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Item type:Publication, Access status: without files , Investigation & Mitigation of the Energy Efficiency Impact of Node Resets in RPL(2021-04); ; ; ; Dependability is a keyword within the recent discussion about the operation of Wireless Sensor Network (WSN) as a vital part of the ever-growing Internet of Things (IoT). However, while focusing on, e.g., reliable routing it is often neglected that the energy supply is an important factor to enable dependable WSN, and thus IoT operation. Using the example of the Routing Protocol for Low power and Lossy Networks (RPL) we will show that a high operational capability is often at the expense of energy resources. Nevertheless, we will also show that this issue can be mitigated. While the resilience of RPL has been verified in a plethora of existing evaluations, the impact of simple node resets on the energy efficiency has not been investigated so far. However, resets may happen for a variety of reasons which are stated in this work as well. Thus, in the first part of this paper we examine the energy costs of resets in a RPL network. We show that such temporary node failures can have a serious impact on the network's total energy usage depending on failure location and topology. As resets are common in real WSNs this work reveals an important weakness of RPL which can even be exploited for attacks. To mitigate this issue, in the second part of this paper we propose a hardening of RPL by maintaining a backup of the RPL state information in a non-volatile memory. Improvements as well as limitations of this approach and a mechanism for a seamless recovery are discussed and described in detail. Finally, the effectiveness and the characteristics of the proposed approach to harden RPL are evaluated extensively.Publicationtype: Journal Article35 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , REAPer - adaptive micro-source energy-harvester for wireless sensor nodesEnergy Harvesting is a solution for continued operation of WSNs without depending on batteries. This paper introduces REAPer, an adaptive energy harvester for microsources that can be configured and monitored by the supplied WSN node. We combine REAPer with an IdealVolting capable sensor node that can fully exploit the monitoring and control capabilities of REAPer. The efficiency and overhead of the REAPer harvester is analysed. A field test evaluates REAPer with different power sources.Publicationtype: Conference Paper75 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Energy efficiency impact of transient node failures when using RPLThe Routing Protocol for Low power and Lossy Networks (RPL) is a wide-spread, flexible routing protocol specifically designed for energy-constrained networks such as Wireless Sensor Networks (WSNs). The resilience of RPL has been verified in several existing evaluations, but how a simple node reset can impact the energy efficiency has not been investigated so far. Thus, in this paper we examine the energy costs of transient node failures in a RPL network. We show that such temporary node failures can have a significant impact on the network's total energy usage. As transient node failures are common in WSNs this work reveals an important weakness of RPL which can even be exploited for attacks.Publicationtype: Conference Paper28 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Dynamic sample rate adaptation for long-term IoT sensing applicationsIn long-term sensing applications data patterns can vary significantly over time. Often a multitude of sensors are used to measure different types of environmental conditions. Considering such variations it is hard to select a predefined sample rate that guarantees both, high data quality and energy efficiency. Hence, this paper presents a dynamic sample rate adaptation that strikes a balance offering optimal energy efficiency while maintaining high data quality. Based on the general concept of Bollinger Bands, a metric is derived that solely depends on the trend of the measured data itself. A real world measurement in the area of smart farming is used to show the effectiveness of this approach.Publicationtype: Conference Paper35 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Undervolting in real world WSN applications: a long-term study(IEEE, 2016-08-08); ; ; ; The fault-tolerant character of WSN protocols and applications that do not assume completely reliable systems legitimize undervolting - a highly efficient energy management technique where the supply voltage is set below the minimum specifications. As has been shown in earlier work, by using the reliable IdealVolting undervolting scheme the lifetime of WSN applications can be increased significantly while keeping the node in a safe state even under rough environmental conditions. To show the usability of undervolting in a real world WSN deployment, we performed a long-term study of IdealVolting in a Smart Farming application. All measurements were performed on a generic outdoor testbed for WSNs (PotatoNet) which is also presented within this paper. We collected a long-term dataset of a WSN running for one farming season on a potato field to compare the reliability and performance characteristics of IdealVolting against a regular powered WSN.Publicationtype: Conference Paper29 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Paint it black - Increase WSN energy efficiency with the right housing(Association for Computing Machinery (ACM), 2015-11-01); ; ; It is a well-known fact that Wireless Sensor Networks (WSNs) that are exposed to real environmental conditions suffer from harsh temperatures. Yet, the temperature does not only have negative impact as the energy efficiency of processing units benefits from higher temperatures. The minimal voltage for correct operation of CMOS circuits is bounded by the temperature. Thus, temperature-dependent undervolting schemes for WSN nodes have been proposed in the past to extend the network lifetime. However, not much thought has been given into directly inuencing the most relevant factor: Temperature. In this work we look at the inuence of various WSN housings onto the temperature profile of WSN nodes and quantify the energy saving potential of choosing the right housing.Publicationtype: Conference Paper63 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Demo: PotatoNet - Robust outdoor testbed for WSNs: Experiment like on your desk. Outside(Association for Computing Machinery (ACM), 2015-09-11); ; ; ; We present PotatoNet, an outdoor testbed for Wireless Sensor Networks (WSNs). Its primary focus is robustness, reliability and flexibility. PotatoNet is designed to operate without on-site maintenance for extended periods of time. It can withstand heat, dust and rain and has already been tested running outside for several months.Publicationtype: Conference Paper25