Panagiotis Trakadas

Trust management in wireless sensor networks

SUMMARY The range of applications of wireless sensor networks is so wide that it tends to invade our every day life. In the future, a sensor network will survey our health, our home, the roads we follow, the office or the industry we work in or even the aircrafts we use, in an attempt to enhance our safety. However, the wireless sensor networks themselves are prone to security attacks. The list of security attacks, although already very long, continues to augment impeding the expansion of these networks. The trust management schemes consist of a powerful tool for the detection of unexpected node behaviours (either faulty or malicious). Once misbehaving nodes are detected, their neighbours can use this information to avoid cooperating with them, either for data forwarding, data aggregation or any other cooperative function. A variety of trust models which follow different directions regarding the distribution of measurement functionality, the monitored behaviours and the way measurements are used to calculate/define the node’s trustworthiness has been presented in the literature. In this paper, we survey trust models in an attempt to explore the interplay among the implementation requirements, the resource consumption and the achieved security. Our goal is to draw guidelines for the design of deployable trust model designs with respect to the available node and network capabilities and application peculiarities. Copyright

A Novel Trust-Aware Geographical Routing Scheme for Wireless Sensor Networks

AbstractWireless sensor networks are vulnerable to a wide set of security attacks, including those targeting the routing protocol functionality. The applicability of legacy security solutions is disputable (if not infeasible), due to severe restrictions in node and network resources. Although confidentiality, integrity and authentication measures assist in preventing specific types of attacks, they come at high cost and, in most cases, cannot shield against routing attacks. To face this problem, we propose a secure routing protocol which adopts the geographical routing principle to cope with the network dimensions, and relies on a distributed trust model for the detection and avoidance of malicious neighbours. A novel function which adaptively weights location, trust and energy information drives the routing decisions, allowing for shifting emphasis from security to path optimality. The proposed trust model relies on both direct and indirect observations to derive the trustworthiness of each neighboring node, while it is capable of defending against an increased set of routing attacks including attacks targeting the indirect trust management scheme. Extensive simulation results reveal the advantages of the proposed model.

Design of primary and composite routing metrics for RPL-compliant Wireless Sensor Networks

The diversity of applications that current and emerging Wireless Sensor Networks (WSNs) are called to support imposes different requirements on the underlying network with respect to delay and loss, while at the same time the WSN imposes its own intricacies. The satisfaction of these requirements highly depends on the metric upon which the forwarding routes are decided. In this view, the IETF ROLL group has proposed the RPL routing protocol, which can flexibly work on various routing metrics, as long as they hold specific properties. The system implementer/user is free to decide whether to use one or multiple routing metrics, as well as the way these metrics can be combined. In this paper, we provide ways to quantify the routing metrics so that they can be combined in an additive or lexical manner. We use extensive simulation results to evaluate the impact of several routing metrics on the achieved performance.

Combining trust with location information for routing in wireless sensor networks

As the applications of wireless sensor networks proliferate, the efficiency in supporting large sensor networks and offering security guarantees becomes an important requirement in the design of the relevant networking protocols. Geographical routing has been proven to efficiently cope with large network dimensions while trust management schemes have been shown to assist in defending against routing attacks. Once trust information is available for all network nodes, the routing decisions can take it into account, i.e. routing can be based on both location and trust attributes. In this paper, we investigate different ways to incorporate trust in location-based routing schemes and we propose a novel way of balancing trust and location information. Computer simulations show that the proposed routing rule exhibits excellent performance in terms of delivery ratio, latency time and path optimality. Copyright

Evaluating routing metric composition approaches for QoS differentiation in low power and lossy networks

The use of Wireless Sensor Networks (WSN) in a wide variety of application domains has been intensively pursued lately while Future Internet designers consider WSN as a network architecture paradigm that provides abundant real-life real-time information which can be exploited to enhance the user experience. The wealth of applications running on WSNs imposes different Quality of Service requirements on the underlying network with respect to delay, reliability and loss. At the same time, WSNs present intricacies such as limited energy, node and network resources. To meet the application’s requirements while respecting the characteristics and limitations of the WSN, appropriate routing metrics have to be adopted by the routing protocol. These metrics can be primary (e.g. expected transmission count) to capture a specific effect (e.g. link reliability) and achieve a specific goal (e.g. low number of retransmissions to economize resources) or composite (e.g. combining latency with remaining energy) to satisfy different applications needs and WSNs requirements (e.g. low latency and energy consumption at the same time). In this paper, (a) we specify primary routing metrics and ways to combine them into composite routing metrics, (b) we prove (based on the routing algebra formalism) that these metrics can be utilized in such a way that the routing protocol converges to optimal paths in a loop-free manner and (c) we apply the proposed approach to the RPL protocol specified by the ROLL group of IETF for such low power and lossy link networks to quantify the achieved performance through extensive computer simulations.

Theoretical investigation of the field conditions in a vibrating reverberation chamber with an unstirred component

In this paper, we examine the use of a vibrating reverberation chamber in which an equipment under test (EUT) is directly illuminated by a source antenna. A three-dimensional theoretical model, based on a simplified ray tracing method has been applied on a reverberation chamber whose dimensions were varied. The field distribution together with the field homogeneity was investigated, introducing the Rice distribution due to the presence of the line-of-sight component between the antenna and the EUT.

A novel flexible trust management system for heterogeneous wireless sensor networks

Security has been recognised as a key issue for the expansion of wireless sensor network applications. To defend against the wide set of security attacks, legacy security solutions are not applicable due to the very limited memory and processing resources of the sensor nodes as well as due to the reason that sensor networks are required to operate in an autonomous infrastructureless manner. Trust management schemes consist a powerful tool for the detection of unexpected node behaviours (either faulty or malicious). Once misbehaving nodes are detected, their neighbours can use these information to avoid cooperating with them either for data forwarding, data aggregation or any other cooperative function. We propose a novel trust management system based on both direct and indirect trust information, which allows for fast detection of a wide set of attacks, including those addressing the reputation exchange scheme, while energy awareness is also incorporated in our approach.

RPL modeling in J-Sim platform

Recently, Routing Protocol for Low Power and Lossy Networks (RPL) has been proposed by IETF ROLL WG in order to cope with Low Power and Lossy Networks (LLN) requirements implied by different application domains. In this paper, we present RPL modeling in J-Sim simulation environment, providing a complete simulation framework for performance evaluation as well as experimentation on open issues, such as the support of multiple instances and the definition of routing strategies based on the composition of several metrics.

PERFORMANCE OF A SIX-BEAM SWITCHED PARASITIC PLANAR ARRAY UNDER ONE PATH RAYLEIGH FADING ENVIRONMENT

The technology of adaptive antennas is rapidly growing during the last years. It is true that switched beam antennas,the simplest type of smart antennas,may provide substantial benefits when implemented in a cellular mobile telephony system. The performance of a six-beam switched parasitic planar array,in terms of bit error rate (BER) measurement,is presented in this paper. The switched parasitic planar array is designed with the aid of genetic algorithms method. The antenna system is evaluated in a radio environment where interfering signals are present. The results obtained from the simulation are compared with respect to the ones when an omni directional antenna is used instead of the switched beam array, revealing that the performance of such a telecommunication system can be improved.

Efficient routing in PAN and sensor networks

Routing in both PANs and sensor networks can be significantly improved, if each node knows the network topology. However, this leads to high signalling overhead and power loss, given the frequent network topology changes. In order to compromise between efficient routing and communications /power limitations, various algorithms have been proposed. In this paper, a selection of algorithms proposed for ad-hoc networks are classified according to their relevancy and efficiency, when applied to PANs and sensor networks.