Bernd-Ludwig Wenning

Environmental monitoring aware routing: making environmental sensor networks more robust

Wireless Sensor Networks (WSNs) have a broad application range in the area of monitoring and surveillance tasks. Among these tasks, disaster detection or prevention in environmental scenarios is one typical application for WSN. Disasters may for example be forest fires, volcano outbreaks or flood disasters. Here, the monitored events have the potential to destroy the sensor devices themselves. This has implications for the network lifetime, performance and robustness. While a fairly large body of work addressing routing in WSNs exists, little attention has been paid to the aspect of node failures caused by the sensed phenomena themselves. This paper presents a proactive routing method that is aware of the node’s destruction threat and adapts the routes accordingly, before node failure results in broken routes, delay and power consuming route re-discovery. The performance of the presented routing scheme is evaluated and compared to OLSR based routing in the same scenario.

Environmental Monitoring Aware Routing in Wireless Sensor Networks

Bernd-Ludwig Wenning and Dirk Pesch and Andreas Timm-Giel and CarmelitaGo¨rgAbstract Wireless Sensor Networks(WSNs) are designedfor many monitoringandsurveillancetasks.AtypicalscenariocategoryistheuseofWSNs fordisaster detec-tion in environmental scenarios. In disasters such as forest r es, volcano outbreaksor o od disasters, the monitored events have the potential to destroy the sensor de-vices themselves. This has implications for the network lifetime, performance androbustness. While a fairly large body of work addressing routing in WSNs exists,little attention has been paid to the aspect of node failurescaused by the sensedphenomenon itself. This contribution presents a routing method that is aware ofthe nodes destruction threat and adapts the routes accordingly, before node failureresults in broken routes,delay and power consumingroutere-discovery.The perfor-mance of the presented routing scheme is evaluated and compared to AODV basedrouting in the same scenario.

Logistic applications with wireless sensor networks

Wireless Sensor Networks have been deployed for environmental monitoring, home automation, and advanced metering application fields among others. Only few examples of monitoring cargo transports by Wireless Sensor Networks have been reported on. The authors have deployed mobile Wireless Sensor Networks in a cargo container on a trans-atlantic cargo vessel as well as on a lorry to monitor the transport conditions inside the container. This submission reports on the experiences gained from those particular deployments and the open research issues for mobile Wireless Sensor Networks for logistics.

A model of Wireless Sensor Networks using context-awareness in logistic applications

Although Wireless Sensor Networks (WSNn) are designed to operate with low power consumption, much of the research in this field focuses on improving the efficiency of resource usage. In many scenarios, WSNs are configured to monitor and transmit the observed data periodically. This can lead to duplication of traffic in the network if most of the sensed data does not change over time under normal conditions. In this paper, a flexible context-aware model of Wireless Sensor Networks (WSNs) is presented for use in logistic contexts to reduce that unnecessary information. By being aware of contexts, WSNs know which information is significant to transmit. Generated traffic load and energy efficiency are considered to illustrate the advantages of the proposed context-aware model.

Agent-Based and Discrete Event Simulation of Autonomous Logistic Processes

The current trends and recent changes in logistics lead to new, complex and partially conflicting requirements on logistic planning and control systems. Currently available strategies and methodologies do not address these new requirements sufficiently. The concept of autonomous logistic processes intends to overcome these drawbacks together with latest information and communication technologies. Their analysis and design is subject to simulation studies. Two simulation systems for the analysis of autonomy in logistics with an agent-based and a discrete event approach are presented. Both systems are designed and suitable for different aspects of autonomous logistic processes.

Scalability of dense wireless lighting control networks

In modern lighting systems, the introduction of wirelessly controlled LED light sources leads to very dense wireless lighting networks. Current approaches for control message transmission are based on broadcasting messages among many luminaires. However, adequate communication performance - in particular, sufficiently low latency and synchronicity - is difficult to ensure in such networks, especially if the network is part of a wireless building management system and carries not only low-latency broadcast messages but also collects data from sensors. This article describes the challenge of dense wireless lighting control networks. In particular, it discusses the underlying mechanisms and refers to current wireless sensor network solutions in which scalability is relevant.

Autonomous Control by Means of Distributed Routing

In current logistic practices, routing and assignment of transport orders to vehicles are done centrally by a dispatching system and/or a human dispatcher. Here, the dispatching problem is generally of static nature and is solved either by the use of heuristics, e.g. evolutionary algorithms or Tabu search, or by applying “rules” that are gained from experience, when done by a human dispatcher.

Spectrum sharing between IEEE 802.16 and IEEE 802.11 based wireless networks

Due to the high scarcity and high costs of radio spectrum, more and more radio services are occupying unlicensed bands for their operation. Due to this, there is a high risk of destructive interference which degrades the performance and fails to support Quality of Service (QoS) for systems operating in these bands. IEEE 802.11 based wireless networks are already operating in unlicensed band. A new competitor for unlicensed bands is the IEEE 802.16 based wireless metropolitan area network. Therefore, spectrum sharing between coexisting competing wireless systems like 802.11 and 802.16 is an upcoming challenge. To understand the characteristics of interference in such a heterogeneous scenario, an analysis of possible interference is presented and the performance of the legacy systems is evaluated. Then a spectrum sharing concept is proposed which can generally be applied to both systems. In this paper, the proposed concept is adapted for coexisting 802.16 and 802.11e based systems, which is an extention of 802.11. In this case, the 802.11e Hybrid Coordination Function (HCF) Controlled Channel Access (HCCA) is extended to provide a protocol for airtime sharing. Simulation results are presented showing that the proposed algorithm provides excellent improvement of system performance in the context of capacity and channel utilization compared to the case without applying any spectrum sharing method.

Statistical Analysis of Contact Patterns between Human-Carried Mobile Devices

In this paper, we focus on analyzing the impact of human-to-human contact patterns on opportunistic communication in Pocket Switched Networks (PSNs). We take advantage of statistical methods to consider the distributions of two different types of inter-contact time as well as the number of contacts between human-carried mobile devices. Different from the results from recent studies, we present empirical evidence that power law with exponential cutoff characterizes all three distributions of interest better than other possible long-tail distributions. We further show that each of the investigated distributions has a finite mean value. Having a finite mean value is of importance for each distribution, as it facilitates the design of distributed community detection algorithms as well as social-based forwarding algorithms. Finally, we make the recommendation to exploit the average number of contacts as a threshold for each device to determine their friend-set, which is a precondition for some distributed community detection algorithms.

WiSeCoMaSys: A tool for data collection and management of Wireless Sensor Networks

Currently, many specialized tools for monitoring and control of sensor networks are existing and being used separately. In this paper, an architecture of a component-based tool, named WiSeCoMaSys, is presented to integrate data monitoring from sensor networks, visualization, measurements and network management in a unique system. WiSeCoMaSys helps developers to debug their network deployments easily in many scenarios. Meanwhile, users can change a variety of parameters at any layer of the sensor node architecture to respond to network changes or optimize the performance. Moreover, statistic functionalities are also integrated in this tool to measure and evaluate the real time status of the entire network. With a completely integrated architecture, WiSeCoMaSys is a promising tool to interact with sensor networks visually in many sensing applications.