639 research outputs found

    Multiple Redundancy Constants with Trickle

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    International audienceWireless sensor network protocols very often use the Trickle algorithm to govern information dissemination. For example, the widely used IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) uses Trickle to emit control packets. We derive an analytical model of Trickle to take into account multiple redundancy constants and the common lack of synchronization among nodes. Moreover, we demonstrate message count unfairness when Trickle uses a unique global redundancy constant because nodes with less neighbors transmit more often. Consequently, we propose a heuristic algorithm that calculates a redundancy constant for each node as a function of its number of neighbors. Our calculated redundancy constants reduce unfairness among nodes by distributing more equally the number of transmitted messages in the network. Our analytical model is validated by emulations of constrained devices running the Contiki Operating System and its IPv6 networking stack. Furthermore, results very well corroborate the heuristic algorithm improvements

    Multiple Redundancy Constants with Trickle

    No full text
    International audienceWireless sensor network protocols very often use the Trickle algorithm to govern information dissemination. For example, the widely used IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL) uses Trickle to emit control packets. We derive an analytical model of Trickle to take into account multiple redundancy constants and the common lack of synchronization among nodes. Moreover, we demonstrate message count unfairness when Trickle uses a unique global redundancy constant because nodes with less neighbors transmit more often. Consequently, we propose a heuristic algorithm that calculates a redundancy constant for each node as a function of its number of neighbors. Our calculated redundancy constants reduce unfairness among nodes by distributing more equally the number of transmitted messages in the network. Our analytical model is validated by emulations of constrained devices running the Contiki Operating System and its IPv6 networking stack. Furthermore, results very well corroborate the heuristic algorithm improvements

    Building blocks for the internet of things

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    A novel routing optimization strategy based on reinforcement learning in perception layer networks

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    Wireless sensor networks have become incredibly popular due to the Internet of Things’ (IoT) rapid development. IoT routing is the basis for the efficient operation of the perception-layer network. As a popular type of machine learning, reinforcement learning techniques have gained significant attention due to their successful application in the field of network communication. In the traditional Routing Protocol for low-power and Lossy Networks (RPL) protocol, to solve the fairness of control message transmission between IoT terminals, a fair broadcast suppression mechanism, or Drizzle algorithm, is usually used, but the Drizzle algorithm cannot allocate priority. Moreover, the Drizzle algorithm keeps changing its redundant constant k value but never converges to the optimal value of k. To address this problem, this paper uses a combination based on reinforcement learning (RL) and trickle timer. This paper proposes an RL Intelligent Adaptive Trickle-Timer Algorithm (RLATT) for routing optimization of the IoT awareness layer. RLATT has triple-optimized the trickle timer algorithm. To verify the algorithm’s effectiveness, the simulation is carried out on Contiki operating system and compared with the standard trickling timer and Drizzle algorithm. Experiments show that the proposed algorithm performs better in terms of packet delivery ratio (PDR), power consumption, network convergence time, and total control cost ratio

    Identification of the Most Significant Parameter for Optimizing the Performance of RPL Routing Protocol in IoT Using Taguchi Design of Experiments

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    Internet of Things (IoT) consists of a wide variety of devices with limited power sources. Due to the adhered reason, energy consumption is considered as one of the major challenges in the IoT environment. In this research article, an attempt is made to optimize the existing Routing Protocol (RPL) towards a green technology. It focuses on finding the most significant parameter in the RPL using Taguchi Design of Experiments. It emphasizes the effects of five input factors, such as Network Size, Mobility Speed, DIO_DOUBLING, DIO_MIN_INTERVAL, and Redundancy Constant on only one output parameter Power Consumption. The findings show that DIO_MIN_INTERVAL is the leading factor that has a significant effect on the power consumption in RPL. After determining the most significant factor that affects the power consumption, measures can be taken to optimize the performance of RPL by applying some optimization techniques. COOJA simulator is used to carry out the simulations required for this research article.Comment: 12 Page

    Trickle-D: High Fairness and Low Transmission Load with Dynamic Redundancy

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    International audienceEmbedded devices of the Internet of Things form the so-called low-power and lossy networks. In these networks, nodes are constrained in terms of energy, memory and processing. Links are lossy and exhibit a transient behavior. From the point of view of energy expenditure, governing control overhead emission is crucial and is the role of the Trickle algorithm. We address Trickle's fairness problem to evenly distribute the transmission load across the network, while keeping the total message count low. First, we analytically analyze two underlying causes of unfairness in Trickle networks: desynchronization among nodes and non-uniform topologies. Based on our analysis, we propose a first algorithm whose performance and parameters we study in an emulated environment. From this feedback, we design a second algorithm TrickleD that adapts the redundancy parameter to achieve high fairness while keeping the transmission load low. We validate TrickleD in real-life conditions using a large scale experimental testbed. TrickleD requires minimal changes to Trickle, zero user input, emits 17.7% less messages than state-of-the-art and 37.2% less messages than state-of-practice, while guaranteeing high fairness across the network

