460 research outputs found

    Adoption of vehicular ad hoc networking protocols by networked robots

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    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 Mini Review of Peer-to-Peer (P2P) for Vehicular Communication

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    In recent times, peer-to-peer (P2P) has evolved, where it leverages the capability to scale compared to server-based networks. Consequently, P2P has appeared to be the future distributed systems in emerging several applications. P2P is actually a disruptive technology for setting up applications that scale to numerous concurrent individuals. Thus, in a P2P distributed system, individuals become themselves as peers through contributing, sharing, and managing the resources in a network. In this paper, P2P for vehicular communication is explored. A comprehensive of the functioning concept of both P2P along with vehicular communication is examined. In addition, the advantages are furthermore conversed for a far better understanding on the implementation

    Emergency message dissemination schemes based on congestion avoidance in VANET and vehicular FoG computing

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    With the rapid growth in connected vehicles, FoG-assisted vehicular ad hoc network (VANET) is an emerging and novel field of research. For information sharing, a number of messages are exchanged in various applications, including traffic monitoring and area-specific live weather and social aspects monitoring. It is quite challenging where vehicles' speed, direction, and density of neighbors on the move are not consistent. In this scenario, congestion avoidance is also quite challenging to avoid communication loss during busy hours or in emergency cases. This paper presents emergency message dissemination schemes that are based on congestion avoidance scenario in VANET and vehicular FoG computing. In the similar vein, FoG-assisted VANET architecture is explored that can efficiently manage the message congestion scenarios. We present a taxonomy of schemes that address message congestion avoidance. Next, we have included a discussion about comparison of congestion avoidance schemes to highlight the strengths and weaknesses. We have also identified that FoG servers help to reduce the accessibility delays and congestion as compared to directly approaching cloud for all requests in linkage with big data repositories. For the dependable applicability of FoG in VANET, we have identified a number of open research challenges. © 2013 IEEE

    SCALABLE MULTI-HOP DATA DISSEMINATION IN VEHICULAR AD HOC NETWORKS

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    Vehicular Ad hoc Networks (VANETs) aim at improving road safety and travel comfort, by providing self-organizing environments to disseminate traffic data, without requiring fixed infrastructure or centralized administration. Since traffic data is of public interest and usually benefit a group of users rather than a specific individual, it is more appropriate to rely on broadcasting for data dissemination in VANETs. However, broadcasting under dense networks suffers from high percentage of data redundancy that wastes the limited radio channel bandwidth. Moreover, packet collisions may lead to the broadcast storm problem when large number of vehicles in the same vicinity rebroadcast nearly simultaneously. The broadcast storm problem is still challenging in the context of VANET, due to the rapid changes in the network topology, which are difficult to predict and manage. Existing solutions either do not scale well under high density scenarios, or require extra communication overhead to estimate traffic density, so as to manage data dissemination accordingly. In this dissertation, we specifically aim at providing an efficient solution for the broadcast storm problem in VANETs, in order to support different types of applications. A novel approach is developed to provide scalable broadcast without extra communication overhead, by relying on traffic regime estimation using speed data. We theoretically validate the utilization of speed instead of the density to estimate traffic flow. The results of simulating our approach under different density scenarios show its efficiency in providing scalable multi-hop data dissemination for VANETs

    Detecting Non-Line of Sight to Prevent Accidents in Vehicular Ad hoc Networks

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    There are still many challenges in the field of VANETs that encouraged researchers to conduct further investigation in this field to meet these challenges. The issue pertaining to routing protocols such as delivering the warning messages to the vehicles facing Non-Line of Sight (NLOS) situations without causing the storm problem and channel contention, is regarded as a serious dilemma which is required to be tackled in VANET, especially in congested environments. This requires the designing of an efficient mechanism of routing protocol that can broadcast the warning messages from the emergency vehicles to the vehicles under NLOS, reducing the overhead and increasing the packet delivery ratio with a reduced time delay and channel utilisation. The main aim of this work is to develop the novel routing protocol for a high-density environment in VANET through utilisation of its high mobility features, aid of the sensors such as Global Positioning System (GPS) and Navigation System (NS). In this work, the cooperative approach has been used to develop the routing protocol called the Co-operative Volunteer Protocol (CVP), which uses volunteer vehicles to disseminate the warning message from the source to the target vehicle under NLOS issue; this also increases the packet delivery ratio, detection of NLOS and resolution of NLOS by delivering the warning message successfully to the vehicle under NLOS, thereby causing a direct impact on the reduction of collisions between vehicles in normal mode and emergency mode on the road near intersections or on highways. The cooperative approach adopted for warning message dissemination reduced the rebroadcast rate of messages, thereby decreasing significantly the storm issue and the channel contention. A novel architecture has been developed by utilising the concept of a Context-Aware System (CAS), which clarifies the OBU components and their interaction with each other in order to collect data and take the decisions based on the sensed circumstances. The proposed architecture has been divided into three main phases: sensing, processing and acting. The results obtained from the validation of the proposed CVP protocol using the simulator EstiNet under specific conditions and parameters showed that performance of the proposed protocol is better than that of the GRANT protocol with regard to several metrics such as packet delivery ratio, neighbourhood awareness, channel utilisation, overhead and latency. It is also successfully shown that the proposed CVP could detect the NLOS situation and solves it effectively and efficiently for both the intersection scenario in urban areas and the highway scenario

