Guard time optimisation and adaptation for energy efficient multi-hop TSCH networks

International audienceIn the IEEE 802.15.4-2015 standard, Time Slotted Channel Hopping (TSCH) aims to guarantee high-level network reliability by keeping nodes time-synchronised. In order to ensure successful communication between a sender and a receiver, the latter starts listening shortly before the expected time of a MAC layer frame's arrival. The offset between the time a node starts listening and the estimated time of frame arrival is called guard time and it aims to reduce the probability of missed frames due to clock drift. In this paper, we investigate the impact of the guard time on network performance. We identify that, when using the 6tisch minimal schedule, the most significant cause of energy consumption is idle listening during guard time. Therefore, we first perform mathematical modelling on a TSCH link to identify the guard time that maximises the energy-efficiency of the TSCH network in single hop topology. We then continue in multi-hop network, where we empirically adapt the guard time locally at each node depending its distance, in terms of hops, from the sink. Our performance evaluation results, conducted using the Contiki OS, demonstrate that the proposed decentralised guard time adaptation can reduce the energy consumption by up to 40%, without compromising network reliability

A Case for Time Slotted Channel Hopping for ICN in the IoT

Recent proposals to simplify the operation of the IoT include the use of Information Centric Networking (ICN) paradigms. While this is promising, several challenges remain. In this paper, our core contributions (a) leverage ICN communication patterns to dynamically optimize the use of TSCH (Time Slotted Channel Hopping), a wireless link layer technology increasingly popular in the IoT, and (b) make IoT-style routing adaptive to names, resources, and traffic patterns throughout the network--both without cross-layering. Through a series of experiments on the FIT IoT-LAB interconnecting typical IoT hardware, we find that our approach is fully robust against wireless interference, and almost halves the energy consumed for transmission when compared to CSMA. Most importantly, our adaptive scheduling prevents the time-slotted MAC layer from sacrificing throughput and delay

Designing Time Slotted Channel Hopping and Information-Centric Networking for IoT

International audienceRecent proposals to simplify the operation of the IoT include the use of Information Centric Networking (ICN) paradigms. While this is promising, several challenges remain. In this paper, our core contributions (a) leverage ICN communication patterns to dynamically optimize the use of TSCH (Time Slotted Channel Hopping), a wireless link layer technology increasingly popular in the IoT, and (b) make IoT-style routing adaptive to names, resources, and traffic patterns throughout the network -- both without cross-layering

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

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

Otimização da eficiência energética em redes operando com tsch: avaliação analítica de uma implementação prática.

The IEEE 802.15.4-2015 standard defines a number of Medium Access Control (MAC) layer protocols for low power wireless communications, which is desirable for constrained Internet of Things (IoT) devices. Originally defined in IEEE 802.15.4e amendment, the Time Slotted Channel Hopping (TSCH) is recently attracting the attention from the research community, due to its reduced contention (time scheduling) and robustness (channel hopping). However, the TSCH needs a certain level of synchronization between the nodes, which can lead to a higher energy consumption. A guard time mechanism is implemented to ensure that the nodes will hear the frames even if they are not perfectly synchronized. In this work, we implement the Guard Beacon strategy, aiming to reduce the guard time, and present a realistic energy consumption model for a Contiki OS-based TSCH networks. The analytical values have a good match with the results obtained from the Contiki Powertrace Tool running on a real TSCH network and demonstrate that the proposed scheme can reduce the overall power consumption of each node by 13.05%.O padrão IEEE 802.15.4-2015 define novos protocolos para a camada de acesso ao meio (MAC, do inglês Medium Access Control) com foco em redes de comunicação sem fio com baixo consumo de energia, o que é desejável para dispositivos de Internet das Coisas (IoT, do inglês Internet of Things) que apresentam restrições energéticas. Originalmente definido na emenda IEEE 802.15.4e, o esquema de Salto de Canais por Intervalo de Tempo (TSCH, do inglês Time Slotted Channel Hopping) tem atraído atenção da comunidade científica devido ao nível reduzido de contenção (agendamento no tempo) e robustez (salto de canais). Entretanto, para operar corretamente o TSCH necessita de um determinado nível de sincronização entre os nós da rede, o que pode levar a um maior consumo de energia. Um mecanismo de tempo de guarda é implementado para assegurar que os nós irão “ouvir” os pacotes ainda que não estejam perfeitamente sincronizados. Neste trabalho, implementa-se a estratégia de Guard Beacon visando reduzir o tempo de guarda necessário, e se apresenta um modelo de consumo de energia realista para redes operando com TSCH e Sistema Operacional Contiki. Os resultados analíticos têm boa precisão quando comparados com os resultados obtidos de uma rede TSCH real através da ferramenta Powertrace do Contiki e demonstram que o esquema proposto pode reduzir o consumo de energia geral de cada nó em até 13,05%

Kommunikation und Bildverarbeitung in der Automation

In diesem Open-Access-Tagungsband sind die besten Beiträge des 9. Jahreskolloquiums "Kommunikation in der Automation" (KommA 2018) und des 6. Jahreskolloquiums "Bildverarbeitung in der Automation" (BVAu 2018) enthalten. Die Kolloquien fanden am 20. und 21. November 2018 in der SmartFactoryOWL, einer gemeinsamen Einrichtung des Fraunhofer IOSB-INA und der Technischen Hochschule Ostwestfalen-Lippe statt. Die vorgestellten neuesten Forschungsergebnisse auf den Gebieten der industriellen Kommunikationstechnik und Bildverarbeitung erweitern den aktuellen Stand der Forschung und Technik. Die in den Beiträgen enthaltenen anschaulichen Beispiele aus dem Bereich der Automation setzen die Ergebnisse in den direkten Anwendungsbezug