3,549 research outputs found
Performance Comparison of Contention- and Schedule-based MAC Protocols in Urban Parking Sensor Networks
Network traffic model is a critical problem for urban applications, mainly
because of its diversity and node density. As wireless sensor network is highly
concerned with the development of smart cities, careful consideration to
traffic model helps choose appropriate protocols and adapt network parameters
to reach best performances on energy-latency tradeoffs. In this paper, we
compare the performance of two off-the-shelf medium access control protocols on
two different kinds of traffic models, and then evaluate their application-end
information delay and energy consumption while varying traffic parameters and
network density. From the simulation results, we highlight some limits induced
by network density and occurrence frequency of event-driven applications. When
it comes to realtime urban services, a protocol selection shall be taken into
account - even dynamically - with a special attention to energy-delay tradeoff.
To this end, we provide several insights on parking sensor networks.Comment: ACM International Workshop on Wireless and Mobile Technologies for
Smart Cities (WiMobCity) (2014
Quality-Aware Broadcasting Strategies for Position Estimation in VANETs
The dissemination of vehicle position data all over the network is a
fundamental task in Vehicular Ad Hoc Network (VANET) operations, as
applications often need to know the position of other vehicles over a large
area. In such cases, inter-vehicular communications should be exploited to
satisfy application requirements, although congestion control mechanisms are
required to minimize the packet collision probability. In this work, we face
the issue of achieving accurate vehicle position estimation and prediction in a
VANET scenario. State of the art solutions to the problem try to broadcast the
positioning information periodically, so that vehicles can ensure that the
information their neighbors have about them is never older than the
inter-transmission period. However, the rate of decay of the information is not
deterministic in complex urban scenarios: the movements and maneuvers of
vehicles can often be erratic and unpredictable, making old positioning
information inaccurate or downright misleading. To address this problem, we
propose to use the Quality of Information (QoI) as the decision factor for
broadcasting. We implement a threshold-based strategy to distribute position
information whenever the positioning error passes a reference value, thereby
shifting the objective of the network to limiting the actual positioning error
and guaranteeing quality across the VANET. The threshold-based strategy can
reduce the network load by avoiding the transmission of redundant messages, as
well as improving the overall positioning accuracy by more than 20% in
realistic urban scenarios.Comment: 8 pages, 7 figures, 2 tables, accepted for presentation at European
Wireless 201
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Context-awareness for mobile sensing: a survey and future directions
The evolution of smartphones together with increasing computational power have empowered developers to create innovative context-aware applications for recognizing user related social and cognitive activities in any situation and at any location. The existence and awareness of the context provides the capability of being conscious of physical environments or situations around mobile device users. This allows network services to respond proactively and intelligently based on such awareness. The key idea behind context-aware applications is to encourage users to collect, analyze and share local sensory knowledge in the purpose for a large scale community use by creating a smart network. The desired network is capable of making autonomous logical decisions to actuate environmental objects, and also assist individuals. However, many open challenges remain, which are mostly arisen due to the middleware services provided in mobile devices have limited resources in terms of power, memory and bandwidth. Thus, it becomes critically important to study how the drawbacks can be elaborated and resolved, and at the same time better understand the opportunities for the research community to contribute to the context-awareness. To this end, this paper surveys the literature over the period of 1991-2014 from the emerging concepts to applications of context-awareness in mobile platforms by providing up-to-date research and future research directions. Moreover, it points out the challenges faced in this regard and enlighten them by proposing possible solutions
Dissemination of contextual information for assisted driving
Mestrado em Engenharia Electrónica e TelecomunicaçõesDriver assistance systems can be used to improve road and car safety, reduce
driving fatigue and provide a more e cient driving experience. An
important part of these systems is the communication between vehicles,
and vehicle-to-infrastructure communication. This work presents mechanisms
enabling driving support, exploring the vehicular network to provide
information about the drivers neighborhood.
The network is composed by vehicles, tra c signals and xed stations along
the road. Each car is equipped with a recording camera, a GPS receiver, as
well as communication modules such as WiFi, WAVE and 3G/4G, allowing
the exchange of data between the various nodes. The data exchanged is
composed by positional data of neighboring vehicles, sensor information
from tra c signals and video images incoming from other vehicles. This
data is used to facilitate the driver in decision making, but can also provide
an overview of the tra c density in the neighborhood. The tra c signals
broadcast their position and if they are dynamic (such as tra c lights), their
status is also transmitted. The xed stations are equipped with numerous
sensors and are used to provide environmental data.
The driver can access all the collected data via visual information, on a
display screen that contains a map of the neighborhood along with the
information available of the nearby nodes.
The proposed system is evaluated through real vehicular experiments in two
distinct scenarios: urban and highway. The results show that the communication
delay is higher in the highway scenario, mainly due to the distance
between vehicles and travelling speeds. However, promising results regarding
the maximum delay and the average number of retransmissions foresee
important inputs for future services of assisted-driving, in general, and carovertaking
assistance, in particular.Os sistemas de condução assistida podem ser utilizados para melhorar a
segurança rodoviária e automóvel, reduzir a fadiga da condução e proporcionar
uma experiência de condução mais e ciente. Uma parte importante
desses sistemas e a comunicação entre veĂculos e comunicação veiculo infraestrutura.
Este trabalho propõe mecanismos que permitem o suporte
a condução, explorando a rede de veicular para fornecer informações sobre
a vizinhança do condutor.
