Proposition and validation of an original MAC layer with simultaneous medium accesses for low latency wireless control/command applications

Control/command processes require a transmission system with some characteristics like high reliability, low latency and strong guarantees on messages delivery. Concerning wire networks, field buses technologies like FIP offer this kind of service (periodic tasks, real time constraints...). Unfortunately, few wireless technologies can propose a communication system which respects such constraints. Indeed, wireless transmissions must deal with medium characteristics which make impossible the direct translation of mechanisms used with wire networks. The purpose of this paper is to present an original Medium Access Control (MAC) layer for a real time Low Power-Wireless Personal Area Network (LP-WPAN). The proposed MAC-layer has been validated by several complementary methods; in this paper, we focus on the specific Simultaneous Guaranteed Time Slot (SGTS) part

On the use of IEEE 802.15.4/ZigBee as federating communication protocols for Wireless Sensor Networks

Tese de mestrado. Redes e Serviços de Comunicação. Faculdade de Engenharia. Universidade do Porto, Instituto Superior de Engenharia. 200

Cross-layer Dynamic Admission Control for Cloud-based Multimedia Sensor Networks

Publisher copyright and source must be acknowledged with citation. Must link to publisher version with DOICloud-based communications system is now widely used in many application fields such as medicine, security, environment protection, etc. Its use is being extended to the most demanding services like multimedia delivery. However, there are a lot of constraints when cloud-based sensor networks use the standard IEEE 802.15.3 or IEEE 802.15.4 technologies. This paper proposes a channel characterization scheme combined to a cross-layer admission control in dynamic cloud-based multimedia sensor networks to share the network resources among any two nodes. The analysis shows the behavior of two nodes using different network access technologies and the channel effects for each technology. Moreover, the existence of optimal node arrival rates in order to improve the usage of dynamic admission control when network resources are used is also shown. An extensive simulation study was performed to evaluate and validate the efficiency of the proposed dynamic admission control for cloud-based multimedia sensor networks.This work has been supported in part by Instituto de Telecomunicacoes, Next Generation Networks and Applications Group (NetGNA), Portugal, and in part by National Funding from the Fundacao para a Ciencia e Tecnologia through the Pest-OE/EEI/LA0008/2011.Mendes, LDP.; Rodrigues, JJPC.; Lloret, J.; Sendra Compte, S. (2014). Cross-layer Dynamic Admission Control for Cloud-based Multimedia Sensor Networks. IEEE Systems Journal. 8(1):235-246. doi:10.1109/JSYST.2013.2260653S2352468

A simple method for guaranteed deadline of periodic messages in 802.15.4 cluster cells for automation control applications

International audienceWe propose the implementation of a wireless sensor network applied to automation control applications, when the guarantee of a delay delivery for the complete reception of messages is necessary. The 802.15.4 wireless standard network offers possibilities of management of the bandwidth. This paper presents the method to guarantee the deadline transmission of periodic messages. For external messages (crossing the network from clusters to its destination), this average latency is used as a parameter of the routing protocol decision balance between energy saving and delay transmission. In this last case, a QoS method all over the network has to be installed to maintain a bounded end to end transmission delay. This work is still in progress. A specific Matlab simulator has been developed, principles of this routing method are mentioned at the end of this paper

Prototyping and Performance Analysis of a QoS MAC Layer for Industrial Wireless Network

Today's industrial sensor networks require strong reliability and guarantees on messages delivery. These needs are even more important in real time applications like control/command, such as robotic wireless communications where strong temporal constraints are critical. For these reasons, classical random-based Medium Access Control (MAC) protocols present a non-null frame collision probability. In this paper we present an original full deterministic MAC-layer for industrial wireless network and its performance evaluation thanks to the development of a material prototype.Comment: 7th IFAC International Conference on. Fieldbuses and nETworks in industrial and embedded systems, Toulouse : France (2007

Wireless Sensor Networks

The aim of this book is to present few important issues of WSNs, from the application, design and technology points of view. The book highlights power efficient design issues related to wireless sensor networks, the existing WSN applications, and discusses the research efforts being undertaken in this field which put the reader in good pace to be able to understand more advanced research and make a contribution in this field for themselves. It is believed that this book serves as a comprehensive reference for graduate and undergraduate senior students who seek to learn latest development in wireless sensor networks

