Experimental Clock Calibration\\on a Crystal-Free Mote-on-a-Chip

The elimination of the off-chip frequency reference, typically a crystal oscillator, would bring important benefits in terms of size, price and energy efficiency to IEEE802.15.4 compliant radios and systems-on-chip. The stability of on-chip oscillators is orders of magnitude worse than that of a crystal. It is known that as the temperature changes, they can drift more than 50 ppm/{\deg}C. This paper presents the result of an extensive experimental study. First, we propose mechanisms for crystal-free radios to be able to track an IEEE802.15.4 join proxy, calibrate the on-chip oscillators and maintain calibration against temperature changes. Then, we implement the resulting algorithms on a crystal-free platform and present the results of an experimental validation. We show that our approach is able to track a crystal-based IEEE802.15.4-compliant join proxy and maintain the requested radio frequency stability of +/-40 ppm, even when subject to temperature variation of 2{\deg}C/min.Comment: CNERT: Computer and Networking Experimental Research using Testbeds, in conjunction with IEEE INFOCOM 2019, April 29 - May 2, 2019, Paris, Franc

Distributed Cyber-Physical Systems with Unmanned Aerial Vehicles

This thesis discusses the merger between Unmanned Aerial Vehicles (UAVs) and static wireless sensor networks (WSNs). It explores and demonstrates the use of UAVs as mobile sinks to collect data from static sensor networks. A communication protocol is developed to approach a 100% data reliability while trying to maximise the speed of the UAV. An energy model and speed versus reliability models are developed and tested using MATLAB. Mathematical models are developed to calculate the energy needed by nodes in such a system. The energy model developed is used to inform the design of recharging systems with wireless power transfer and consider energy harvesting opportunities. The protocol developed is an asynchronous communication protocol. It is devel- oped in ContikiOS on top of ContikiMAC radio duty cycling protocol using the Rime communication stack. A series of indoor and outdoor tests are conducted using real hardware and the performance of this protocol is compared with CTP. The results show that the protocol developed has 100% data reliability when the speed of the UAV is less than 12m/s. Based on the performance results obtained, subsequent numerical analysis shows that operational lifetime of nodes under these conditions can extend to 1.8 years using a typical 2400 mAH battery. This work is one of the rst practical demonstrations of UAVs with WSN and highlights a number of consequential research questions

Link-layer Security in TSCH Networks: Effect on Slot Duration

International audienceThe IEEE802.15.4e-2012 standard is widely used in multi-hop wireless Industrial Internet of Things (IIoT)applications. In the Time-Slotted Channel Hopping (TSCH) mode, nodes are synchronized, and time iscut into timeslots. A schedule orchestrates all communications, resulting in high reliability and low poweroperations. A timeslot must be long enough for a node to send a data frame to its neighbor, and for thatneighbor to send back an acknowledgment. Shorter timeslots enable higher bandwidth and lower latency, yetthe minimal timeslot duration is limited by how long link-layer security operations take. We evaluate theoverhead of link-layer security in TSCH networks in terms of minimal timeslot length, memory footprint,and energy consumption. We implement full link-layer security on a range of hardware platforms, exploringdierent hardware/software implementation strategies. Through an extensive measurement campaign, wequantify the advantage of hardware accelerations for link-layer security, and show how the minimal durationof a timeslot varies between 9 ms and 88 ms for the most common conguration, depending on hardwaresupport. Furthermore, we also highlighted the impact that the timeslot duration has on both high-levelapplication design and energy consumption

Industry 4.0: Industrial IoT Enhancement and WSN Performance Analysis

L'abstract è presente nell'allegato / the abstract is in the attachmen

A Review of Low-end, Middle-end and High-end IoT Devices

Internet of Things (IoT) devices play a crucial role in the overall development of IoT in providing countless applications in various areas. Due to the increasing interest and rapid technological growth of sensor technology, which have certainly revolutionized the way we live today, a need to provide a detailed analysis of the embedded platforms and boards is consequential. This paper presents a comprehensive survey of the recent and most-widely used commercial and research embedded systems and boards in different classification emphasizing their key attributes including processing and memory capabilities, security features, connectivity and communication interfaces, size, cost and appearance, operating system (OS) support, power specifications and battery life and listing some interesting projects for each device. Through this exploration and discussion, readers can have an overall understanding on this area and foster more subsequent studies

Red mallada de nodos Contiki para monitorización de temperaturas y envío de alertas por SMS

Treball Final de Grau en Enginyeria Informàtica. Codi: EI1054. Curs acadèmic: 2016-2017En esta memoria se va a proceder a describir el diseño y proceso de desarrollo de una red de monitorización del entorno que envía periódicamente los datos recopilados y es capaz de enviar alarmas por SMS. Este documento recoge los detalles del proceso de diseño, la implementación y pruebas realizadas para la correcta implementación del proyecto. El diseño de la red de monitorización incluye el uso de nodos con el sistema operativo Contiki para recopilar los datos, de una Raspberry Pi para recibir los datos recopilados y enviar SMS en el caso que alguno de ellos sea una alarma, y de un nodo Border Router que permite la comunicación bidireccional entre los nodos Contiki y la Raspberry Pi. La comunicación entre los nodos Contiki y el Border Router se realiza mediante el protocolo RPL y la comunicación entre el Border Router y la Raspberry Pi se realiza sobre el protocolo Ethernet. Todos los mensajes de la red son codificados en JSON y enviados utilizando el protocolo CoAP. Los nodos Contiki son configurables

Experimental Clock Calibration on a Crystal-Free Mote-on-a-Chip

International audienceThe elimination of the off-chip frequency reference,typically a crystal oscillator, would bring important benefits in terms of size, price and energy efficiency to IEEE802.15.4compliant radios and systems-on-chip. The stability of on-chip oscillators is orders of magnitude worse than that of a crystal.It is known that as the temperature changes, they can drift more than50ppm/◦C. This paper presents the result of an extensive experimental study. First, we propose mechanisms for crystal-free radios to be able to track an IEEE802.15.4 join proxy, calibrate the on-chip oscillators and maintain calibration against temperature changes. Then, we implement the resulting algorithms on a crystal-free platform and present the results of an experimental validation. We show that our approach is able to track a crystal-based IEEE802.15.4-compliant join proxy and maintain the requested radio frequency stability of±40ppm, even when subject to temperature variation of2◦C/min