    Contributions to the performance evaluation and improvement of the IPv6 routing protocol for low-power and lossy networks

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    Wireless Sensor Networks (WSNs) have become increasingly important. These networks comprise sensor and actuator nodes that enable intelligent monitoring and control applications in a wide spectrum of environments including smart cities, home automation, remote health and precision agriculture to mention a few. In certain IETF circles, networks of these characteristics are called Low Power and Lossy Networks (LLNs). Whereas most LLN protocol architectures were born without native IP support, there exists a tendency in the market towards IP convergence, since IP-based LLNs offer an open and tandardized way of connecting LLNs to the Internet, thus nabling the Internet of Things (IoT). Since most LLN configurations are multihop, and thus a routing protocol is required, the IETF created the Routing Over Low power and Lossy networks (ROLL) working group, which decided to develop a new routing protocol called IPv6 Routing Protocol for LLNs (RPL). RPL was specifically designed to meet the requirements of LLNs and is a central component of the IETF protocol suite for the IoT. Since RPL has already been deployed in millions of nodes, it is fundamental to characterize its properties, evaluate the influence of its main parameters and options on network performance, and analyze performance improvement possibilities. This PhD thesis presents the following original contributions in this field: 1. Evaluation of the influence of the main RPL parameters on the network convergence process over IEEE 802.15.4 multihop networks, in terms of network characteristics such as size and density. In addition, a mechanism that leverages an option available in RPL for accelerating network convergence has been proposed and evaluated. This study provides a guideline for configuring and selecting adequately crucial RPL parameters and mechanisms for achieving high network convergence performance, as well as a characterization of the related performance trade-offs. 2. Development of an analytical model for estimating the network convergence time of RPL in a static chain topology network of IEEE 802.15.4 nodes, in the presence of bit errors. Results show the scenarii in terms of BER and chain topology length that may dramatically degrade performance experienced by a user. The model provides a lower bound on the network convergence time for a random topology network. 3. Development of an analytical tool to estimate the number of control messages transmitted in a random topology static network which uses the Trickle algorithm (a transmission scheduling algorithm used in RPL) under steady state conditions. Results show the accuracy of the model, which can be used for both synchronous and asynchronous networks. The slight difference in performance between these two network configurations is discussed and illustrated. 4. Theoretical evaluation of the route change latency incurred by RPL when 6LoWPAN Neighbor Discovery (ND) is used. On this basis, a study on the impact of the relevant 6LoWPAN ND and RPL parameters on path availability and the trade-off between path availability and message overhead, has been carried out. 5. Development of a RPL simulator for OMNeT++ using the MiXiM framework.La importància de les Wireless Sensor Networks (WSNs) ha estat creixent significativament en els darrers anys. Aquestes xarxes comprenen node sensors i actuadors que possibiliten aplicacions de control i monitorització en un ampli ventall d'entorns, incloent les ciutats intel·ligents, automatització residencial, etc. En alguns cercles de l'IETF, aquestes xarxes són anomenades Low Power and Lossy Networks (LLNs). La majoria d'arquitectures de protocols van néixer sense suport natiu per a IP, per ha existit recentment una tendència en el mercat envers la convergència IP, ja que les LLN basades en IP ofereixen una manera oberta i estandaritzada de connectar LLNs a Internet, tot creant la Internet de les Coses. Atès que moltes configuracions de LLNsn multisalt, i per tant es requereix un protocol d'encaminament, l'IETF va crear el Routing Over Low power and Lossy networks (ROLL) working group, que va decidir dissenyar un nou protocol anomenat IPv6 Routing Protocol for LLNs (RPL). RPL va ser específicament dissenyat per complir amb els requeriments de les LLNs i és un component central de la pila de protocols de l'IETF per a la Internet de les Coses. Atès que RPL ha estat desplegat en milions de nodes, és fonamental caracteritzar les seves propietats, avaluar la influència dels seus paràmetres principals i opcions en el rendiment, i analitzar les possibilitats de millora del protocol. Aquesta tesi presenta les següents contribucions originals en aquest camp: 1. Avaluació de la influència dels principals paràmetres de RPL en el procés de convergència de la xarxa en xarxes IEEE 802.15.4, en termes de característiques com la mida i la densitat de la xarxa. A més a més, s'ha proposat i avaluat un mecanisme que utilitza una opci disponible en el RPL per a accelerar la convergència de xarxa. Aquest estudi proporciona una guia per configurar i escollir adequadament paràmetres crucials del protocol RPL per tal d'assolir una ràpida convergència de xarxa, això com una caracteritzaci dels compromisos relacionats. 2. Desenvolupament d'un model analátic per estimar el temps de convergència de xarxa de RPL en una topologia de xarxaestàtica en cadena de nodes IEEE 802.15.4, en presència d'errors. Els resultats mostren els escenaris en termes de BER i mida de la cadena que poden degradar les prestacions percebudes per l'usuari. El model proporciona una fita inferior del temps de convergència de xarxa per a una topologia aleatòria. 3. Desenvolupament d'una eina analítica per estimar el nombre de missatges de control transmesos en una xarxa de topologia aleat ria i estàtica on s'usa l'algoritme Trickle (algoritme de planificació i control de les transmissions emprat en RPL), en condicions de règim permanent. Els resultats mostren la precisió del model, que pot ser emprat en xarxes síncrones i asíncrones. La lleugera diferència de prestacions entre un escenari i l'altre és discutida i il·lustrada. 4. Avaluació teòrica del temps de canvi de ruta de RPL quan s'usa 6LoWPAN Neighbor Discovery (ND). En base a aixó , es realitza un estudi de l'impacte dels paràmetres rellevants de RPL i 6LoWPAN ND en la disponibilitat de cambi el compromís amb l'overhead de missatges. 5. Desenvolupament d'un simulador de RPL per a OMNeT++ usant el MiXiM framewor

