Supporting Preemptive Multitasking in Wireless Sensor Networks

Supporting the concurrent execution of multiple tasks on lightweight sensor nodes could enable the deployment of independent applications on a shared wireless sensor network, thus saving cost and time by exploiting infrastructures which are typically underutilized if dedicated to a single task. Existing approaches to wireless sensor network programming provide limited support to concurrency at the cost of reducing the generality and the expressiveness of the language adopted. This paper presents a java-compatible platform for wireless sensor networks which provides a thorough support to preemptive multitasking while allowing the programmers to write their applications in java. The proposed approach has been implemented and tested on top of VirtualSense, an ultra-low-power wireless sensor mote providing a java-compatible runtime environment. Performance and scalability of the solution are discussed in light of extensive experiments performed on representative benchmarks

Wireless Sensor Network for Aircraft Cabin Environment Sensing

Wireless sensor networks consist of physically distributed autonomous sensor nodes that cooperatively monitor physical or environmental conditions. One of the greatest benefits of wireless sensor networks is that they are capable of generating a more complete view of the sensed environment by acquiring larger quantities of correlated data than independent sensor monitors. The aircraft cabin is a highly dynamic environment which necessitates the use of more advanced sensing systems. It is with the motivation of painting a better picture of the aircraft cabin environment that such a wireless sensor network is being designed and prototyped. This paper discusses the design considerations required for wireless sensor networks in the aircraft cabin environment, as well as an overview of past and present systems developed for use in aircraft cabin environmental sensing. In addition to the sensor network, supporting tools are also discussed to enable analysis of the data collected. The primary goal of this research is to provide sensing tools to enable better characterization of the aircraft cabin environment

Hardware support for memory protection in sensor nodes

With reference to the typical hardware configuration of a sensor node, we present the architecture of a memory protection unit (MPU) designed as a low-complexity addition to the microcontroller. The MPU is aimed at supporting memory protection and the privileged execution mode. It is connected to the system buses, and is seen by the processor as a memory-mapped input/output device. The contents of the internal MPU registers specify the composition of the protection contexts of the running program in terms of access rights for the memory pages. The MPU generates a hardware interrupt to the processor when it detects a protection violation. The proposed MPU architecture is evaluated from a number of salient viewpoints, which include the distribution, review and revocation of access permissions, and the support for important memory protection paradigms, including hierarchical contexts and protection rings

Wireless Sensor Network Virtualization: A Survey

Wireless Sensor Networks (WSNs) are the key components of the emerging Internet-of-Things (IoT) paradigm. They are now ubiquitous and used in a plurality of application domains. WSNs are still domain specific and usually deployed to support a specific application. However, as WSN nodes are becoming more and more powerful, it is getting more and more pertinent to research how multiple applications could share a very same WSN infrastructure. Virtualization is a technology that can potentially enable this sharing. This paper is a survey on WSN virtualization. It provides a comprehensive review of the state-of-the-art and an in-depth discussion of the research issues. We introduce the basics of WSN virtualization and motivate its pertinence with carefully selected scenarios. Existing works are presented in detail and critically evaluated using a set of requirements derived from the scenarios. The pertinent research projects are also reviewed. Several research issues are also discussed with hints on how they could be tackled.Comment: Accepted for publication on 3rd March 2015 in forthcoming issue of IEEE Communication Surveys and Tutorials. This version has NOT been proof-read and may have some some inconsistencies. Please refer to final version published in IEEE Xplor

A Survey of Operating Systems Infrastructure for Embedded Systems

Since early applications in the 1960s, embedded systems have come down in price and there has been a dramatic rise in processing power and functionality. In addition, embedded systems are becoming increasingly complex. High-end devices, such as mobile phones, PDAs, entertainment devices, and set-top boxes, feature millions of lines of code with varying degrees of assurance of correctness. Nowadays, more and more embedded systems are implemented in a distributed way, a wide range of high-performance distributed embedded systems have been designed and deployed. As a lot of aspects of embedded system design become increasingly dependent on the effective interaction of distributed processors, it is clear that as much effort needs to be focused on software infrastructure, such as operating systems, with respect to how to provide functionality in order to fulfill these requirements. This technical report presents some of the approaches associated to operating systems that have been used in order to fulfill these needs.CAPES/MEC - Brasil, Project BEX3342/08-