MAC protocols for low-latency and energy-efficient WSN applications

Most of medium access control (MAC) protocols proposed for wireless sensor networks (WSN) are targeted only for single main objective, the energy efficiency. Other critical parameters such as low-latency, adaptivity to traffic conditions, scalability, system fairness, and bandwidth utilization are mostly overleaped or dealt as secondary objectives. The demand to address those issues increases with the growing interest in cheap, low-power, low- distance, and embedded WSNs. In this report, along with other vital parameters, we discuss suitability and limitations of different WSN MAC protocols for time critical and energy-efficient applications. As an example, we discuss the working of IEEE 802.15.4 in detail, explore its limitations, and derive efficient application-specific network parameter settings for time, energy, and bandwidth critical applications. Eventually, a new WSN MAC protocol Asynchronous Real-time Energy-efficient and Adaptive MAC (AREA-MAC) is proposed, which is intended to deal efficiently with time critical applications, and at the same time, to provide a better trade-off between other vital parameters, such as energy-efficiency, system fairness, throughput, scalability, and adaptivity to traffic conditions. On the other hand, two different optimization problems have been formulated using application-based traffic generating scenario to minimize network latency and maximize its lifetime

Does the assumption of exponential arrival distributions in wireless sensor networks hold?

Wireless Sensor Networks have seen a tremendous growth in various application areas despite prominent performance and availability challenges. One of the common configurations to prolong the lifetime and deal with the path loss phenomena having a multi-hop set-up with clusters and cluster heads to relay the information. Although researchers continue to address these challenges, the type of distribution for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. The general practice in published works is to compare an empirical exponential arrival distribution of wireless sensor networks with a theoretical exponential distribution in a Q-Q plot diagram. In this paper, we show that such comparisons based on simple eye checks are not sufficient since, in many cases, incorrect conclusions may be drawn from such plots. After estimating the Maximum Likelihood parameters of empirical distributions, we generate theoretical distributions based on the estimated parameters. By conducting Kolmogorov-Smirnov Test Statistics for each generated inter-arrival time distributions, we find out, if it is possible to represent the traffic into the cluster head by using theoretical distribution. Empirical exponential arrival distribution assumption of wireless sensor networks holds only for a few cases. There are both theoretically known such as Gamma, Log-normal and Mixed Log-Normal of arrival distributions and theoretically unknown such as non-Exponential and Mixed cases of arrival in wireless sensor networks. The work is further extended to understand the effect of delay on inter-arrival time distributions based on the type of medium access control used in wireless sensor networks

Does the assumption of exponential arrival distributions in wireless sensor networks hold?

Wireless Sensor Networks have seen a tremendous growth in various application areas despite prominent performance and availability challenges. One of the common configurations to prolong the lifetime and deal with the path loss phenomena having a multi-hop set-up with clusters and cluster heads to relay the information. Although researchers continue to address these challenges, the type of distribution for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. The general practice in published works is to compare an empirical exponential arrival distribution of wireless sensor networks with a theoretical exponential distribution in a Q-Q plot diagram. In this paper, we show that such comparisons based on simple eye checks are not sufficient since, in many cases, incorrect conclusions may be drawn from such plots. After estimating the Maximum Likelihood parameters of empirical distributions, we generate theoretical distributions based on the estimated parameters. By conducting Kolmogorov-Smirnov Test Statistics for each generated inter-arrival time distributions, we find out, if it is possible to represent the traffic into the cluster head by using theoretical distribution. Empirical exponential arrival distribution assumption of wireless sensor networks holds only for a few cases. There are both theoretically known such as Gamma, Log-normal and Mixed Log-Normal of arrival distributions and theoretically unknown such as non-Exponential and Mixed cases of arrival in wireless sensor networks. The work is further extended to understand the effect of delay on inter-arrival time distributions based on the type of medium access control used in wireless sensor networks

