Surfing the Internet-of-Things: lightweight access and control of wireless sensor networks using industrial low power protocols

Internet-of-Things (IoT) is emerging to play an important role in the continued advancement of information and communication technologies. To accelerate industrial application developments, the use of web services for networking applications is seen as important in IoT communications. In this paper, we present a RESTful web service architecture for energy-constrained wireless sensor networks (WSNs) to enable remote data collection from sensor devices in WSN nodes. Specifically, we consider both IPv6 protocol support in WSN nodes as well as an integrated gateway solution to allow any Internet clients to access these nodes.We describe the implementation of a prototype system, which demonstrates the proposed RESTful approach to collect sensing data from a WSN. A performance evaluation is presented to illustrate the simplicity and efficiency of our proposed scheme

Energy-Efficient Communication in Wireless Networks

This chapter describes the evolution of, and state of the art in, energy‐efficient techniques for wirelessly communicating networks of embedded computers, such as those found in wireless sensor network (WSN), Internet of Things (IoT) and cyberphysical systems (CPS) applications. Specifically, emphasis is placed on energy efficiency as critical to ensuring the feasibility of long lifetime, low‐maintenance and increasingly autonomous monitoring and control scenarios. A comprehensive summary of link layer and routing protocols for a variety of traffic patterns is discussed, in addition to their combination and evaluation as full protocol stacks

Supporting Cyber-Physical Systems with Wireless Sensor Networks: An Outlook of Software and Services

Sensing, communication, computation and control technologies are the essential building blocks of a cyber-physical system (CPS). Wireless sensor networks (WSNs) are a way to support CPS as they provide fine-grained spatial-temporal sensing, communication and computation at a low premium of cost and power. In this article, we explore the fundamental concepts guiding the design and implementation of WSNs. We report the latest developments in WSN software and services for meeting existing requirements and newer demands; particularly in the areas of: operating system, simulator and emulator, programming abstraction, virtualization, IP-based communication and security, time and location, and network monitoring and management. We also reflect on the ongoing efforts in providing dependable assurances for WSN-driven CPS. Finally, we report on its applicability with a case-study on smart buildings

Pervasive service discovery in low-power and lossy networks

Pervasive Service Discovery (SD) in Low-power and Lossy Networks (LLNs) is expected to play a major role in realising the Internet of Things (IoT) vision. Such a vision aims to expand the current Internet to interconnect billions of miniature smart objects that sense and act on our surroundings in a way that will revolutionise the future. The pervasiveness and heterogeneity of such low-power devices requires robust, automatic, interoperable and scalable deployment and operability solutions. At the same time, the limitations of such constrained devices impose strict challenges regarding complexity, energy consumption, time-efficiency and mobility. This research contributes new lightweight solutions to facilitate automatic deployment and operability of LLNs. It mainly tackles the aforementioned challenges through the proposition of novel component-based, automatic and efficient SD solutions that ensure extensibility and adaptability to various LLN environments. Building upon such architecture, a first fully-distributed, hybrid pushpull SD solution dubbed EADP (Extensible Adaptable Discovery Protocol) is proposed based on the well-known Trickle algorithm. Motivated by EADPs’ achievements, new methods to optimise Trickle are introduced. Such methods allow Trickle to encompass a wide range of algorithms and extend its usage to new application domains. One of the new applications is concretized in the TrickleSD protocol aiming to build automatic, reliable, scalable, and time-efficient SD. To optimise the energy efficiency of TrickleSD, two mechanisms improving broadcast communication in LLNs are proposed. Finally, interoperable standards-based SD in the IoT is demonstrated, and methods combining zero-configuration operations with infrastructure-based solutions are proposed. Experimental evaluations of the above contributions reveal that it is possible to achieve automatic, cost-effective, time-efficient, lightweight, and interoperable SD in LLNs. These achievements open novel perspectives for zero-configuration capabilities in the IoT and promise to bring the ‘things’ to all people everywhere