Simulating Real-Time Aspects of Wireless Sensor Networks

Wireless Sensor Networks (WSNs) technology has been mainly used in the applications with low-frequency sampling and little computational complexity. Recently, new classes of WSN-based applications with different characteristics are being considered, including process control, industrial automation and visual surveillance. Such new applications usually involve relatively heavy computations and also present real-time requirements as bounded end-to- end delay and guaranteed Quality of Service. It becomes then necessary to employ proper resource management policies, not only for communication resources but also jointly for computing resources, in the design and development of such WSN-based applications. In this context, simulation can play a critical role, together with analytical models, for validating a system design against the parameters of Quality of Service demanded for. In this paper, we present RTNS, a publicly available free simulation tool which includes Operating System aspects in wireless distributed applications. RTNS extends the well-known NS-2 simulator with models of the CPU, the Real-Time Operating System and the application tasks, to take into account delays due to the computation in addition to the communication. We demonstrate the benefits of RTNS by presenting our simulation study for a complex WSN-based multi-view vision system for real-time event detection

Wireless Data Logger – A Joint Use of Frequency Converter and Wireless Sensor Network

“Smart Industry” is a new unavoidable trend in vast varieties of industry fields. In the case of developing smart crane systems, cutting edge innovation and design is required. Many crane manufactures have expressed their strong interest in applying wireless technology to their crane products. Recent research achievements in wireless sensor node development have created technologically mature, cost effective solutions for many applications. When either monitoring or controlling the crane, one must have access to the frequency converter first. As for the purpose of analyzing the behavior of crane, the Wireless Sensor Network can be used to collect data from frequency converters. In this thesis, a wireless sensor network system was designed and developed in order to collect data from several frequency converters. The UWASA Node, a wireless sensor node designed by researchers from Aalto University and University of Vaasa, was implemented for establishing this wireless data logging network. As a result, the system has an ability of logging continuous data as well as the changes of data in user defined logging interval. Additionally, the reliability of the wireless transmission was investigated and possible solutions were presented.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Protocolo de comunicações sem-fios em malha para redes de iluminação pública

