Evaluation of RPL’s Single Metric Objective Functions

In this paper, we evaluate the performance of RPL (IPv6 Routing Protocol for Low Power and Lossy Networks) based on the Objective Function being used to construct the Destination Oriented Directed Acyclic Graph (DODAG). Using the Cooja simulator, we compared Objective Function Zero (OF0) with the Minimum Rank with Hysteresis Objective Function (MRHOF) in terms of average power consumption, packet loss ratio, and average end-to-end latency. Our study shows that RPL performs better in terms of packet loss ratio and average endto-end latency when MRHOF is used as an objective function. However, the average power consumption is noticeably higher compared to OF0

Impact of RPL objective functions on energy consumption in Ipv6 based wireless sensor networks

International audienceWith the arrival of the internet of things concept, a new vision of wireless sensor networks has been adopted allowing them to be addressed with ipv6 addresses, thus forming 6LowPAN networks. It is categorized as a new technology being developed and improved. This causes issues about the networks performance to create the communication path and collecting data. Therefore, IETF has proposed an IPv6 based routing protocol with low cost and power constraints RPL that builds a Destination Oriented Directed Acyclic Graph (DODAG) based on a set of metrics and constraints via a specific Objective Functions (OFs). This objective function selects the best parents and construct the routes. Our research is focus on performance analysis of two objective functions that are Minimum Rank with Hysteresis Objective Function (MRHOF) and Objective Function Zero (OFO) in a small area under a large scenarios and topologies. This comparison is focused on energy consumption of the network in the given scenrios to distinguish which objective function is the most optimal to guarantee long life expectancy of the sensor networks especially in static environment

Assessing the Impact of Mobile Attackers on RPL-based Internet of Things

The Internet of Things (IoT) is becoming ubiquitous in our daily life. IoT networks that are made up of devices low power, low memory, and low computing capability appears in many applications such as healthcare, home, agriculture. IPv6 Routing Protocol for Low Power and Lossy Network (RPL) has become a standardized routing protocol for such low-power and lossy networks in IoT. RPL establishes the best routes between devices according to the requirements of the application, which is achieved by the Objective Function (OF). Even though some security mechanisms are defined for external attackers in its RFC, RPL is vulnerable to attacks coming from inside. Moreover, the same attacks could has different impacts on networks with different OFs. Therefore, an analysis of such attacks becomes important in order to develop suitable security solutions for RPL. This study analyze RPL-specific attacks on networks using RPL's default OFs, namely Objective Function Zero (OF0) and the Minimum Rank with Hysteresis Objective Function (MRHOF). Moreover, mobile attackers could affect more nodes in a network due to their mobility. While the security solutions proposed in the literature assume that the network is static, this study takes into account mobile attackers.Comment: 11 pages,3 figures, Journa

A Test Bed for Evaluating the Performance of IoT Networks

The use of smaller, personal IoT networks has increased over the past several years. These devices demand a lot of resources but only have limited access. To establish and sustain a flexible network connection, 6LoWPAN with RPL protocol is commonly used. While RPL provides a low-cost solution for connection, it lacks load balancing mechanisms. Improvements in OF load balancing can be implemented to strengthen network stability. This paper proposes a test bed configuration to show the toll of frequent parent switching on 6LoWPAN. Contiki’s RPL 6LoWPAN software runs on STM32 Nucleo microcontrollers with expansion boards for this test bed. The configuration tests frequency of parent changes and packet loss to demonstrate network instability of different RPL OFs. Tests on MRHOF for RPL were executed to confirm the working configuration. Results, with troubleshooting and improvements, show a working bed. The laid-out configuration provides a means for testing network stability in IoT networks

Optimizing RPL performance based on the selection of best route between child and root node using E-MHOF method

