On the use of the ZigBee protocol for wireless sensor networks

This project was developed within the ART-WiSe framework of the IPP-HURRAY group (http://www.hurray.isep.ipp.pt), at the Polytechnic Institute of Porto (http://www.ipp.pt). The ART-WiSe – Architecture for Real-Time communications in Wireless Sensor networks – framework (http://www.hurray.isep.ipp.pt/art-wise) aims at providing new communication architectures and mechanisms to improve the timing performance of Wireless Sensor Networks (WSNs). The architecture is based on a two-tiered protocol structure, relying on existing standard communication protocols, namely IEEE 802.15.4 (Physical and Data Link Layers) and ZigBee (Network and Application Layers) for Tier 1 and IEEE 802.11 for Tier 2, which serves as a high-speed backbone for Tier 1 without energy consumption restrictions. Within this trend, an application test-bed is being developed with the objectives of implementing, assessing and validating the ART-WiSe architecture. Particularly for the ZigBee protocol case; even though there is a strong commercial lobby from the ZigBee Alliance (http://www.zigbee.org), there is neither an open source available to the community for this moment nor publications on its adequateness for larger-scale WSN applications. This project aims at fulfilling these gaps by providing: a deep analysis of the ZigBee Specification, mainly addressing the Network Layer and particularly its routing mechanisms; an identification of the ambiguities and open issues existent in the ZigBee protocol standard; the proposal of solutions to the previously referred problems; an implementation of a subset of the ZigBee Network Layer, namely the association procedure and the tree routing on our technological platform (MICAz motes, TinyOS operating system and nesC programming language) and an experimental evaluation of that routing mechanism for WSNs.

A survey of wireless technologies coexistence in WBAN: analysis and open research issues

Wireless Body Area Network (WBAN) is the most convenient, cost-effective, accurate, and non-invasive technology for e-health monitoring. The performance of WBAN may be disturbed when coexisting with other wireless networks. Accordingly, this paper provides a comprehensive study and in-depth analysis of coexistence issues and interference mitigation solutions in WBAN technologies. A thorough survey of state-of-the art research in WBAN coexistence issues is conducted. The survey classified, discussed, and compared the studies according to the parameters used to analyze the coexistence problem. Solutions suggested by the studies are then classified according to the followed techniques and concomitant shortcomings are identified. Moreover, the coexistence problem in WBAN technologies is mathematically analyzed and formulas are derived for the probability of successful channel access for different wireless technologies with the coexistence of an interfering network. Finally, extensive simulations are conducted using OPNET with several real-life scenarios to evaluate the impact of coexistence interference on different WBAN technologies. In particular, three main WBAN wireless technologies are considered: IEEE 802.15.6, IEEE 802.15.4, and low-power WiFi. The mathematical analysis and the simulation results are discussed and the impact of interfering network on the different wireless technologies is compared and analyzed. The results show that an interfering network (e.g., standard WiFi) has an impact on the performance of WBAN and may disrupt its operation. In addition, using low-power WiFi for WBANs is investigated and proved to be a feasible option compared to other wireless technologies.

Dynamic cluster scheduling for cluster-tree WSNs

While Cluster-Tree network topologies look promising for WSN applications with timeliness and energy-efficiency requirements, we are yet to witness its adoption in commercial and academic solutions. One of the arguments that hinder the use of these topologies concerns the lack of flexibility in adapting to changes in the network, such as in traffic flows. This paper presents a solution to enable these networks with the ability to self-adapt their clusters’ duty-cycle and scheduling, to provide increased quality of service to multiple traffic flows. Importantly, our approach enables a network to change its cluster scheduling without requiring long inaccessibility times or the re-association of the nodes. We show how to apply our methodology to the case of IEEE 802.15.4/ZigBee cluster-tree WSNs without significant changes to the protocol. Finally, we analyze and demonstrate the validity of our methodology through a comprehensive simulation and experimental validation using commercially available technology on a Structural Health Monitoring application scenario.