Mestrado em Engenharia Eletrónica e TelecomunicaçõesThe digital revolution of the 21st century contributed to stem the Internet of Things (IoT). Trillions of embedded devices using the Internet Protocol (IP), also called smart objects, will be an integral part of the Internet. In order to support such an extremely large address space, a new Internet Protocol, called Internet Protocol Version 6 (IPv6) is being adopted. The IPv6 over Low Power Wireless Personal Area Networks (6LoWPAN) has accelerated the integration of WSNs into the Internet. At the same time, the Constrained Application Protocol (CoAP) has made it possible to provide resource constrained devices with RESTful Web services functionalities. This work builds upon previous experience in street lighting networks, for which a proprietary protocol, devised by the Lighting Living Lab, was implemented and used for several years. The proprietary protocol runs on a broad range of lighting control boards. In order to support heterogeneous applications with more demanding communication requirements and to improve the application development process, it was decided to port the Contiki OS to the four channel LED driver (4LD) board from Globaltronic. This thesis describes the work done to adapt the Contiki OS to support the Microchip TM PIC24FJ128GA308 microprocessor and presents an IP based solution to integrate sensors and actuators in smart lighting applications. Besides detailing the system’s architecture and implementation, this thesis presents multiple results showing that the performance of CoAP based resource retrievals in constrained nodes is adequate for supporting networking services in street lighting networks.A revolução digital do século 21 contribuiu para o surgimento da Internet das Coisas (IoT). Em breve triliões de dispositivos embutidos usando o Internet Protocol (IP) serão parte integrante da Internet. De modo a suportar tal gama de endereços, um novo protocolo de Internet, chamado Internet Protocol versão 6 (IPv6) está a ser adoptado. O IPv6 over Low power Wireless Personal Area Networks (6LoWPAN) acelerou a integração das redes sem-fios de sensores na Internet. Ao mesmo tempo, o Constrained Application Protocol (CoAP) tornou possível fornecer funcionalidades de serviços Web RESTful a dispositivos com recursos limitados. Este trabalho baseia-se em experiências anteriores em redes de iluminação pública, para os quais um protocolo proprietário, elaborado pelo Lighting Living Lab, foi implementado e usado durante vários anos. O protocolo proprietário tem sido utilizado numa ampla gama de placas de controlo de iluminação. De modo a suportar aplicações heterogéneas com requisitos de comunicação mais exigentes além de melhorar o processo de desenvolvimento de aplicações, adaptou-se o Contiki OS à placa LED driver de 4 canais (4LD) da Globaltronic. Esta dissertação descreve o trabalho conduzido para adaptar o Contiki OS ao microprocessador Microchip TM PIC24FJ128GA308 e apresenta uma solução baseada em IP para integrar sensores e atuadores em aplicações de iluminação inteligentes. Além da descrição da arquitetura e da implementação do sistema, este trabalho apresenta vários resultados que mostram que o desempenho do protocolo CoAP na placa 4LD é adequado para suportar serviços Web em redes de iluminação pública

Abstracting Application Development for Resource Constrained Wireless Sensor Networks

Ubiquitous computing is a concept whereby computing is distributed across smart objects surrounding users, creating ambient intelligence. Ubiquitous applications use technologies such as the Internet, sensors, actuators, embedded computers, wireless communication, and new user interfaces. The Internet-of-Things (IoT) is one of the key concepts in the realization of ubiquitous computing, whereby smart objects communicate with each other and the Internet. Further, Wireless Sensor Networks (WSNs) are a sub-group of IoT technologies that consist of geographically distributed devices or nodes, capable of sensing and actuating the environment.WSNs typically contain tens to thousands of nodes that organize and operate autonomously to perform application-dependent sensing and sensor data processing tasks. The projected applications require nodes to be small in physical size and low-cost, and have a long lifetime with limited energy resources, while performing complex computing and communications tasks. As a result, WSNs are complex distributed systems that are constrained by communications, computing and energy resources. WSN functionality is dynamic according to the environment and application requirements. Dynamic multitasking, task distribution, task injection, and software updates are required in field experiments for possibly thousands of nodes functioning in harsh environments.The development of WSN application software requires the abstraction of computing, communication, data access, and heterogeneous sensor data sources to reduce the complexities. Abstractions enable the faster development of new applications with a better reuse of existing software, as applications are composed of high-level tasks that use the services provided by the devices to execute the application logic.The main research question of this thesis is: What abstractions are needed for application development for resource constrained WSNs? This thesis models WSN abstractions with three levels that build on top of each other: 1) node abstraction, 2) network abstraction, and 3) infrastructure abstraction. The node abstraction hides the details in the use of the sensing, communication, and processing hardware. The network abstraction specifies methods of discovering and accessing services, and distributing processing in the network. The infrastructure abstraction unifies different sensing technologies and infrastructure computing platforms.As a contribution, this thesis presents the abstraction model with a review of each abstraction level. Several designs for each of the levels are tested and verified with proofs of concept and analyses of field experiments. The resulting designs consist of an operating system kernel, a software update method, a data unification interface, and all abstraction levels combining abstraction called an embedded cloud.The presented operating system kernel has a scalable overhead and provides a programming approach similar to a desktop computer operating system with threads and processes. An over-the-air update method combines low overhead and robust software updating with application task dissemination. The data unification interface homogenizes the access to the data of heterogeneous sensor networks. A unification model is used for various use cases by mapping everything as measurements. The embedded cloud allows resource constrained WSNs to share services and data, and expand resources with other technologies. The embedded cloud allows the distributed processing of applications according to the available services. The applications are implemented as processes using a hardware independent description language that can be executed on resource constrained WSNs. The lessons of practical field experimenting are analyzed to study the importance of the abstractions. Software complexities encountered in the field experiments highlight the need for suitable abstractions.The results of this thesis are tested using proof of concept implementations on real WSN hardware which is constrained by computing power in the order of a few MIPS, memory sizes of a few kilobytes, and small sized batteries. The results will remain usable in the future, as the vast amount, tight integration, and low-cost of future IoT devices require the combination of complex computation with resource constrained platforms