    Comunicações confiáveis sem-fios para redes veiculares

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    Vehicular communications are a promising field of research, with numerous potential services that can enhance traffic experience. Road safety is the most important objective behind the development of wireless vehicular networks, since many of the current accidents and fatalities could be avoided if vehicles had the ability to share information among them, with the road-side infrastructure and other road users. A future with safe, efficient and comfortable road transportation systems is envisaged by the different traffic stakeholders - users, manufacturers, road operators and public authorities. Cooperative Intelligent Transportation Systems (ITS) applications will contribute to achieve this goal, as well as other technological progress, such as automated driving or improved road infrastructure based on advanced sensoring and the Internet of Things (IoT) paradigm. Despite these significant benefits, the design of vehicular communications systems poses difficult challenges, mainly due to the very dynamic environments in which they operate. In order to attain the safety-critical requirements involved in this type of scenarios, careful planning is necessary, so that a trustworthy behaviour of the system can be achieved. Dependability and real-time systems concepts provide essential tools to handle this challenging task of enabling determinism and fault-tolerance in vehicular networks. This thesis aims to address some of these issues by proposing architectures and implementing mechanisms that improve the dependability levels of realtime vehicular communications. The developed strategies always try to preserve the required system’s flexibity, a fundamental property in such unpredictable scenarios, where unexpected events may occur and force the system to quickly adapt to the new circumnstances.The core contribution of this thesis focuses on the design of a fault-tolerant architecture for infrastructure-based vehicular networks. It encompasses a set of mechanisms that allow error detection and fault-tolerant behaviour both in the mobile and static nodes of the network. Road-side infrastructure plays a key role in this context, since it provides the support for coordinating all communications taking place in the wireless medium. Furthermore, it is also responsible for admission control policies and exchanging information with the backbone network. The proposed methods rely on a deterministic medium access control (MAC) protocol that provides real-time guarantees in wireless channel access, ensuring that communications take place before a given deadline. However, the presented solutions are generic and can be easily adapted to other protocols and wireless technologies. Interference mitigation techniques, mechanisms to enforce fail-silent behaviour and redundancy schemes are introduced in this work, so that vehicular communications systems may present higher dependability levels. In addition to this, all of these methods are included in the design of vehicular network components, guaranteeing that the real-time constraints are still fulfilled. In conclusion, wireless vehicular networks hold the potential to drastically improve road safety. However, these systems should present dependable behaviour in order to reliably prevent the occurrence of catastrophic events under all possible traffic scenarios.As comunicações veiculares são uma área de investigação bastante promissora, com inúmeros potenciais serviços que podem melhorar a experiência vivida no tráfego. A segurança rodoviária é o objectivo mais importante por detrás do desenvolvimento das redes veiculares sem-fios, visto que muitos dos atuais acidentes e vítimas mortais poderiam ser evitados caso os veículos tivessem a capacidade de trocar informação entre eles, com a infraestrutura rodoviária e outros utilizadores da estrada. Um futuro com sistemas de transporte rodoviário seguros, eficientes e confortáveis é algo ambicionado pelas diferentes partes envolvidas - utilizadores, fabricantes, operadores da infraestrutura e autoridades públicas. As aplicações de Sistemas Inteligentes de Transporte (ITS) cooperativas vão contribuir para alcançar este propósito, em conjunto com outros avanços tecnológicos, nomeadamente a condução autónoma ou uma melhor infraestrutura rodoviária baseada em sensorização avançada e no paradigma da Internet das Coisas (IoT). Apesar destes benefícios significativos, o desenho de sistemas de comunicações veiculares coloca desafios difíceis, em grande parte devido aos ambientes extremamente dinâmicos em que estes operam. De modo a atingir os requisitos de segurança crítica envolvidos neste tipo de cenários, é necessário um cuidadoso planeamento por forma a que o sistema apresente um comportamento confiável. Conceitos de dependabilidade e de sistemas de tempo-real constituem ferramentas essenciais para lidar com esta desafiante tarefa de dotar as redes veiculares de determinismo e tolerância a faltas. Esta tese pretende endereçar alguns destes problemas através da proposta de arquitecturas e da implementação de mecanismos que melhorem os níveis da dependabilidade das comunicações veiculares de tempo-real. As estratégias desenvolvidas tentam sempre preservar a necessária flexibilidade do sistema, uma propriedade fundamental em cenários tão imprevisíveis, onde eventos inesperados podem ocorrer e forçar o sistema a adaptar-se rapidamente às novas circunstâncias.A contribuição principal desta tese foca-se no desenho de uma arquitectura tolerante a faltas para redes veiculares com suporte da infraestrutura de beira de estrada. Esta arquitectura engloba um conjunto de mecanismos que permite detecção de erros e comportamento tolerante a faltas, tanto nos nós móveis como nos nós estáticos da rede. A infraestrutura de beira de estrada desempenha um papel fundamental neste contexto, pois fornece o suporte que permite coordenar todas as comunicações que ocorrem no meio sem-fios. Para além disso, é também responsável pelos mecanismos de controlo de admissão e pela troca de informação com a rede de transporte. Os métodos propostos baseiam-se num protocolo determinístico de controlo de acesso ao meio (MAC) que fornece garantias de tempo-real no accesso ao canal semfios, assegurando que as comunicações ocorrem antes de um determinado limite temporal. No entanto, as soluções apresentadas são genéricas e podem ser facilmente adaptadas a outros protocolos e tecnologias sem-fios. Neste trabalho são introduzidas técnicas de mitigação de interferência, mecanismos para assegurar comportamento falha-silêncio e esquemas de redundância, de modo a que os sistemas de comunicações veiculares apresentem elevados níveis de dependabilidade. Além disso, todos estes métodos são incorporados no desenho dos componentes da rede veicular, guarantindo que as restrições de tempo-real continuam a ser cumpridas. Em suma, as redes veiculares sem-fios têm o potential para melhorar drasticamente a segurança rodoviária. Contudo, estes sistemas precisam de apresentar um comportamento confiável, de forma a prevenir a ocorrência de eventos catastróficos em todos os cenários de tráfego possíveis.Programa Doutoral em Telecomunicaçõe