A Survey on Resource Management in IoT Operating Systems

Recently, the Internet of Things (IoT) concept has attracted a lot of attention due to its capability to translate our physical world into a digital cyber world with meaningful information. The IoT devices are smaller in size, sheer in number, contain less memory, use less energy, and have more computational capabilities. These scarce resources for IoT devices are powered by small operating systems (OSs) that are specially designed to support the IoT devices' diverse applications and operational requirements. These IoT OSs are responsible for managing the constrained resources of IoT devices efficiently and in a timely manner. In this paper, discussions on IoT devices and OS resource management are provided. In detail, the resource management mechanisms of the state-of-the-art IoT OSs, such as Contiki, TinyOS, and FreeRTOS, are investigated. The different dimensions of their resource management approaches (including process management, memory management, energy management, communication management, and file management) are studied, and their advantages and limitations are highlighted

Experimental study on low power wireless sensor network protocols with native IP connectivity for building automation

The thesis performs an experimental study on the performance of 6LoWPAN network stack running on the latest TI CC2650EM, and evaluates the possibility of implementing the chip in industrial building automation system. The experiment and evaluation is done in three aspects that the industrial mostly concern – stability, latency and reliability, and power consumption. Although there are already several mature network protocols specially designed for the IoT devices, IPv6 based 6LoWPAN network stack is highly compatible with the TCP/IP based Internet. The self-healing meshing and simple IP-routing mechanism makes 6LoWPAN very attractive to both developers and manufacturers. Contiki operating system provides a clear layer-separated implementation for the 6LoWPAN stack, and introduces a radio duty cycling protocol for saving power. Therefore, a black-boxed performance test on Contiki OS with 6LoWPAN network stack running on the TI CC2650EM board. Through the performance tests and comparison between the network protocols for low-power operations, the combination of TI CC2650 platform and Contiki OS with 6LoWPAN network stack is proved to be a promising solution for future building automation systems

Discovery and Group Communication for Constrained Internet of Things Devices using the Constrained Application Protocol