Espaços seguros de tuplos partilhados para redes de sensores sem fios

Dissertação para obtenção do Grau de Mestre em Engenharia Informática

Aplicação de Internet of Things em casas inteligentes: Serviços de Rede

O foco principal no estudo da Internet of Things tem sido a integração de dispositivos digitais com o mundo físico e vice-versa. Os dispositivos inteligentes têm vindo a ganhar uma forte presença na nossa vida diária e cada vez mais, tendem a integrar o sistema de uma casa, automatizando processos comuns como o controlo de temperatura ambiente ou mesmo a percentagem de luminosidade de uma divisão. A visão da IoT contempla um mundo interconectado, recolhendo informações de forma automática e possibilitando a comunicação entre dispositivos. Contudo, as tecnologias existentes para a criação de redes que albergam estes novos dispositivos carecem de padrões bem definidos, dificultando a interoperabilidade entre as diversas soluções existentes. Neste projeto são estudadas e aplicadas as tecnologias mais promissoras aplicáveis ao paradigma Internet of Things, com o objetivo de encontrar um conjunto de protocolos padrão para a implementação de sistemas de automação em casas inteligentes.1 Como objetivo final deste projeto, pretende-se criar uma rede de dispositivos com capacidades sensoriais que tenham a capacidade de comunicar com o mundo externo, permitindo o acesso à rede por qualquer tipo de utilizador. Com isso, espera-se caminhar para mais perto da padronização dos protocolos inerentes à IoT e habilitar interoperabilidade entre as mais diversas soluções. São apresentados e utilizados os protocolos que mais se adaptam ao tema escolhido, tentando simplificar a rede para que esta possa ser incluída em qualquer ambiente doméstico, recorrendo a hardware de custo reduzido. Os protocolos apresentados são o 6LoWPAN, utilizando o protocolo IEEE 802.15.4 como interface de rede juntamente com endereçamento IPv6. É também utilizado o protocolo CoAP na troca de mensagens entre os dispositivos.

Sensores “em movimento"

A domótica e a Internet das Coisas (Internet of Things – IoT) são dois conceitos que estão a ter bastante impacto na sociedade e a mudar o seu quotidiano, pelo que o utilizador é mais exigente na utilização dos seus equipamentos, pretendendo, que sejam mais simples e eficazes. A IoT é também muito utilizada na vertente da qualidade de vida (verificação da qualidade do ar, temperatura etc.) pelo que é necessário a utilização de uma rede de sensores de forma que toda a informação recolhida seja disponibilizada ao utilizador. Os sensores estão ligados a nós da rede de forma a recolherem informação. Essa rede pode ser constituída por diferentes topologias, sendo que a mais usual é a rede em Malha, pois no caso de um dos nós deixar de funcionar, a mensagem é enviada através de outros nós até chegar ao nó principal. O passo seguinte consiste em enviar toda essa informação para a Cloud, sendo que, nas soluções existentes, é necessário que o utilizador tenha um ponto fixo (gateway) com acesso à internet. Quando não é possível internet por cabo, a solução é a utilização de redes sem fios ou a utilização de, por exemplo, um cartão 3G/4G que implica o pagamento de taxas às operadoras móveis. Estas soluções implicam, na sua grande maioria uma instalação elétrica para alimentação dos nós dos sensores. O grande problema surge quando o utilizador não possui nenhum acesso à Internet (no local onde são instalados os sensores), ou no caso de não existência de nenhuma instalação elétrica para alimentação dos nós dos sensores. A solução proposta nesta dissertação consiste na utilização de um telemóvel, de um utilizador aleatório, como gateway. Assim, um utilizador comum pode ligar os seus sensores onde for necessário. Esses sensores são configurados Over-The-Air através de uma camada de aplicação do dispositivo de comunicação, como por exemplo, o Synapse. Após configuração, os sensores estão prontos a recolher toda a informação e enviá-la através da rede até ao nó principal. O nó principal é constituído pelo dispositivo de comunicação referido anteriormente, ligado a um microcontrolador (Arduino, por exemplo) que tem agregado um leitor de cartões SD e um dispositivo Bluetooth (BLE). Toda a informação recolhida pelos sensores é guardada no cartão SD até que um utilizador, com um telemóvel (Smartphone Android com a aplicação desenvolvida instalada) com o Bluetooth ligado, se aproxime do nó principal. Assim que a ligação é aceite e estabelecida, a aplicação envia a data mais recente de um sensor específico presente na sua base de dados na Cloud para o Arduino, permitindo que este apague os dados mais antigos presentes no cartão e envie, como resposta para o telemóvel, a informação mais antiga recolhida pelo sensor, atualizando assim a informação. A aplicação deste conceito pode ser útil quando não existe nenhuma ligação à internet ou quando um utilizador, por exemplo uma entidade responsável pelo meio ambiente e que seja necessário inserir sensores numa floresta, para prevenção de fogos. Assim os nós vão enviar toda a informação recolhida através da sua rede. Posteriormente, cabe ao utilizador escolher um sítio estratégico, onde saiba que irão passar indivíduos com alguma frequência, de modo a que estes recebam essa informação para o seu telemóvel.