    A Novel Adaptive and Efficient Routing Update Scheme for Low-Power Lossy Networks in IoT

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    In this paper, we introduce Drizzle, a new algorithm for maintaining routing information in the Low-power and Lossy Networks (LLNs). The aim is to address the limitations of the currently standardized routing maintenance (i.e. Trickle algorithm) in such networks. Unlike Trickle, Drizzle has an adaptive suppression mechanism that assigns the nodes different transmission probabilities based on their transmission history so to boost the fairness in the network. In addition, Drizzle removes the listen-only period presented in Trickle intervals leading to faster convergence time. Furthermore, a new scheme for setting the redundancy counter has been introduced with the goal to mitigate the negative side effect of the short-listen problem presented when removing the listen-only period and boost further the fairness in the network. The performance of the proposed algorithm is validated through extensive simulation experiments under different scenarios and operation conditions. In particular, Drizzle is compared to four routing maintenance algorithms in terms of control-plane overhead, power consumption, convergence time and packet delivery ratio (PDR) under uniform and random distributions and with lossless and lossy links. The results indicated that Drizzle reduces the control-plane overhead, power consumption and the convergence time by up to 76%, 20% and 34% respectively while maintaining approximately the same PDR rates

    Wireless Personal Area Network-Based Assistance for the Visually Impaired

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    In this dissertation, a system allowing a visually impaired person to interact with his environment is developed using modern, low-power wireless communications techniques. With recent advances in wireless sensor networks, open-source operating systems, and embedded processing technology, low-cost devices have become practically feasible as a personal notification system for impaired people. Additionally, text-to-speech capabilities can now be employed without special application specific integrated circuits (ASICs), allowing low-cost, general-purpose processors to fill a niche that once required expensive semiconductors. The system takes advantage of 802.15.4 and media access control (MAC) protocols offered by the open source operating system TinyOS. Important characteristics of these new standards that make them ideal for interface with humans are short range, low- power, and open-source software. To facilitate research and development in use and integration of such devices, we developed a hardware platform to allow exploration of possible future network architectures with multiple options for interfacing with the user. Our Visually Impaired Notification System (VINS) allows unprecedented awareness of the environment and has been simulated with multiple nodes using a modification of the TinyOS Dissemination protocol. This dissertation outlines the hardware platform, demonstration of a working prototype, and simulations of how the system would work in its intended environment. We envision this system being used as a testbed allowing further research of other communications and message-delivery techniques. Additionally, the research has contributed directly to the TinyOS project and offered new insight into power management in embedded systems. Finally, through the research effort we were able to contribute to the open source movement and have produced software in four languages used in three countries with over 1500 downloads
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