The ubiquitous Internet is rapidly spreading to new domains. This expansion of the Internet is comparable in scale to the spread of the Internet in the ’90s. The resulting Internet is now commonly referred to as the Internet of Things (IoT) and is expected to connect about 50 billion devices by the year 2020. This means that in just five years from the time of writing this PhD the number of interconnected devices will exceed the number of humans by sevenfold. It is further expected that the majority of these IoT devices will be resource constrained embedded devices such as sensors and actuators. Sensors collect information about the physical world and inject this information into the virtual world. Next processing and reasoning can occur and decisions can be taken to enact upon the physical world by injecting feedback to actuators. The integration of embedded devices into the Internet introduces new challenges, since many of the existing Internet technologies and protocols were not designed for this class of constrained devices. These devices are typically optimized for low cost and power consumption and thus have very limited power, memory, and processing resources and have long sleep periods. The networks formed by these embedded devices are also constrained and have different characteristics than those typical in todays Internet. These constrained networks have high packet loss, low throughput, frequent topology changes and small useful payload sizes. They are referred to as LLN. Therefore, it is in most cases unfeasible to run standard Internet protocols on this class of constrained devices and/or LLNs. New or adapted protocols that take into consideration the capabilities of the constrained devices and the characteristics of LLNs, are required. In the past few years, there were many efforts to enable the extension of the Internet technologies to constrained devices. Initially, most of these efforts were focusing on the networking layer. However, the expansion of the Internet in the 90s was not due to introducing new or better networking protocols. It was a result of introducing the World Wide Web (WWW), which made it easy to integrate services and applications. One of the essential technologies underpinning the WWW was the Hypertext Transfer Protocol (HTTP). Today, HTTP has become a key protocol in the realization of scalable web services building around the Representational State Transfer (REST) paradigm. The REST architectural style enables the realization of scalable and well-performing services using uniform and simple interfaces. The availability of an embedded counterpart of HTTP and the REST architecture could boost the uptake of the IoT. Therefore, more recently, work started to allow the integration of constrained devices in the Internet at the service level. The Internet Engineering Task Force (IETF) Constrained RESTful Environments (CoRE) working group has realized the REST architecture in a suitable form for the most constrained nodes and networks. To that end the Constrained Application Protocol (CoAP) was introduced, a specialized RESTful web transfer protocol for use with constrained networks and nodes. CoAP realizes a subset of the REST mechanisms offered by HTTP, but is optimized for Machine-to-Machine (M2M) applications. This PhD research builds upon CoAP to enable a better integration of constrained devices in the IoT and examines proposed CoAP solutions theoretically and experimentally proposing alternatives when appropriate. The first part of this PhD proposes a mechanism that facilitates the deployment of sensor networks and enables the discovery, end-to-end connectivity and service usage of newly deployed sensor nodes. The proposed approach makes use of CoAP and combines it with Domain Name System (DNS) in order to enable the use of userfriendly Fully Qualified Domain Names (FQDNs) for addressing sensor nodes. It includes the automatic discovery of sensors and sensor gateways and the translation of HTTP to CoAP, thus making the sensor resources globally discoverable and accessible from any Internet-connected client using either IPv6 addresses or DNS names both via HTTP or CoAP. As such, the proposed approach provides a feasible and flexible solution to achieve hierarchical self-organization with a minimum of pre-configuration. By doing so we minimize costly human interventions and eliminate the need for introducing new protocols dedicated for the discovery and organization of resources. This reduces both cost and the implementation footprint on the constrained devices. The second, larger, part of this PhD focuses on using CoAP to realize communication with groups of resources. In many IoT application domains, sensors or actuators need to be addressed as groups rather than individually, since individual resources might not be sufficient or useful. A simple example is that all lights in a room should go on or off as a result of the user toggling the light switch. As not all IoT applications may need group communication, the CoRE working group did not include it in the base CoAP specification. This way the base protocol is kept as efficient and as simple as possible so it would run on even the most constrained devices. Group communication and other features that might not be needed by all devices are standardized in a set of optional separate extensions. We first examined the proposed CoAP extension for group communication, which utilizes Internet Protocol version 6 (IPv6) multicasts. We highlight its strengths and weaknesses and propose our own complementary solution that uses unicast to realize group communication. Our solution offers capabilities beyond simple group communication. For example, we provide a validation mechanism that performs several checks on the group members, to make sure that combining them together is possible. We also allow the client to request that results of the individual members are processed before they are sent to the client. For example, the client can request to obtain only the maximum value of all individual members. Another important optional extension to CoAP allows clients to continuously observe resources by registering their interest in receiving notifications from CoAP servers once there are changes to the values of the observed resources. By using this publish/subscribe mechanism the client does not need to continuously poll the resource to find out whether it has changed its value. This typically leads to more efficient communication patterns that preserve valuable device and LLN resources. Unfortunately CoAP observe does not work together with the CoAP group communication extension, since the observe extension assumes unicast communication while the group communication extension only support multicast communication. In this PhD we propose to extend our own group communication solution to offer group observation capabilities. By combining group observation with group processing features, it becomes possible to notify the client only about certain changes to the observed group (e.g., the maximum value of all group members has changed). Acknowledging that the use of multicast as well as unicast has strengths and weaknesses we propose to extend our unicast based solution with certain multicast features. By doing so we try to combine the strengths of both approaches to obtain a better overall group communication that is flexible and that can be tailored according to the use case needs. Together, the proposed mechanisms represent a powerful and comprehensive solution to the challenging problem of group communication with constrained devices. We have evaluated the solutions proposed in this PhD extensively and in a variety of forms. Where possible, we have derived theoretical models and have conducted numerous simulations to validate them. We have also experimentally evaluated those solutions and compared them with other proposed solutions using a small demo box and later on two large scale wireless sensor testbeds and under different test conditions. The first testbed is located in a large, shielded room, which allows testing under controlled environments. The second testbed is located inside an operational office building and thus allows testing under normal operation conditions. Those tests revealed performance issues and some other problems. We have provided some solutions and suggestions for tackling those problems. Apart from the main contributions, two other relevant outcomes of this PhD are described in the appendices. In the first appendix we review the most important IETF standardization efforts related to the IoT and show that with the introduction of CoAP a complete set of standard protocols has become available to cover the complete networking stack and thus making the step from the IoT into the Web of Things (WoT). Using only standard protocols makes it possible to integrate devices from various vendors into one bigWoT accessible to humans and machines alike. In the second appendix, we provide an alternative solution for grouping constrained devices by using virtualization techniques. Our approach focuses on the objects, both resource-constrained and non-constrained, that need to cooperate by integrating them into a secured virtual network, named an Internet of Things Virtual Network or IoT-VN. Inside this IoT-VN full end-to-end communication can take place through the use of protocols that take the limitations of the most resource-constrained devices into account. We describe how this concept maps to several generic use cases and, as such, can constitute a valid alternative approach for supporting selected applications