Estudi i atac a les xarxes ZigBee

L'objectiu d'aquest article és mostrar les característiques essencials de dos protocols de xarxes de sensors -l'estàndard 802.15.4 i el protocol ZigBee-, així com les principals amenaces a les que estan exposats. Finalment, mitjançant un cas real i, com a prova de concepte, es mostra com deixar inhabilitat un node d'una xarxa que utilitza el protocol ZigBee.

ZigBee-verkot ja evaluointilaitteen suunnittelu

In this thesis a closer look at ZigBee wireless network protocol was made and a ZigBee evaluation device was designed and built for testing it. ZigBee is a digital wireless network technology published in 2004, which was developed for wireless control and automation systems. It is based on the IEEE 802.15.4-2003 standard, and its aim was to create a reliable wireless networking protocol with secure data transmissions, low power consumption and low manufacturing costs. The low power consumption requirement has also led to a slow data rate and a short range, but in a ZigBee network individual network devices can route messages to each other, so short range is not a problem. In automation and control systems a fast data rate is not usually an important requirement either. ZigBee network can form automatically and one ZigBee network can theoretically include thousands of devices, all of which can communicate with each other. ZigBee network is also self-healing, so an individual device dropping out of the network, like breaking down, does not affect functionality of the network. Evaluation device was designed and implemented in four different versions, which were tested with six different antenna designs. All antennas were tested at a range of 100 meters in an open terrain using two different frequencies and transmission powers. Also a range test was performed for selected antennas using transmission power of 4,5 dBm, which was maximum power of the ZigBee chip used in the evaluation device. Range test resulted in a measured range of several hundred meters, which can be considered as a good result for a short-range technology.

Implementation and Evaluation of an Improved Header Compression for 6LoWPAN

Extending IPv6 to IEEE 802.15.4-based Low power Wireless Personal Area Networks requires efficient header compression mechanisms to adapt to their limited bandwidth, memory and energy constraints. This paper presents an experimental evaluation of an improved header compression scheme which provides better compression of IPv6 multicast addresses and UDP port numbers compared to existing mechanisms. This scheme outperforms the existing compression mechanism in terms of data throughput of the network and energy consumption of nodes. It enhances throughput by up to 8% and reduces transmission energy of nodes by about 5%.

Zigbee för längre avstånd

I dag går utvecklingen av trådlösa nätverk snabbt framåt. Zigbee är en helt ny teknik som bygger på IEEE 802-15-4 standarden. Zigbee utvecklades av the Zigbee Alliance som består av en rad stora elektronikföretag. Zigbee är en teknik som inriktar sig på låg energiförbrukning och låg kostnad. Tekniken är tänkt att användas för att ställa in och läsa av sensorer av olika slag. Denna rapport är ett resultat av ett examensarbete som går ut på att utreda om Zigbee tekniken kan användas för lite längre avstånd. Arbetet resulterade i två demoapplikationer för ett enkel zigbee system, och färdigskriven kod för en möjlighet att använda Zigbee för länge avstånd.

