs. Furthermore, various solution methods are discussed and
compared to serve as a guide for using MDPs in WSNs
Fast Neighbor Discovery for Wireless Ad Hoc Network with Successive Interference Cancellation
Neighbor discovery (ND) is a key step in wireless ad hoc network, which
directly affects the efficiency of wireless networking. Improving the speed of
ND has always been the goal of ND algorithms. The classical ND algorithms lose
packets due to the collision of multiple packets, which greatly affects the
speed of the ND algorithms. Traditional methods detect packet collision and
implement retransmission when encountering packet loss. However, they does not
solve the packet collision problem and the performance improvement of ND
algorithms is limited. In this paper, the successive interference cancellation
(SIC) technology is introduced into the ND algorithms to unpack multiple
collision packets by distinguishing multiple packets in the power domain.
Besides, the multi-packet reception (MPR) is further applied to reduce the
probability of packet collision by distinguishing multiple received packets,
thus further improving the speed of ND algorithms. Six ND algorithms, namely
completely random algorithm (CRA), CRA based on SIC (CRA-SIC), CRA based on SIC
and MPR (CRA-SIC-MPR), scan-based algorithm (SBA), SBA based on SIC (SBA-SIC),
and SBA based on SIC and MPR (SBA-SIC-MPR), are theoretically analyzed and
verified by simulation. The simulation results show that SIC and MPR reduce the
ND time of SBA by 69.02% and CRA by 66.03% averagely.Comment: 16 pages, 16 figure
Cluster based jamming and countermeasures for wireless sensor network MAC protocols
A wireless sensor network (WSN) is a collection of wireless nodes, usually with limited computing resources and available energy. The medium access control layer (MAC layer) directly guides the radio hardware and manages access to the radio spectrum in controlled way. A top priority for a WSN MAC protocol is to conserve energy, however tailoring the algorithm for this purpose can create or expose a number of security vulnerabilities. In particular, a regular duty cycle makes a node vulnerable to periodic jamming attacks. This vulnerability limits the use of use of a WSN in applications requiring high levels of security. We present a new WSN MAC protocol, RSMAC (Random Sleep MAC) that is designed to provide resistance to periodic jamming attacks while maintaining elements that are essential to WSN functionality. CPU, memory and especially radio usage are kept to a minimum to conserve energy while maintaining an acceptable level of network performance so that applications can be run transparently on top of the secure MAC layer. We use a coordinated yet pseudo-random duty cycle that is loosely synchronized across the entire network via a distributed algorithm. This thwarts an attacker\u27s ability to predict when nodes will be awake and likewise thwarts energy efficient intelligent jamming attacks by reducing their effectiveness and energy-efficiency to that of non-intelligent attacks. Implementing the random duty cycle requires additional energy usage, but also offers an opportunity to reduce asymmetric energy use and eliminate energy use lost to explicit neighbor discovery. We perform testing of RSMAC against non-secure protocols in a novel simulator that we designed to make prototyping new WSN algorithms efficient, informative and consistent. First we perform tests of the existing SMAC protocol to demonstrate the relevance of the novel simulation for estimating energy usage, data transmission rates, MAC timing and other relevant macro characteristics of wireless sensor networks. Second, we use the simulation to perform detailed testing of RSMAC that demonstrates its performance characteristics with different configurations and its effectiveness in confounding intelligent jammers
Performance Assessment of Routing Protocols for IoT/6LoWPAN Networks
The Internet of Things (IoT) proposes a disruptive communication paradigm that allows
smart objects to exchange data among themselves to reach a common goal. IoT application
scenarios are multiple and can range from a simple smart home lighting system to fully controlled
automated manufacturing chains. In the majority of IoT deployments, things are equipped with
small devices that can suffer from severe hardware and energy restrictions that are responsible
for performing data processing and wireless communication tasks. Thus, due to their features,
communication networks that are used by these devices are generally categorized as Low Power
and Lossy Networks (LLNs).
The considerable variation in IoT applications represents a critical issue to LLN networks,
which should offer support to different requirements as well as keeping reasonable
quality-of-service (QoS) levels. Based on this challenge, routing protocols represent a key issue
in IoT scenarios deployment. Routing protocols are responsible for creating paths among devices
and their interactions. Hence, network performance and features are highly dependent
on protocol behavior. Also, based on the adopted protocol, the support for some specific requirements
of IoT applications may or may not be provided. Thus, a routing protocol should be
projected to attend the needs of the applications considering the limitations of the device that
will execute them.
Looking to attend the demand of routing protocols for LLNs and, consequently, for IoT
networks, the Internet Engineering Task Force (IETF) has designed and standardized the IPv6
Routing Protocol for Low Power and Lossy Networks (RPL). This protocol, although being robust
and offering features to fulfill the need of several applications, still presents several faults and
weaknesses (mainly related to its high complexity and memory requirement), which limits its
adoption in IoT scenarios. An alternative to RPL, the Lightweight On-demand Ad Hoc Distancevector
Routing Protocol â Next Generation (LOADng) has emerged as a less complicated routing
solution for LLNs. However, the cost of its simplicity is paid for with the absence of adequate
support for a critical set of features required for many IoT environments. Thus, based on the
challenging open issues related to routing in IoT networks, this thesis aims to study and propose
contributions to better attend the network requirements of IoT scenarios. A comprehensive survey,
reviewing state-of-the-art routing protocols adopted for IoT, identified the strengths and
weaknesses of current solutions available in the literature. Based on the identified limitations,
a set of improvements is designed to overcome these issues and enhance IoT network performance.
The novel solutions are proposed to include reliable and efficient support to attend
the needs of IoT applications, such as mobility, heterogeneity, and different traffic patterns.
