Synchronous and Concurrent Transmissions for Consensus in Low-Power Wireless

With the emergence of the Internet of Things, autonomous vehicles and the Industry 4.0, the need for dependable yet adaptive network protocols is arising. Many of these applications build their operations on distributed consensus. For example, UAVs agree on maneuvers to execute, and industrial systems agree on set-points for actuators.Moreover, such scenarios imply a dynamic network topology due to mobility and interference, for example. Many applications are mission- and safety-critical, too.Failures could cost lives or precipitate economic losses.In this thesis, we design, implement and evaluate network protocols as a step towards enabling a low-power, adaptive and dependable ubiquitous networking that enables consensus in the Internet of Things. We make four main contributions:- We introduce Orchestra that addresses the challenge of bringing TSCH (Time Slotted Channel Hopping) to dynamic networks as envisioned in the Internet of Things. In Orchestra, nodes autonomously compute their local schedules and update automatically as the topology evolves without signaling overhead. Besides, it does not require a central or distributed scheduler. Instead, it relies on the existing network stack information to maintain the schedules.- We present A2 : Agreement in the Air, a system that brings distributed consensus to low-power multihop networks. A2 introduces Synchrotron, a synchronous transmissions kernel that builds a robust mesh by exploiting the capture effect, frequency hopping with parallel channels, and link-layer security. A2 builds on top of this layer and enables the two- and three-phase commit protocols, and services such as group membership, hopping sequence distribution, and re-keying.- We present Wireless Paxos, a fault-tolerant, network-wide consensus primitive for low-power wireless networks. It is a new variant of Paxos, a widely used consensus protocol, and is specifically designed to tackle the challenges of low-power wireless networks. By utilizing concurrent transmissions, it provides a dependable low-latency consensus.- We present BlueFlood, a protocol that adapts concurrent transmissions to Bluetooth. The result is fast and efficient data dissemination in multihop Bluetooth networks. Moreover, BlueFlood floods can be reliably received by off-the-shelf Bluetooth devices such as smartphones, opening new applications of concurrent transmissions and seamless integration with existing technologies

Communication Multi-Canaux Économe en Consommation d’Énergie dans les Réseaux de Capteurs Sans Fils.

Les trois principaux axes qui déterminent la performance des protocoles de la couche MAC dans les réseaux de capteurs sans fils sont: la consommation d’énergie, le débit et la latence, quoique l’inconvénient majeur qui entrave le WSN est la perte (épuisement) d’énergie. Des études ont prouvé que la perte d’énergie est réduite en augmentant la période de sommeil, et que le débit et la latence sont principalement affectée par les collisions. Dans notre contribution, nous avons essayé de combiner TDMA avec FDMA pour diminuer la consommation d’énergie en augmentant les périodes de sommeil et en réduisant les collisions par l’utilisation du multi-canal. Notre solution est basée sur le concept de Block Design. Nous combinons les deux types de bloc Design: Latin Square/Rectangle et BIBD pour développer une allocation distribuée et dynamique des slots et des canaux. Afin d’obtenir une allocation dynamique, nous avons divisé le Latin Square à Latin Rectangles, où le Latin Square fait référence à une super-trame et chaque Latin Rectangle se réfère à une trame, tandis que une trame est un ensemble de slots. Dans notre base récepteur méthode, chaque nœud génère le Latin Square suivant une formule unifiée et exécute un algorithme pour déterminer le nombre de slots par trame, le nombre de trame par super-trame, et la réservation de canal et de slot de lui-même et celle de tous ces voisins, afin que nous ayons une allocation distribuée de slots et des canaux. Nous avons utilisé le simulateur NS-3 pour valider les principaux aspects de la performance de notre méthode qui sont: la consommation d’énergie, le débit et la latenc

Multichannel Cross-Layer Routing for Sensor Networks

Wireless Sensor Networks are ad-hoc networks that consist of sensor nodes that typically use low-power radios to connect to the Internet. The channels used by the low-power radio often suffer from interference from the other devices sharing the same frequency. By using multichannel communication in wireless networks, the effects of interference can be mitigated to enable the network to operate reliably. This thesis investigates an energy efficient multichannel protocol in Wireless Sensor Networks. It presents a new decentralised multichannel tree-building protocol with a centralised controller for ad-hoc sensor networks. The proposed protocol alleviates the effect of interference, which results in improved network efficiency, stability, and link reliability. The protocol detects the channels that suffer interference in real-time and switches the sensor nodes from those channels. It takes into account all available channels and aims to use the spectrum efficiently by transmitting on several channels. In addition to the use of multiple channels, the protocol reconstructs the topology based on the sensor nodes’ residual energy, which can prolong the network lifetime. The sensor nodes’ energy consumption is reduced because of the multichannel protocol. By using the lifetime energy spanning tree algorithm proposed in this thesis, energy consumption can be further improved by balancing the energy load in the network. This solution enables sensor nodes with less residual energy to remain functional in the network. The benefits of the proposed protocol are described in an extensive performance evaluation of different scenarios in this thesis

Evaluación del rendimiento del protocolo 6LoWPAN sobre una plataforma de Hardware y Software libre /

Las redes de sensores inalámbricos (WSN – Wireless Sensor Networks) han ido evolucionando en los últimos años, siendo su uso más frecuente en soluciones para diversas áreas, dentro de las que se destacan el monitoreo industrial, el estudio de variables ambientales y climatológicas, la domótica y aplicaciones militares [1]. Estas redes brindan soluciones a los problemas en las áreas mencionadas, que no son ajenas a la actualidad que vive la Región Caribe Colombiana. Sin embargo, las WSN presentan diversas dificultades, siendo las más usuales las asociadas al consumo energético [2] y de recursos de procesamiento [3]. Por ello, este trabajo se centra en el estudio del rendimiento del direccionamiento IPV6 a través del protocolo 6LowPan [4], el cual direcciona estos dos aspectos entre otros, mediante la realización de pruebas de rendimiento sobre plataformas de hardware y software libre a través de escenarios con uno y dos nodos conectados a un sumidero que permita evaluar el tiempo de transmisión de paquetes con enrutamientos estáticos y dinámicos.Incluye referencias bibliográfica

Low-Power Listening Goes Multi-Channel

Exploiting multiple radio channels for communication has been long known as a practical way to mitigate interference in wireless settings. In Wireless Sensor Networks, however, multi-channel solutions have not reached their full potential: the MAC layers included in TinyOS or the Contiki OS for example are mostly single-channel. The literature offers a number of interesting solutions, but experimental results were often too few to build confidence. We propose a practical extension of low-power listening, MiCMAC, that performs channel hopping, operates in a distributed way, and is independent of upper layers of the protocol stack. The above properties make it easy to deploy in a variety of scenarios, without any extra configuration/scheduling/channel selection hassle. We implement our solution in Contiki and evaluate it in a 97-node testbed while running a complete, out-of-the-box low-power IPv6 communication stack (UDP/RPL/6LoWPAN). Our experimental results demonstrate increased resilience to emulated WiFi interference (e.g., data yield kept above 90% when ContikiMAC drops in the 40% range). In noiseless environments, MiCMAC keeps the overhead low in comparison to ContikiMAC, achieving performance as high as 99% data yield along with sub-percent duty cycle and sub-second latency for a 1-minute inter-packet interval data collection.CALIPSORELYonI