Multitasking on Wireless Sensor Networks

A Wireless Sensor Network (WSN) is a loose interconnection among distributed embedded devices called motes. Motes have constrained sensing, computing, and communicating resources and operate for a long period of time on a small energy supply. Although envisioned as a platform for facilitating and inspiring a new spectrum of applications, after a decade of research the WSN is limited to collecting data and sporadically updating system parameters. Programming other applications, including those that have real-time constraints, or designing WSNs operating with multiple applications require enhanced system architectures, new abstractions, and design methodologies. This dissertation introduces a system design methodology for multitasking on WSNs. It allows programmers to create an abstraction of a single, integrated system running with multiple tasks. Every task has a dedicated protocol stack. Thus, different tasks can have different computation logics and operate with different communication protocols. This facilitates the execution of heterogeneous applications on the same WSN and allows programmers to implement a variety of system services. The services that have been implemented provide energy-monitoring, tasks scheduling, and communication between the tasks. The experimental section evaluates implementations of the WSN software designed with the presented methodology. A new set of tools for testbed deployments is introduced and used to test examples of WSNs running with applications interacting with the physical world. Using remote testbeds with over 100 motes, the results show the feasibility of the proposed methodology in constructing a robust and scalable WSN system abstraction, which can improve the run-time performance of applications, such as data collection and point-to-point streaming

A survey of potential security issues in existing wireless sensor network protocols

The increasing pervasiveness of wireless sensor networks (WSNs) in diverse application domains including critical infrastructure systems, sets an extremely high security bar in the design of WSN systems to exploit their full benefits, increasing trust while avoiding loss. Nevertheless, a combination of resource restrictions and the physical exposure of sensor devices inevitably cause such networks to be vulnerable to security threats, both external and internal. While several researchers have provided a set of open problems and challenges in WSN security and privacy, there is a gap in the systematic study of the security implications arising from the nature of existing communication protocols in WSNs. Therefore, we have carried out a deep-dive into the main security mechanisms and their effects on the most popular protocols and standards used in WSN deployments, i.e., IEEE 802.15.4, Berkeley media access control for low-power sensor networks, IPv6 over low-power wireless personal area networks, outing protocol for routing protocol for low-power and lossy networks (RPL), backpressure collection protocol, collection tree protocol, and constrained application protocol, where potential security threats and existing countermeasures are discussed at each layer of WSN stack. This paper culminates in a deeper analysis of network layer attacks deployed against the RPL routing protocol. We quantify the impact of individual attacks on the performance of a network using the Cooja network simulator. Finally, we discuss new research opportunities in network layer security and how to use Cooja as a benchmark for developing new defenses for WSN systems