Moreover, mechanisms to improve the network performance in IoT scenarios, which integrate
devices with different communication technologies, are introduced.
The studies conducted to assess the performance of the proposed solutions showed
the high potential of the proposed solutions. When the approaches presented in this thesis
were compared with others available in the literature, they presented very promising results
considering the metrics related to the Quality of Service (QoS), network and energy efficiency,
and memory usage as well as adding new features to the base protocols. Hence, it is believed
that the proposed improvements contribute to the state-of-the-art of routing solutions for IoT
networks, increasing the performance and adoption of enhanced protocols.A Internet das Coisas, do inglĂȘs Internet of Things (IoT), propĂ”e um paradigma de
comunicação disruptivo para possibilitar que dispositivos, que podem ser dotados de comportamentos
autónomos ou inteligentes, troquem dados entre eles buscando alcançar um objetivo
comum. Os cenårios de aplicação do IoT são muito variados e podem abranger desde um simples
sistema de iluminação para casa até o controle total de uma linha de produção industrial. Na
maioria das instalaçÔes IoT, as âcoisasâ sĂŁo equipadas com um pequeno dispositivo, responsĂĄvel
por realizar as tarefas de comunicação e processamento de dados, que pode sofrer com severas
restriçÔes de hardware e energia. Assim, devido Ă s suas caracterĂsticas, a rede de comunicação
criada por esses dispositivos Ă© geralmente categorizada como uma Low Power and Lossy Network
(LLN).
A grande variedade de cenĂĄrios IoT representam uma questĂŁo crucial para as LLNs,
que devem oferecer suporte aos diferentes requisitos das aplicaçÔes, alĂ©m de manter nĂveis
de qualidade de serviço, do inglĂȘs Quality of Service (QoS), adequados. Baseado neste desafio,
os protocolos de encaminhamento constituem um aspecto chave na implementação de
cenĂĄrios IoT. Os protocolos de encaminhamento sĂŁo responsĂĄveis por criar os caminhos entre
os dispositivos e permitir suas interaçÔes. Assim, o desempenho e as caracterĂsticas da rede
sĂŁo altamente dependentes do comportamento destes protocolos. Adicionalmente, com base
no protocolo adotado, o suporte a alguns requisitos especĂficos das aplicaçÔes de IoT podem
ou nĂŁo ser fornecidos. Portanto, estes protocolos devem ser projetados para atender as necessidades
das aplicaçÔes assim como considerando as limitaçÔes do hardware no qual serão
executados.
Procurando atender Ă s necessidades dos protocolos de encaminhamento em LLNs e,
consequentemente, das redes IoT, a Internet Engineering Task Force (IETF) desenvolveu e padronizou
o IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). O protocolo, embora
seja robusto e ofereça recursos para atender às necessidades de diferentes aplicaçÔes, apresenta
algumas falhas e fraquezas (principalmente relacionadas com a sua alta complexidade e
necessidade de memória) que limitam sua adoção em cenårios IoT. Em alternativa ao RPL, o
Lightweight On-demand Ad hoc Distance-vector Routing Protocol â Next Generation (LOADng)
emergiu como uma solução de encaminhamento menos complexa para as LLNs. Contudo, o
preço da simplicidade é pago com a falta de suporte adequado para um conjunto de recursos
essenciais necessårios em muitos ambientes IoT. Assim, inspirado pelas desafiadoras questÔes
ainda em aberto relacionadas com o encaminhamento em redes IoT, esta tese tem como objetivo
estudar e propor contribuiçÔes para melhor atender os requisitos de rede em cenårios IoT.
Uma profunda e abrangente revisĂŁo do estado da arte sobre os protocolos de encaminhamento
adotados em IoT identificou os pontos fortes e limitaçÔes das soluçÔes atuais. Com base nas debilidades
encontradas, um conjunto de soluçÔes de melhoria Ă© proposto para superar carĂȘncias
existentes e melhorar o desempenho das redes IoT. As novas soluçÔes são propostas para incluir
um suporte confiåvel e eficiente capaz atender às necessidades das aplicaçÔes IoT relacionadas
com suporte à mobilidade, heterogeneidade dos dispositivos e diferentes padrÔes de tråfego.
Além disso, são introduzidos mecanismos para melhorar o desempenho da rede em cenårios IoT
que integram dispositivos com diferentes tecnologias de comunicação.
Os vårios estudos realizados para mensurar o desempenho das soluçÔes propostas mostraram
o grande potencial do conjunto de melhorias introduzidas. Quando comparadas com
outras abordagens existentes na literatura, as soluçÔes propostas nesta tese demonstraram um aumento do desempenho consistente para métricas relacionadas a qualidade de serviço, uso de
memĂłria, eficiĂȘncia energĂ©tica e de rede, alĂ©m de adicionar novas funcionalidades aos protocolos
base. Portanto, acredita-se que as melhorias propostas contribuiem para o avanço do estado
da arte em soluçÔes de encaminhamento para redes IoT e aumentar a adoção e utilização dos
protocolos estudados
Airborne Directional Networking: Topology Control Protocol Design
This research identifies and evaluates the impact of several architectural design choices in relation to airborne networking in contested environments related to autonomous topology control. Using simulation, we evaluate topology reconfiguration effectiveness using classical performance metrics for different point-to-point communication architectures. Our attention is focused on the design choices which have the greatest impact on reliability, scalability, and performance. In this work, we discuss the impact of several practical considerations of airborne networking in contested environments related to autonomous topology control modeling. Using simulation, we derive multiple classical performance metrics to evaluate topology reconfiguration effectiveness for different point-to-point communication architecture attributes for the purpose of qualifying protocol design elements
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