Routing and Mobility on IPv6 over LoWPAN

The IoT means a world-wide network of interconnected objects based on standard communication protocols. An object in this context is a quotidian physical device augmented with sensing/actuating, processing, storing and communication capabilities. These objects must be able to interact with the surrounding environment where they are placed and to cooperate with neighbouring objects in order to accomplish a common objective. The IoT objects have also the capabilities of converting the sensed data into automated instructions and communicating them to other objects through the communication networks, avoiding the human intervention in several tasks. Most of IoT deployments are based on small devices with restricted computational resources and energy constraints. For this reason, initially the scientific community did not consider the use of IP protocol suite in this scenarios because there was the perception that it was too heavy to the available resources on such devices. Meanwhile, the scientific community and the industry started to rethink about the use of IP protocol suite in all IoT devices and now it is considered as the solution to provide connectivity between the IoT devices, independently of the Layer 2 protocol in use, and to connect them to the Internet. Despite the use of IP suite protocol in all devices and the amount of solutions proposed, many open issues remain unsolved in order to reach a seamless integration between the IoT and the Internet and to provide the conditions to IoT service widespread. This thesis addressed the challenges associated with the interconnectivity between the Internet and the IoT devices and with the security aspects of the IoT. In the interconnectivity between the IoT devices and the Internet the problem is how to provide valuable information to the Internet connected devices, independently of the supported IP protocol version, without being necessary accessed directly to the IoT nodes. In order to solve this problem, solutions based on Representational state transfer (REST) web services and IPv4 to IPv6 dual stack transition mechanism were proposed and evaluated. The REST web service and the transition mechanism runs only at the border router without penalizing the IoT constrained devices. The mitigation of the effects of internal and external security attacks minimizing the overhead imposed on the IoT devices is the security challenge addressed in this thesis. Three different solutions were proposed. The first is a mechanism to prevent remotely initiated transport level Denial of Service attacks that avoids the use of inefficient and hard to manage traditional firewalls. It is based on filtering at the border router the traffic received from the Internet and destined to the IoT network according to the conditions announced by each IoT device. The second is a network access security framework that can be used to control the nodes that have access to the network, based on administrative approval, and to enforce security compliance to the authorized nodes. The third is a network admission control framework that prevents IoT unauthorized nodes to communicate with IoT authorized nodes or with the Internet, which drastically reduces the number of possible security attacks. The network admission control was also exploited as a management mechanism as it can be used to manage the network size in terms of number of nodes, making the network more manageable, increasing its reliability and extending its lifetime.A IoT (Internet of Things) tem suscitado o interesse tanto da comunidade académica como da indústria, uma vez que os campos de aplicação são inúmeros assim como os potenciais ganhos que podem ser obtidos através do uso deste tipo de tecnologia. A IoT significa uma rede global de objetos ligados entre si através de uma rede de comunicações baseada em protocolos standard. Neste contexto, um objeto é um objeto físico do dia a dia ao qual foi adicionada a capacidade de medir e de atuar sobre variáveis físicas, de processar e armazenar dados e de comunicar. Estes objetos têm a capacidade de interagir com o meio ambiente envolvente e de cooperar com outros objetos vizinhos de forma a atingirem um objetivo comum. Estes objetos também têm a capacidade de converter os dados lidos em instruções e de as comunicar a outros objetos através da rede de comunicações, evitando desta forma a intervenção humana em diversas tarefas. A maior parte das concretizações de sistemas IoT são baseados em pequenos dispositivos autónomos com restrições ao nível dos recursos computacionais e de retenção de energia. Por esta razão, inicialmente a comunidade científica não considerou adequado o uso da pilha protocolar IP neste tipo de dispositivos, uma vez que havia a perceção de que era muito pesada para os recursos computacionais disponíveis. Entretanto, a comunidade científica e a indústria retomaram a discussão acerca dos benefícios do uso da pilha protocolar em todos os dispositivos da IoT e atualmente é considerada a solução para estabelecer a conetividade entre os dispositivos IoT independentemente do protocolo da camada dois em uso e para os ligar à Internet. Apesar do uso da pilha protocolar IP em todos os dispositivos e da quantidade de soluções propostas, são vários os problemas por resolver no que concerne à integração contínua e sem interrupções da IoT na Internet e de criar as condições para a adoção generalizada deste tipo de tecnologias. Esta tese versa sobre os desafios associados à integração da IoT na Internet e dos aspetos de segurança da IoT. Relativamente à integração da IoT na Internet o problema é como fornecer informação válida aos dispositivos ligados à Internet, independentemente da versão do protocolo IP em uso, evitando o acesso direto aos dispositivos IoT. Para a resolução deste problema foram propostas e avaliadas soluções baseadas em web services REST e em mecanismos de transição IPv4 para IPv6 do tipo pilha dupla (dual stack). O web service e o mecanismo de transição são suportados apenas no router de fronteira, sem penalizar os dispositivos IoT. No que concerne à segurança, o problema é mitigar os efeitos dos ataques de segurança internos e externos iniciados local e remotamente. Foram propostas três soluções diferentes, a primeira é um mecanismo que minimiza os efeitos dos ataques de negação de serviço com origem na Internet e que evita o uso de mecanismos de firewalls ineficientes e de gestão complexa. Este mecanismo filtra no router de fronteira o tráfego com origem na Internet é destinado à IoT de acordo com as condições anunciadas por cada um dos dispositivos IoT da rede. A segunda solução, é uma framework de network admission control que controla quais os dispositivos que podem aceder à rede com base na autorização administrativa e que aplica políticas de conformidade relativas à segurança aos dispositivos autorizados. A terceira é um mecanismo de network admission control para redes 6LoWPAN que evita que dispositivos não autorizados comuniquem com outros dispositivos legítimos e com a Internet o que reduz drasticamente o número de ataques à segurança. Este mecanismo também foi explorado como um mecanismo de gestão uma vez que pode ser utilizado a dimensão da rede quanto ao número de dispositivos, tornando-a mais fácil de gerir e aumentando a sua fiabilidade e o seu tempo de vida