Desenvolvimento de sistemas embarcados para redes de sensores e atuadores sem fio aplicadas em unidades de elevação de petróleo do tipo Plunger-Lift

The Wireless Sensor Networks (WSN) methods applied to the lifting of oil present as an area with growing demand technical and scientific in view of the optimizations that can be carried forward with existing processes. This dissertation has as main objective to present the development of embedded systems dedicated to a wireless sensor network based on IEEE 802.15.4, which applies the ZigBee protocol, between sensors, actuators and the PLC (Programmable Logic Controller), aiming to solve the present problems in the deployment and maintenance of the physical communication of current elevation oil units based on the method Plunger-Lift. Embedded systems developed for this application will be responsible for acquiring information from sensors and control actuators of the devices present at the well, and also, using the Modbus protocol to make this network becomes transparent to the PLC responsible for controlling the production and delivery information for supervisory SISAL

Desenvolvimento de um software de comunicação sem fio aplicado à instrumentação de unidade de elevação de petróleo tipo Plunger Lift

This dissertation aims to develop a software applied to a communication system for a wireless sensor network (WSN) for tracking analog and digital variables and control valve of the gas flow in artificial oil s elevation units, Plunger Lift type. The reason for this implementation is due to the fact that, in the studied plant configuration, the sensors communicate with the PLC (Programmable and Logic Controller) by the cables and pipelines, making any changes in that system, such as changing the layout of it, as well as inconveniences that arise from the nature of the site, such as the vicinity s animals presence that tend to destroy the cables for interconnection of sensors to the PLC. For software development, was used communication polling method via SMAC protocol (Simple Medium Access ControlIEEE 802.15.4 standard) in the CodeWarrior environment to which generated a firmware, loaded into the WSN s transceivers, present in the kit MC13193-EVK, (all items described above are owners of Freescale Semiconductors Inc.). The network monitoring and parameterization used in its application, was developed in LabVIEW software from National Instruments. The results were obtained through the observation of the network s behavior of sensors proposal, focusing on aspects such as: indoor and outdoor quantity of packages received and lost, general aspects of reliability in data transmission, coexistence with other types of wireless networks and power consumption under different operating conditions. The results were considered satisfactory, which showed the software efficiency in this communication system

Otimização de Algoritmos Criptográficos para Redes de Sensores e Atuadores Sem-fio para Poços do Tipo Plunger Lift

Wireless sensors and actuators Networks specified by IEEE 802.15.4, are becoming increasingly being applied to instrumentation, as in instrumentation of oil wells with completion Plunger Lift type. Due to specific characteristics of the environment being installed, it s find the risk of compromising network security, and presenting several attack scenarios and the potential damage from them. It`s found the need for a more detailed security study of these networks, which calls for use of encryption algorithms, like AES-128 bits and RC6. So then it was implement the algorithms RC6 and AES-128, in an 8 bits microcontroller, and study its performance characteristics, critical for embedded applications. From these results it was developed a Hybrid Algorithm Cryptographic, ACH, which showed intermediate characteristics between the AES and RC6, more appropriate for use in applications with limitations of power consumption and memory. Also was present a comparative study of quality of security among the three algorithms, proving ACH cryptographic capability.

Estudo e especificação de um sistema de instrumentação para unidades de elevação de petróleo utilizando tecnologia sem fio

Wireless sensor networks are reality nowadays. The growing necessity of connectivity between existing industrial plant equipments pushes the research and development of several technologies. The IEEE 802.15.4 LR-WPAN comes as a low-cost and powersaving viable solution, which are important concerns while making decisions on remote sensoring projects. This study intends to propose a wireless communication system which makes possible the monitoring of analogic and/or digital variables (i. e., the pressure studied) involved on the artificial methods for oil and gas lifting. The main issues are: To develop a software based on SMAC Standard in order to create a wireless network to monitoring analogic and/or digital variables; To evaluate the communication link based on the number of lost packets tested in different environments (indoor and outdoor) and To propose an instrumentation system consisting of wireless devices

Development of heterogeneous node network using microcontroller with protocols CAN and Zigbee

In this paper was proposed the development of an heterogeneous system using the microcontroller (AT90CANI28) where the protocol model CAN and the standard IEEE 802.15.4 are connected. This module is able to manage and monitor sensors and actuators using CAN and, through the wireless standard 802.15.4, communicate with the other network modules. © 2011 IEEE.