Christian Haas

A wireless sensor network for border surveillance

We will demonstrate a wireless sensor network system for the surveillance of critical areas and properties -- e.g. borders. The system consists of up to 10 sensor nodes that monitor a small border area. The protocols we show focus on detecting trespassers across a predefined area and reporting the detection to a gateway node securely. There, the trespassers path will be graphically diplayed on a border map. The demonstration features secure protocols for the detection of trespassers, node failure and network partitioning, along with a duty cycle protocol to ensure network longevity. All information pertaining to relevant events in the network or border area will be graphically displayed on a gateway computer.

Realistic simulation of energy consumption in wireless sensor networks

In this paper we analyze whether energy consumption in a wireless sensor network (WSN) can be evaluated realistically and accurately using the Avrora simulation tool. For this purpose, results from a reference experiment using SANDbed, a WSN testbed with focus on energy measurements, and Avrora, a wireless sensor network simulation tool, are compared. In this experiment, we found a difference in total energy consumption up to 20% between simulation and reality. The analysis revealed several issues that influenced the accuracy of Avrora simulations. We thus adapted Avrora for dealing with the identified issues. A concluding evaluation shows that the improved Avrora+ reduces the difference between simulation and testbed to <5%.

Energy evaluations in wireless sensor networks: a reality check

The development of energy-efficient applications and protocols is one of the most important issues in Wireless Sensor Networks (WSN). However, most publications up to now avoid time consuming realistic energy evaluations and oversimplify their evaluation with regard to energy-efficiency. This work aims at lowering the barrier for realistic energy evaluations. We focus on a generic application that simply transmits one packet using TinyOS Low Power Listening (LPL), which we evaluate using the WSN testbed SANDbed. Our results disprove some intuitive expectations. For example, we show that transmitting packets with a large payload can be cheaper in terms of energy consumption than a small payload. As packet transmission is part of almost any WSN application, the results shown are important to many WSN protocol evaluations. As an addition, we contribute our lessons learned by discussing the most important challenges and pitfalls we faced during our evaluation.

Evaluating energy-efficiency of hardware-based security mechanisms

Security in Wireless Sensor Networks (WSNs) is an omnipresent topic. In many application scenarios, like the surveillance of critical areas or infrastructures, security mechanisms have to be used to build reliable and secure applications. Up to now, most of the used cryptographic algorithms have been implemented in software despite the resource constraints in terms of processing power, memory and energy. In the past few years, the usage of special hardware accelerated security modules has been proposed as a viable alternative to software implementations. However, the energy-efficiency has not yet been evaluated in-depth. In this paper, we analyze the VaultIC420 security module and present an evaluation of its energy-efficiency. We compare the performance and energy-efficiency of the hardware module to common software implementations like TinyECC. For the energy measurements, we use IRIS sensor nodes in the SANDbed testbed at the Karlsruhe Institute of Technology. Our evaluation shows, that the VaultIC420 can save up to 76% of energy using different MAC layer protocols. It also shows, that the current draw of the VaultIC420 requires a duty-cycling mechanisms to achieve any savings compared to the software implementation.

Software-based smart factory networking

Abstract This paper describes a framework for software-based networking in smart factories (SF) that enables them to easily adapt the communication network to changing requirements. Similar to cloud-based systems, such SFs could be seen as production clusters that could be rented and configured as needed. The SF network utilizes software-defined networking (SDN) combined with network functions virtualization (NFV) in order to achieve the required flexibility. This paper presents and discusses our vision of a network architecture for SFs based on SDN and network virtualization in order to support smart services especially for Industrie 4.0. Despite the fact that the technology is nowadays not yet ready for deployment in todays manufacturing networks, we present a framework for software-defined factory networks and discuss possible challenges and benefits.

Energy-efficiency of concast communication in Wireless Sensor Networks

In monitoring scenarios, Wireless Sensor Networks commonly transmit measurements from a large number of sensor nodes to a central data sink. This communication pattern is known as concast. Different approaches have been proposed to improve the energy-efficiency of concast and thus the lifetime of the WSN. However, energy-efficiency evaluations that are close to reality are missing. This paper systematically analyzes the influence of aggregation strategies, tree topologies, and different MAC protocols on the energy-efficiency of concast communication. We implement a sample concast application and analyze it using the AVRORA + simulator to gain realistic evaluation results. Our results disproof some common assumptions. We show that aggregation improves energy-efficiency only in a few cases and can even degrade it. Instead, MAC protocol and parametrization have a higher impact on energy-efficiency.

Evaluating the energy-efficiency of the Rich Uncle key exchange protocol in WSNs

This paper evaluates the energy consumption of three key exchange protocols Rich Uncle, (EC)DH-(EC)DSA and Kerberos. It aims at determining which protocol can exchange keys between two sensor nodes in the most energy-efficient way. To realistically compare the energy consumption, the protocols are implemented in TinyOS on the MICAz platform and simulated using the Avrora+ simulator. The key exchange protocols are evaluated in combination with four common duty-cycling MAC protocols. We show, that the Kerberos protocol is the key exchange protocol with the least overall energy consumption per key exchange, mostly due to the extremely cheap cryptographic operations. When compared with the ECDH-ECDSA key exchange protocol, this outweighs the additional message overhead needed for communication with the trusted third party in Kerberos. Rich Uncle fails to beat ECDH-ECDSA, even after off-loading the more expensive cryptographic operations to the Rich Uncle super nodes. Furthermore, we show that there are cross-layer effects caused by the MAC protocols that highly influence the overall energy consumption of the key exchange protocols.

Security in Border Control and Area Monitoring

Abstract Area monitoring is one of the most popular application scenarios for wireless sensor networks. The pure task of distributed object tracking has often been investigated, but little attention has been given to secure object tracking. This article contains a security analysis and an attacker model for the scenario of secure border surveillance and describes security mechanisms and protocols as well as a realization of such a system. Zusammenfassung Ein weitverbreitetes Einsatzgebiet für drahtlose Sensornetze ist die Grenz- und Liegenschaftsüberwachung. Es existieren verschiedene Arbeiten zur Detektion und Lokalisierung von Eindringlingen, jedoch wurden in bisherigen Arbeiten Aspekte der Informationssicherheit nur wenig untersucht. Dieser Artikel beinhaltet eine Sicherheitsanalyse und eine Angreiferbeschreibung für diesen Anwendungsbereich und stellt Sicherheitsmechanismen und Protokolle sowie die Realisierung eines solchen Systems vor.