    Collaborative, Intelligent, and Adaptive Systems for the Low-Power Internet of Things

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    With the emergence of the Internet of Things (IoT), more and more devices are getting equipped with communication capabilities, often via wireless radios. Their deployments pave the way for new and mission-critical applications: cars will communicate with nearby vehicles to coordinate at intersections; industrial wireless closed-loop systems will improve operational safety in factories; while swarms of drones will coordinate to plan collision-free trajectories. To achieve these goals, IoT devices will need to communicate, coordinate, and collaborate over the wireless medium. However, these envisioned applications necessitate new characteristics that current solutions and protocols cannot fulfill: IoT devices require consistency guarantees from their communication and demand for adaptive behavior in complex and dynamic environments.In this thesis, we design, implement, and evaluate systems and mechanisms to enable safe coordination and adaptivity for the smallest IoT devices. To ensure consistent coordination, we bring fault-tolerant consensus to low-power wireless communication and introduce Wireless Paxos, a flavor of the Paxos algorithm specifically tailored to low-power IoT. We then present STARC, a wireless coordination mechanism for intersection management combining commit semantics with synchronous transmissions. To enable adaptivity in the wireless networking stack, we introduce Dimmer and eAFH. Dimmer combines Reinforcement Learning and Multi-Armed Bandits to adapt its communication parameters and counteract the adverse effects of wireless interference at runtime while optimizing energy consumption in normal conditions. eAFH provides dynamic channel management in Bluetooth Low Energy by excluding and dynamically re-including channels in scenarios with mobility. Finally, we demonstrate with BlueSeer that a device can classify its environment, i.e., recognize whether it is located in a home, office, street, or transport, solely from received Bluetooth Low Energy signals fed into an embedded machine learning model. BlueSeer therefore increases the intelligence of the smallest IoT devices, allowing them to adapt their behaviors to their current surroundings

    Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks

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    This book presents collective works published in the recent Special Issue (SI) entitled "Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks”. These works expose the readership to the latest solutions and techniques for MANETs and VANETs. They cover interesting topics such as power-aware optimization solutions for MANETs, data dissemination in VANETs, adaptive multi-hop broadcast schemes for VANETs, multi-metric routing protocols for VANETs, and incentive mechanisms to encourage the distribution of information in VANETs. The book demonstrates pioneering work in these fields, investigates novel solutions and methods, and discusses future trends in these field
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