173 research outputs found
Adoption of vehicular ad hoc networking protocols by networked robots
This paper focuses on the utilization of wireless networking in the robotics domain. Many researchers have already equipped their robots with wireless communication capabilities, stimulated by the observation that multi-robot systems tend to have several advantages over their single-robot counterparts. Typically, this integration of wireless communication is tackled in a quite pragmatic manner, only a few authors presented novel Robotic Ad Hoc Network (RANET) protocols that were designed specifically with robotic use cases in mind. This is in sharp contrast with the domain of vehicular ad hoc networks (VANET). This observation is the starting point of this paper. If the results of previous efforts focusing on VANET protocols could be reused in the RANET domain, this could lead to rapid progress in the field of networked robots. To investigate this possibility, this paper provides a thorough overview of the related work in the domain of robotic and vehicular ad hoc networks. Based on this information, an exhaustive list of requirements is defined for both types. It is concluded that the most significant difference lies in the fact that VANET protocols are oriented towards low throughput messaging, while RANET protocols have to support high throughput media streaming as well. Although not always with equal importance, all other defined requirements are valid for both protocols. This leads to the conclusion that cross-fertilization between them is an appealing approach for future RANET research. To support such developments, this paper concludes with the definition of an appropriate working plan
A Fair and Secure Cluster Formation Process for Ad Hoc Networks
An efficient approach for organizing large ad hoc networks is to divide the nodes
into multiple clusters and designate, for each cluster, a clusterhead which is responsible for
holding intercluster control information. The role of a clusterhead entails rights and duties.
On the one hand, it has a dominant position in front of the others because it manages the
connectivity and has access to other node¿s sensitive information. But on the other hand, the
clusterhead role also has some associated costs. Hence, in order to prevent malicious nodes
from taking control of the group in a fraudulent way and avoid selfish attacks from suitable
nodes, the clusterhead needs to be elected in a secure way. In this paper we present a novel
solution that guarantees the clusterhead is elected in a cheat-proof manner
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
Contribution to Research on Underwater Sensor Networks Architectures by Means of Simulation
El concepto de entorno inteligente concibe un mundo donde los diferentes tipos
de dispositivos inteligentes colaboran para conseguir un objetivo común. En este
concepto, inteligencia hace referencia a la habilidad de adquirir conocimiento
y aplicarlo de forma autónoma para conseguir el objetivo común, mientras que
entorno hace referencia al mundo físico que nos rodea. Por tanto, un entorno inteligente
se puede definir como aquel que adquiere conocimiento de su entorno y
aplicándolo permite mejorar la experiencia de sus habitantes.
La computación ubicua o generalizada permitirá que este concepto de entorno
inteligente se haga realidad. Normalmente, el término de computación ubicua hace
referencia al uso de dispositivos distribuidos por el mundo físico, pequeños y de
bajo precio, que pueden comunicarse entre ellos y resolver un problema de forma
colaborativa.
Cuando esta comunicación se lleva a cabo de forma inalámbrica, estos dispositivos
forman una red de sensores inalámbrica o en inglés, Wireless Sensor Network
(WSN). Estas redes están atrayendo cada vez más atención debido al amplio espectro
de aplicaciones que tienen, des de soluciones para el ámbito militar hasta
aplicaciones para el gran consumo.
Esta tesis se centra en las redes de sensores inalámbricas y subacuáticas o en
inglés, Underwater Wireless Sensor Networks (UWSN). Estas redes, a pesar de
compartir los mismos principios que las WSN, tienen un medio de transmisión
diferente que cambia su forma de comunicación de ondas de radio a ondas acústicas.
Este cambio hace que ambas redes sean diferentes en muchos aspectos como el
retardo de propagación, el ancho de banda disponible, el consumo de energía,
etc. De hecho, las señales acústicas tienen una velocidad de propagación cinco
órdenes de magnitud menor que las señales de radio. Por tanto, muchos algoritmos
y protocolos necesitan adaptarse o incluso rediseñarse.
Como el despliegue de este tipo de redes puede ser bastante complicado y caro,
se debe planificar de forma precisa el hardware y los algoritmos que se necesitan.
Con esta finalidad, las simulaciones pueden resultar una forma muy conveniente de probar todas las variables necesarias antes del despliegue de la aplicación. A
pesar de eso, un nivel de precisión adecuado que permita extraer resultados y
conclusiones confiables, solamente se puede conseguir utilizando modelos precisos
y parámetros reales.
Esta tesis propone un ecosistema para UWSN basado en herramientas libres y de
código abierto. Este ecosistema se compone de un modelo de recolección de energía
y unmodelo de unmódemde bajo coste y bajo consumo con un sistema de activación
remota que, junto con otros modelos ya implementados en las herramientas,
permite la realización de simulaciones precisas con datos ambientales del tiempo
y de las condiciones marinas del lugar donde la aplicación objeto de estudio va a
desplegarse.
Seguidamente, este ecosistema se utiliza con éxito en el estudio y evaluación de
diferentes protocolos de transmisión aplicados a una aplicación real de monitorización
de una piscifactoría en la costa del mar Mediterráneo, que es parte de un
proyecto de investigación español (CICYT CTM2011-2961-C02-01). Finalmente,
utilizando el modelo de recolección de energía, esta plataforma de simulación se
utiliza para medir los requisitos de energía de la aplicación y extraer las necesidades
de hardware mínimas.Climent Bayarri, JS. (2014). Contribution to Research on Underwater Sensor Networks Architectures by Means of Simulation [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/3532
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Advanced mobile networking, sensing, and controls.