IETF has proposed the routing protocol for low power and lossy networks (RPL) for IOT as view as light weight routing protocol. In RPL, the objective function (OF) is used to select the best route between child and root node. Several researches have been conducted in order to, enhance OF according to number parameters such as number of hops, remaining energy and expected number of transmissions (ETX), without a consideration to other challenges such as congestion node problem and latency. So, to overcome these challenges a new technique called “Enhance-Minimum Rank with Hysteresis Objective Function (MHOF)” is proposed in this paper, to select the ideal path between the child and root node. The technique is consisted of three layers: parent selection layer in which parent is selected based on three parameters (ETX, RSSI and nodes’ residual energy), path selection layer in which the best route is chosen according to the minimum of (average ETX value) and maximum of (average remaining energy value) of all nodes in the selected route. The last layer is child node minimization, which utilized to solve the congestion node energy problem by using two parameters (RSSI reference and threshold value). The proposed method has been implemented and evaluated by using Cooja simulator software. The simulation results have shown that selected path with E-MHOF is increased the network lifetime and reduced latency in comparison with MHOF

On Link Estimation in Dense RPL Deployments

The Internet of Things vision foresees billions of devices to connect the physical world to the digital world. Sensing applications such as structural health monitoring, surveillance or smart buildings employ multi-hop wireless networks with high density to attain sufficient area coverage. Such applications need networking stacks and routing protocols that can scale with network size and density while remaining energy-efficient and lightweight. To this end, the IETF RoLL working group has designed the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL). This paper discusses the problems of link quality estimation and neighbor management policies when it comes to handling high densities. We implement and evaluate different neighbor management policies and link probing techniques in Contiki’s RPL implementation. We report on our experience with a 100-node testbed with average 40-degree density. We show the sensitivity of high density routing with respect to cache sizes and routing metric initialization. Finally, we devise guidelines for design and implementation of density-scalable routing protocols

Bifurcation discovery tool

Motivation: Biochemical networks often yield interesting behavior such as switching, oscillation and chaotic dynamics. This article describes a tool that is capable of searching for bifurcation points in arbitrary ODE-based reaction networks by directing the user to regions in the parameter space, where such interesting dynamical behavior can be observed. Results: We have implemented a genetic algorithm that searches for Hopf bifurcations, turning points and bistable switches. The software is implemented as a Systems Biology Workbench (SBW) enabled module and accepts the standard SBML model format. The interface permits a user to choose the parameters to be searched, admissible parameter ranges, and the nature of the bifurcation to be sought. The tool will return the parameter values for the model for which the particular behavior is observed. Availability: The software, tutorial manual and test models are available for download at the following website: http:/www.sys-bio.org/ under the bifurcation link. The software is an open source and licensed under BSD

Analysis of the solar cycle and core rotation using 15 years of Mark-I observations:1984-1999. I. The solar cycle

High quality observations of the low-degree acoustic modes (p-modes) exist for almost two complete solar cycles using the solar spectrophotometer Mark-I, located at the Observatorio del Teide (Tenerife, Spain) and operating now as part of the Birmingham Solar Oscillations Network (BiSON). We have performed a Fourier analysis of 30 calibrated time-series of one year duration covering a total period of 15 years between 1984 and 1999. Applying different techniques to the resulting power spectra, we study the signature of the solar activity changes on the low-degree p-modes. We show that the variation of the central frequencies and the total velocity power (TVP) changes. A new method of simultaneous fit is developed and a special effort has been made to study the frequency-dependence of the frequency shift. The results confirm a variation of the central frequencies of acoustic modes of about 450 nHz, peak-to-peak, on average for low degree modes between 2.5 and 3.7 mHz. The TVP is anti-correlated with the common activity indices with a decrease of about 20% between the minimum and the maximum of solar cycle 22. The results are compared with those obtained for intermediate degrees, using the LOWL data. The frequency shift is found to increase with the degree with a weak l-dependence similar to that of the inverse mode mass. This verifies earlier suggestions that near surface effects are predominant.Comment: Accepted by A&A October 3 200

Carbon Dioxide Enhanced Oil Recovery

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