Helen C. Leligou

Secure geographic routing in ad hoc and wireless sensor networks

Security in sensor networks is one of the most relevant research topics in resource constrained wireless devices and networks. Several attacks can be suffered in ad hoc and wireless sensor networks (WSN), which are highly susceptible to attacks, due to the limited resources of the nodes. In this paper, we propose innovative and lightweight localization techniques that allow for intrusion identification and isolation schemes and provide accurate location information. This information is used by our routing protocol which additionally incorporates a distributed trust model to prevent several routing attacks to the network. We finally evaluate our algorithms for accurate localization and for secure routing which have been implemented and tested in real ad hoc and wireless sensor networks.

Efficient Detection of Routing Attacks in Wireless Sensor Networks

A lot of effort has been spent in securing the routing procedure in wireless sensor network (WSNs) since this is accomplished in a cooperative way and is vital for the communication of the sensors with the base station which collects the sensed data. The communication over wireless links in combination with the ad hoc organization introduces vulnerabilities. Each node monitors the behaviour of its neighbours in order to check whether they behave maliciously or not. Nodes with low trustworthiness are then avoided during routing decisions which are based on location and trust information. The efficiency of the proposed approach in defending against black-hole, grey-hole and integrity attacks is evaluated using computer simulations.

Adaptive Learning Based on Affect Sensing

This paper introduces an end-to-end solution for dynamic adaptation of the learning experience for learners of different personal needs, based on their behavioural and affective reaction to the learning activities. Personal needs refer to what learner already know, what they need to learn, their intellectual and physical capacities and their learning styles.

Dynamic resource allocation in elastic optical networks

Dynamic elastic optical networks with variable bandwidth capability are investigated with respect to the effect of the flexi-grid granularity, the capacity of the connection request in optical network and network design parameters. We systematically investigate the benefits of elastic optical networking and establish the superiority of variable bandwidth elastic OFDM based networks with respect to the rigid grid counterparts under dynamic performance.

Exploiting sensing devices availability in AR/VR deployments to foster engagement

Currently, in all augmented reality (AR) or virtual reality (VR) educational experiences, the evolution of the experience (game, exercise or other) and the assessment of the user’s performance are based on her/his (re)actions which are continuously traced/sensed. In this paper, we propose the exploitation of the sensors available in the AR/VR systems to enhance the current AR/VR experiences, taking into account the users’ affect state that changes in real time. Adapting the difficulty level of the experience to the users’ affect state fosters their engagement which is a crucial issue in educational environments and prevents boredom and anxiety. The users’ cues are processed enabling dynamic user profiling. The detection of the affect state based on different sensing inputs, since diverse sensing devices exist in different AR/VR systems, is investigated, and techniques that have been undergone validation using state-of-the-art sensors are presented.

Generic platform for registration and online offering of assistance-on-demand (AoD) services in an inclusive infrastructure

An increasing percentage of the population needs assistance services for a wide range of activities related to their independent living, which can be delivered either by humans or by machines. While cloud computing and emerging ICT solutions have introduced new types of services and service delivery paradigms, it remains costly and difficult to set up and market assistance services addressing the needs of very narrow end-user groups. The current work presents the design of a novel open-source infrastructure (web-based platform) which enables diverse stakeholders to easily set up web-based assistance-on-demand platform instances. Each of these AoD instances can be used by service providers to register and offer assistance-on-demand (AoD) services for catering individual needs of persons with disabilities. In this way, narrow end-user groups can be reached and enjoy a gamut of assistance services. The AoD platform is implemented in the context of a larger Global Public Inclusive Infrastructure (GPII), which is being developed in the context of the Prosperity4All project. The functional requirements for the design of the AoD infrastructure were iteratively fine-tuned through the definition and analysis of representative use models (sets of personas and use cases). The AoD platform architecture consists of two major components: front-end (GUI) and back-end (service infrastructure). Their implementation is mainly based on the Django framework which enables a Model–Template–View (MTV) software architectural pattern with highly configurable and flexible components. The evaluation of a demonstration instance of the AoD platform with end-users identified its advantages and pointed out additional functionality needed: multi-language, multi-modality, embedded social media feeding, dedicated menu for highly flexible service, etc. The overall perceived usefulness of the specific demonstration AoD platform instance that underwent evaluation was higher than 80%. The proposed AoD platform provides a flexible and sufficiently generic web-based infrastructure for the cost-effective setup, registration and web publication of services that can accommodate a highly diverse range of assistance needs. Furthermore, it is suitable for use by a wide range of different stakeholder/user groups interested in addressing the needs of persons with disabilities or otherwise at risk of exclusion.

Evaluation of a transmission count-efficient metric for energy-aware routing in WSNs

We evaluate a routing metric, called TXPFI, which captures the expected number of frame transmissions needed for successful delivery of data in Wireless Sensor Networks (WSNs) featuring non-fully cooperative nodes and unreliable links. The study, which addresses the exploitation of the TXPFI in routing protocols of distance-vector type, assesses the impact of different network settings on the performance of the metric, compares the TXPFI with a number of routing metrics derived from the composition of primary metrics commonly used in routing protocols for WSNs, and evaluates the distribution of the transmission load to network nodes. The simulation results show that the TXPFI exhibits consistent behavior for different network parameters, outperforms the other composite metrics included in the study in terms of the overall number of transmitted frames and performs reasonably well regarding the maximum transmission load placed on the network nodes.

The implications of service virtualisation on the routing procedure in Wireless Sensor Networks

The proliferation of Wireless Sensor Networks (WSNs) has driven the design of Virtual Sensor Networks (VSNs) which decouple the physical sensor deployment from the applications running on top of it. In this concept, the Wireless Sensor Networks are no longer deployed to support a specific service but are capable of collaborating among each other (even if they belong to different administrator domains or if they comprise of heterogeneous systems) towards realizing new services and applications. The design and development of VSNs are at the focus of the VITRO project which currently develops a reference architecture [1] to enable the realization of scalable, flexible, adaptive, energy-efficient and trust-aware Virtual Sensor Network platforms. In this paper, we investigate the requirements that virtualization imposes on the routing procedure of the involved WSNs. Given that the routing protocol and the adopted routing metric affects the achieved quality of service, the support of different applications over the same WSN infrastructure mandates a)traffic handling differentiation from the routing protocol and b)proper coordination of the involved resource controller and VSN configuration management modules.