This report describes an integrated approach for designing communication, sensing, and control systems for mobile distributed systems. Graph theoretic methods are used to analyze the input/output reachability and structural controllability and observability of a decentralized system. Embedded in each network node, this analysis will automatically reconfigure an ad hoc communication network for the sensing and control task at hand. The graph analysis can also be used to create the optimal communication flow control based upon the spatial distribution of the network nodes. Edge coloring algorithms tell us that the minimum number of time slots in a planar network is equal to either the maximum number of adjacent nodes (or degree) of the undirected graph plus some small number. Therefore, the more spread out that the nodes are, the fewer number of time slots are needed for communication, and the smaller the latency between nodes. In a coupled system, this results in a more responsive sensor network and control system. Network protocols are developed to propagate this information, and distributed algorithms are developed to automatically adjust the number of time slots available for communication. These protocols and algorithms must be extremely efficient and only updated as network nodes move. In addition, queuing theory is used to analyze the delay characteristics of Carrier Sense Multiple Access (CSMA) networks. This report documents the analysis, simulation, and implementation of these algorithms performed under this Laboratory Directed Research and Development (LDRD) effort
Performance Optimization in Wireless Local Area Networks
Wireless Local Area Networks (WLAN) are becoming more and more important
for providing wireless broadband access. Applications and networking
scenarios evolve continuously and in an unpredictable way, attracting the
attention of academic institutions, research centers and industry. For designing
an e cient WLAN is necessary to carefully plan coverage and to
optimize the network design parameters, such as AP locations, channel assignment,
power allocation, MAC protocol, routing algorithm, etc... In this
thesis we approach performance optimization in WLAN at di erent layer
of the OSI model. Our rst approach is at Network layer. Starting from
a Hybrid System modeling the
ow of tra c in the network, we propose a
Hybrid Linear Varying Parameter algorithm for identifying the link quality
that could be used as metric in routing algorithms. Go down to Data Link,
it is well known that CSMA (Carrier Sense Multiple Access) protocols exhibit
very poor performance in case of multi-hop transmissions, because of
inter-link interference due to imperfect carrier sensing. We propose two novel
algorithms, that are combining Time Division Multiple Access for grouping
contending nodes in non-interfering sets with Carrier Sense Multiple Access
for managing the channel access behind a set. In the rst solution, a game
theoretical study of intra slot contention is introduced, in the second solution
we apply an optimization algorithm to nd the optimal degree between
contention and scheduling. Both the presented solutions improve the network
performance with respect to CSMA and TDMA algorithms. Finally we
analyze the network performance at Physical Layer. In case of WLAN, we
can only use three orthogonal channels in an unlicensed spectrum, so the frequency
assignments should be subject to frequent adjustments, according to
the time-varying amount of interference which is not under the control of the
provider. This problem make necessary the introduction of an automatic network
planning solution, since a network administrator cannot continuously
monitor and correct the interference conditions su ered in the network. We
propose a novel protocol based on a distributed machine learning mechanism
in which the nodes choose, automatically and autonomously in each time
slot, the optimal channel for transmitting through a weighted combination
of protocols
Wake-up timer and binary exponential backoff for ZigBee-based wireless sensor network for flexible movement control system of a self-lifting scaffold
Synchronous movement of attached self-lifting scaffolds is traditionally monitored with wired sensors in high-rise building construction, which limits their flexibility of movements. A ZigBee-based wireless sensor system has been suggested in this article to prove the effectiveness of wireless sensor networks in actual implementation. Two optoelectronic sensors are integrated into a ZigBee node for measuring the displacement of attached self-lifting scaffolds. The proposed wireless sensor network combines an end device and a coordinator to allow easy replacement of sensors as compared to a wired network. A wake-up timer algorithm is proposed to reduce the transmitting power during continuous wireless data communication in the wireless sensor network. Furthermore, a variant binary exponential backoff transmission algorithm for data loss avoidance is proposed. The variant binary exponential backoff algorithm reduces packet collisions during simultaneous access by increasing the randomizing moments at nodes attempting to access the wireless channels. The performance of three of the proposed modules - a cable sensor, a 315-MHz sensor, and a ZigBee sensor - is evaluated in terms of packet delivery ratio and the end-to-end delay of a ZigBee-based wireless sensor network. The experimental results show that the proposed variant binary exponential backoff transmission algorithm achieves a higher packet delivery ratio at the cost of higher delays. The average cost of the developed ZigBee-based wireless sensor network decreased by 24% compared with the cable sensor. The power consumption of ZigBee is approximately 53.75% of the 315-MHz sensor. The average current consumption is reduced by approximately 1.5 mA with the wake-up timer algorithm at the same sampling rate. © The Author(s) 2016
The improvements of power management for clustered type large scope wireless sensor networks2010
Fuente Aragón, PDL. (2010). The improvements of power management for clustered type large scope wireless sensor networks2010. http://hdl.handle.net/10251/10244.Archivo delegad
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