A rede e composta por veĂculos, sinais de transito e estações fixas ao longo
da estrada. Cada carro esta equipado com uma camera de gravação, um
receptor GPS, bem como módulos de comunicação, como WiFi, WAVE e
3G/4G, permitindo a troca de dados entre os vários nos. Os dados trocados
sĂŁo compostos por dados posicionais de veĂculos vizinhos, informações
sensoriais de sinais de trânsito e imagens de vĂdeo provenientes de outros
veĂculos. Esses dados s~ao usados para facilitar a tomada de decisões, mas
também podem fornecer uma vis~ao geral da densidade de tráfego na vizinhança. Os sinais de transito transmitem a sua posição e, no caso de serem dinâmicos (como semáforos), o seu estado actual também e transmitido.
As estações fixas estão equipadas com vários sensores e sao usadas para
fornecer dados ambientais.
O condutor pode aceder a todos os dados recolhidos através de informações
visuais, num ecrã que contém um mapa da sua redondeza junto com a
informação disponĂvel dos nos vizinhos.
O sistema proposto e avaliado através de testes reais em dois cenários
distintos: urbano e auto-estrada. Os resultados mostram que o atraso da
comunicação e maior no cenário da auto-estrada, principalmente devido as
maiores distancias entre os veĂculos e as velocidades mais elevadas. No
entanto, resultados promissores em relação ao atraso máximo e ao numero
médio de retransmissões prevêem contribuições importantes para serviços
futuros de condução assistida em geral, e assistência de ultrapassagem de
veĂculos, em particular
Towards video streaming in IoT environments: vehicular communication perspective
Multimedia oriented Internet of Things (IoT) enables pervasive and real-time communication of video, audio and image data among devices in an immediate surroundings. Today's vehicles have the capability of supporting real time multimedia acquisition. Vehicles with high illuminating infrared cameras and customized sensors can communicate with other on-road devices using dedicated short-range communication (DSRC) and 5G enabled communication technologies. Real time incidence of both urban and highway vehicular traffic environment can be captured and transmitted using vehicle-to-vehicle and vehicle-to-infrastructure communication modes. Video streaming in vehicular IoT (VSV-IoT) environments is in growing stage with several challenges that need to be addressed ranging from limited resources in IoT devices, intermittent connection in vehicular networks, heterogeneous devices, dynamism and scalability in video encoding, bandwidth underutilization in video delivery, and attaining application-precise quality of service in video streaming. In this context, this paper presents a comprehensive review on video streaming in IoT environments focusing on vehicular communication perspective. Specifically, significance of video streaming in vehicular IoT environments is highlighted focusing on integration of vehicular communication with 5G enabled IoT technologies, and smart city oriented application areas for VSV-IoT. A taxonomy is presented for the classification of related literature on video streaming in vehicular network environments. Following the taxonomy, critical review of literature is performed focusing on major functional model, strengths and weaknesses. Metrics for video streaming in vehicular IoT environments are derived and comparatively analyzed in terms of their usage and evaluation capabilities. Open research challenges in VSV-IoT are identified as future directions of research in the area. The survey would benefit both IoT and vehicle industry practitioners and researchers, in terms of augmenting understanding of vehicular video streaming and its IoT related trends and issues
Thirty Years of Machine Learning: The Road to Pareto-Optimal Wireless Networks
Future wireless networks have a substantial potential in terms of supporting
a broad range of complex compelling applications both in military and civilian
fields, where the users are able to enjoy high-rate, low-latency, low-cost and
reliable information services. Achieving this ambitious goal requires new radio
techniques for adaptive learning and intelligent decision making because of the
complex heterogeneous nature of the network structures and wireless services.
Machine learning (ML) algorithms have great success in supporting big data
analytics, efficient parameter estimation and interactive decision making.
Hence, in this article, we review the thirty-year history of ML by elaborating
on supervised learning, unsupervised learning, reinforcement learning and deep
learning. Furthermore, we investigate their employment in the compelling
applications of wireless networks, including heterogeneous networks (HetNets),
cognitive radios (CR), Internet of things (IoT), machine to machine networks
(M2M), and so on. This article aims for assisting the readers in clarifying the
motivation and methodology of the various ML algorithms, so as to invoke them
for hitherto unexplored services as well as scenarios of future wireless
networks.Comment: 46 pages, 22 fig
An Effective Wireless Sensor Network Routing Protocol Based on Particle Swarm Optimization Algorithm
Improving wireless communication and artificial intelligence technologies by using Internet of Things (Itoh) paradigm has been contributed in developing a wide range of different applications. However, the exponential growth of smart phones and Internet of Things (IoT) devices in wireless sensor networks (WSNs) is becoming an emerging challenge that adds some limitations on Quality of Service (QoS) requirements. End-to-end latency, energy consumption, and packet loss during transmission are the main QoS requirements that could be affected by increasing the number of IoT applications connected through WSNs. To address these limitations, an effective routing protocol needs to be designed for boosting the performance of WSNs and QoS metrics. In this paper, an optimization approach using Particle Swarm Optimization (PSO) algorithm is proposed to develop a multipath protocol, called a Particle Swarm Optimization Routing Protocol (MPSORP). The MPSORP is used for WSN-based IoT applications with a large volume of traffic loads and unfairness in network flow. For evaluating the developed protocol, an experiment is conducted using NS-2 simulator with different configurations and parameters. Furthermore, the performance of MPSORP is compared with AODV and DSDV routing protocols. The experimental results of this comparison demonstrated that the proposed approach achieves several advantages such as saving energy, low end-to-end delay, high packet delivery ratio, high throughput, and low normalization load.publishedVersio
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