We have witnessed the Fixed Internet emerging with virtually every computer being connected today; we are currently witnessing the emergence of the Mobile Internet with the exponential explosion of smart phones, tablets and net-books. However, both will be dwarfed by the anticipated emergence of the Internet of Things (IoT), in which everyday objects are able to connect to the Internet, tweet or be queried. Whilst the impact onto economies and societies around the world is undisputed, the technologies facilitating such a ubiquitous connectivity have struggled so far and only recently commenced to take shape.To this end, this paper introduces in a timely manner the cornerstones of a technically and commercially viable IoT which includes a detailed discussion on the particular standard of choice at each protocol layer. This stack is shown to meet the important criteria of power-efficiency, reliability and Internet connectivity. Industrial applications have been the early adopters of this stack, which has become the de-facto standard, thereby bootstraping early IoT developments.Corroborated throughout this paper and by emerging industry alliances, we believe that a standardized approach, using latest developments in the IEEE 802.15.4 and IETF working groups, is the only way forward. We introduce and relate key embodiments of the power-efficient IEEE 802.15.4-2006 PHY layer, the power-saving and reliable IEEE 802.15.4e MAC layer, the IETF 6LoWPAN adaptation layer enabling universal Internet connectivity, the IETF ROLL routing protocol enabling availability, and finally the IETF CoAP enabling seamless transport and support of Internet applications.The protocol stack proposed in the present work converges towards the standardized notations of the ISO/OSI and TCP/IP stacks. What thus seemed impossible some years back, i.e., building a clearly defined, standards-compliant and Internet-compliant stack given the extreme restrictions of IoT networks, is commencing to become reality.
Abstract-This paper capitalizes on two emerging trends, i.e. the growing use of wireless at the edge of industrial control networks and the growing interest to integrate IP into said networks. This is facilitated by recent design contributions from the IEEE and the IETF, where the former developed a highly efficient deterministic time-frequency scheduled medium access control protocol in form of IEEE 802.15.4e TSCH and the latter IPv6 networking paradigms in form of 6LoWPAN/ROLL, and scheduling approaches in form of 6TiSCH. The focus of the present work is on advancing the state of the art of deterministic 6TiSCH schedules towards more flexible but equally reliable distributed approaches. In addition, this paper aims to introduce the first implementation of 6TiSCH networks for factory automation environments: it outlines the challenges faced to overcome the scalability issues inherent to multi-hop dense low-power networks; the experimental results confirm that the naturally unreliable radio medium can support time-critical and reliable applications. These developments pave the way for wireless industry-grade monitoring approaches.
The Internet of Things (IoT) has drawn an enormous attention into the scientific community thanks to unimaginable before applications newly available in everyday life. The technological landscape behind the implied surge of automated interactions among humans and machines has been shaped by plugging into the Internet very low power devices that can perform monitoring and actuation operations through very cheap circuitry. The most challenging IoT scenarios include deployments of low power devices dispersed over wide geographical areas. In such scenarios, satellites will play a key role in bridging the gap towards a pervasive IoT able to easily handle disaster recovery scenarios (earthquakes, tsunamis, and flash floods, etc.), where the presence of a resilient backhauling communications infrastructure is crucial. In these scenarios, Direct-to-Satellite IoT (DtS-IoT) connectivity is preferred as no intermediate ground gateway is required, facilitating and speeding up the deployment of wide coverage IoT infrastructure. In this work, an in-depth yet thorough survey on the state-of-the-art of DtS-IoT is presented. The available physical layer techniques specifically designed for the IoT satellite link are described, and the suitability of both the current Medium Access Control protocol and the upper layer protocols to communicate over space links will be argued. We also discuss the design of the overall satellite LEO constellation and topology to be considered in DtS-IoT networks.
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