Abstracting Application Development for Resource Constrained Wireless Sensor Networks

Ubiquitous computing is a concept whereby computing is distributed across smart objects surrounding users, creating ambient intelligence. Ubiquitous applications use technologies such as the Internet, sensors, actuators, embedded computers, wireless communication, and new user interfaces. The Internet-of-Things (IoT) is one of the key concepts in the realization of ubiquitous computing, whereby smart objects communicate with each other and the Internet. Further, Wireless Sensor Networks (WSNs) are a sub-group of IoT technologies that consist of geographically distributed devices or nodes, capable of sensing and actuating the environment.WSNs typically contain tens to thousands of nodes that organize and operate autonomously to perform application-dependent sensing and sensor data processing tasks. The projected applications require nodes to be small in physical size and low-cost, and have a long lifetime with limited energy resources, while performing complex computing and communications tasks. As a result, WSNs are complex distributed systems that are constrained by communications, computing and energy resources. WSN functionality is dynamic according to the environment and application requirements. Dynamic multitasking, task distribution, task injection, and software updates are required in field experiments for possibly thousands of nodes functioning in harsh environments.The development of WSN application software requires the abstraction of computing, communication, data access, and heterogeneous sensor data sources to reduce the complexities. Abstractions enable the faster development of new applications with a better reuse of existing software, as applications are composed of high-level tasks that use the services provided by the devices to execute the application logic.The main research question of this thesis is: What abstractions are needed for application development for resource constrained WSNs? This thesis models WSN abstractions with three levels that build on top of each other: 1) node abstraction, 2) network abstraction, and 3) infrastructure abstraction. The node abstraction hides the details in the use of the sensing, communication, and processing hardware. The network abstraction specifies methods of discovering and accessing services, and distributing processing in the network. The infrastructure abstraction unifies different sensing technologies and infrastructure computing platforms.As a contribution, this thesis presents the abstraction model with a review of each abstraction level. Several designs for each of the levels are tested and verified with proofs of concept and analyses of field experiments. The resulting designs consist of an operating system kernel, a software update method, a data unification interface, and all abstraction levels combining abstraction called an embedded cloud.The presented operating system kernel has a scalable overhead and provides a programming approach similar to a desktop computer operating system with threads and processes. An over-the-air update method combines low overhead and robust software updating with application task dissemination. The data unification interface homogenizes the access to the data of heterogeneous sensor networks. A unification model is used for various use cases by mapping everything as measurements. The embedded cloud allows resource constrained WSNs to share services and data, and expand resources with other technologies. The embedded cloud allows the distributed processing of applications according to the available services. The applications are implemented as processes using a hardware independent description language that can be executed on resource constrained WSNs. The lessons of practical field experimenting are analyzed to study the importance of the abstractions. Software complexities encountered in the field experiments highlight the need for suitable abstractions.The results of this thesis are tested using proof of concept implementations on real WSN hardware which is constrained by computing power in the order of a few MIPS, memory sizes of a few kilobytes, and small sized batteries. The results will remain usable in the future, as the vast amount, tight integration, and low-cost of future IoT devices require the combination of complex computation with resource constrained platforms