Pile de protocoles pour des réseaux des capteurs avec récupération d'énergie

This thesis concerns energy efficient protocols for harvested wireless sensor networks. It is a part of an industrial Internet of Things project. STMicroelectronics started the GreenNet project with the objective to develop and design a new generation of harvesting smart objects to be integrated in the Internet of Things. The GreenNet platform is novel with respect to the existing solutions due to its small size that implies a small energy buffer and small harvesting capabilities. This aspect makes the standard protocols and precedent solutions not directly applicable on this extremely low power platform. In this dissertation, we analyse standard protocols and existing solutions to identify their issues in the gn platform. Then, we provide protocol and algorithm adaptations to make feasible the concept of auto configurable and sustainable networks of GreenNet nodes. We proposed MCBT, an energy efficient protocol for the bootstrap procedure. It enables low power nodes to be enrolled in mh mc wireless sensor networks thanks to the network support for enrolling new nodes. It represents an energy efficient solution that extends the standard protocol. We proposed STADA, a sustainable algorithm to adapt the node activity according to the available energy and traffic conditions. STADA is based on a weighted function that takes into account the energy present in the battery, the energy harvesting rate, and network traffic. In this way, the algorithm takes into account all main parameters to adapt the energy consumption and improve the node performance. To make the harvested network more efficient according to light variations, we proposed a novel metric that makes the path choice a simple process. With the Expected Delay, we synthesize all network parameters in a single monotonic variable that facilitates the path choice in mh harvesting wireless sensor networks. All proposed solutions are designed to work with standard beacon-enabled IEEE 802.15.4 protocols and are easily portable on the future version of IEEE 802.15.4e. We validated the proposed protocols with emulations and simulations. The evaluation results shown better performance in terms of energy consumption and quality of service.Cette thèse vise à améliorer la pile de protocoles pour réseaux de capteurs sans fil à récupération d'énergie afin de les rendre autonomes dans un contexte multi-saut. Elle s'inscrit dans le projet GreenNet de STMicroelectronics qui a pour objectif de concevoir et développer une nouvelle génération d'objets intelligent basés sur la récupération d'énergie ambiente en vue de l'intégration dans l'Internet des Objets. L'originalité de la plateforme GreenNet repose sur sa petite taille qui implique une faible capacité de stockage d'énergie ainsi qu'une faible capacité de récupération d'énergie. Avec un si faible budget d'énergie, les protocoles standards ou les solutions proposées par les communautés académique/industrielle ne permettant pas d'assurer un fonctionnement autonome de ces réseaux. Dans cette thèse, nous analysons les protocoles standards et les solutions existantes pour identifier leurs limites avec la plateforme GreenNet. Ensuite, nous proposons 3 contributions afin de permettre cette autonomie. La première contribution est MCBT, un protocole permettant d'accélérer la découverte et le rattachement de nouveaux noeuds à un réseau multi saut et multi-canaux en formation ou existent. Ce protocole réduit efficacement l'énergie dépensée dans cette phase fortement consommatrice. La deuxième contribution est STADA, un algorithme adaptant l'activité des capteurs en fonction des conditions locales de trafic et d'énergie disponible. STADA est basé sur une fonction de pondération qui tient compte de l'énergie présente dans la batterie, du taux de récupération d'énergie et du trafic local. Enfin, notre troisième contribution propose une nouvelle métrique de routage basée sur Expected Delay synthétisant en une seule variable monotone des facteurs tels que l'éloignement au puits, les chemins bénéficiant d'un ordonnancement de relayage de paquet privilégié et de périodes cumulées d'activité des radios sur le chemin favorable. Toutes les solutions proposées sont conçues pour fonctionner avec la norme IEEE 802.15.4 slotté et sont facilement transposables à son évolution définie par la norme IEEE 802.15.4e. Nous avons validé les protocoles proposés grâce à un simulateur émulant des noeuds réels (Cooja) et au simulateur WSNet. Les résultats ont montré de meilleures performances en termes de consommation d'énergie et de qualité de service par rapport à l'existant