Stavros Stavrou

Open University of Cyprus · Faculty of Pure and Applied Sciences

Ransomware is considered among the top threats that organizations have to face, and one that is not expected to go away anytime soon. Cyber criminals have turned ransomware into a profitable business by targeting environments in which they can maximize the attack’s impact and their profits. The Maritime domain is a lucrative environment as it suppo...

In recent years, attackers have shifted their attention in the Maritime domain, exploiting vulnerabilities of Maritime IT/OT systems and human resources, and impacting the situational picture onboard the ships and/or at shore infrastructures. Therefore, developing human skills and systems’ detection capabilities in the Maritime domain are a critica...

Big Data and Artificial Intelligence are new technologies to improve indoor localization. It focuses on the use of machine learning probabilistic algorithms to extract, model and analyse live and historical signal data obtained from several sources. In this respect, the data generated by 5G network and the Internet of Things is quintessential for p...

This paper presents a Wi-Fi Evil Twin, Man in the Middle attack (MiTM), which utilizes channel switch announcement (802.11h). The proposed technique examines and demonstrates through measurements the feasibility to perform a successful MiTM attack, when the target receives a lower received signal strength from the rogue access point (AP), compared...

Cyber Ranges exist to enable hands on training within realistic ICT infrastructures in a sandboxed environment, to investigate attack and defense strategies and to assess the resilience of the infrastructures. To fully exploit their capabilities one has to have access to multi domain exercises, which may combine ICT, naval, electrical grid, telecom...

The densification of modern wireless networks into a dense ecosystem of small cells imposes challenges for the reliable service and high quality of experience of its users as it can result into severe intercell interference, especially for users scattered on the cell edges. Joint Transmission Coordinated Multipoint (JT-CoMP) is a technique that can...

In the near future, the fifth-generation wireless technology is expected to be rolled out, offering low latency, high bandwidth and multiple antennas deployed in a single access point. This ecosystem will help further enhance various location-based scenarios such as assets tracking in smart factories, precise smart management of hydroponic indoor v...

With the introduction of diverse technology paradigms in next-generation cellular and vehicular networks, design and structural complexity are skyrocketing. The beyond-5G use cases such as mobile broadband, 5G-V2X and UAV communications require support for ultra-low latency and high throughput and reliability with limited operational complexity and...

Planning and deploying a functional large scale Wireless Sensor Network (WSN) or a Network of Internet of Things (IoTs) is a challenging task, especially in complex urban environments. The typical complex urban environment distorts the RF signal from nodes due to multipath and as a result the connectivity of the network could be problematic. The ne...

This research work investigates how RSS information fusion from a single, multi-antenna access point (AP) can be used to perform device localization in indoor RSS based localization systems. The proposed approach demonstrates that different RSS values can be obtained by carefully modifying each AP antenna orientation and polarization, allowing the...

Deploying a functional large scale Wireless Sensor Net-works (WSNs) or Network of Internet of Things (IoTs), re-mains a big challenge, mainly due the difficulties in introducing realistic physical layer conditions in network layer simulators. In this demo we demonstrate the interconnection of a commercial physical layer simulator, TruNET wireless,w...

Planning and deploying a functional large scale Wireless Sensor Network (WSN) or a Network of Internet of Things (IoTs) is a challenging task, especially in complex urban environments. A main network design bottleneck is the existence and/or correct usage of appropriate cross layer simulators that can generate realistic results for the scenario of...

Open-source intelligence (OSINT) is intelligence collected from publicly available sources to meet specific intelligence requirements. This paper proposes a new method to localise and profile the movement of social network users through OSINT and machine learning techniques. Analysis of obtained OSINT social networks posts data from targeted users,...

Security issues of typical Voice over Internet Protocol (VoIP) applications are studied in this paper; in particular, the open source Linphone application is being used as a case study. An experimental analysis indicates that protecting signalling data with the TLS protocol, which unfortunately is not always the default option, is needed to allevia...

Self-organizing network (SON) is seen as playing a pivotal role towards reducing the management costs of networks for the exposure of 5G and beyond 5G networks. SON is capable of collecting information from the network, so as to perform self- configuration, self-optimization, self-healing, etc., so as to reduce the operation cost through less human...

Indoor user localization and tracking are instrumental to a broad range of services and applications in the Internet of Things (IoT) and particularly in Body Sensor Networks (BSN) and Ambient Assisted Living (AAL) scenarios. Due to the widespread availability of IEEE 802.11, many localization platforms have been proposed, based on the Wi-Fi Receive...

Video content providers put stringent requirements on the quality assessment methods realized on their services. They need to be accurate, real-time, adaptable to new content, and scalable as the video set grows. In this letter, we introduce a novel automated and computationally efficient video assessment method. It enables accurate real-time (onli...

Many Transmission Power Control (TPC) algorithms have been proposed in the past, yet the conditions under which they are evaluated do not always reflect typical Internet-of-Things (IoT) scenarios. IoT networks consist of several source nodes transmitting data simultaneously, possibly along multiple hops. Link failures are highly frequent, causing t...

Satellite images can provide valuable information about the presented urban landscape scenes to remote sensing and telecommunication applications. Obtaining information from satellite images is difficult since all the objects and their surroundings are presented with feature complexity. The shadows cast by buildings in urban scenes can be processed...

Obtaining the segmentation of building footprints from satellite images is a complex process since building areas and their surroundings are presented with various colour intensity values and complex features. Active contour region-based segmentation methods can be used to establish the corresponding boundary of building structures. Typically, thes...

Provision of accurate location information is an important task in the Internet of Things (IoT) applications and scenarios. This need has boosted the research and development of fingerprint based, indoor localization systems, since GPS information is not available in indoor environments. Performance evaluation of such systems and their related loca...

Location aware applications are constantly under development. By using an Indoor Location System (ILS), a user can localize himself, plan an indoor route and destination, or receive useful information and services in malls, airports, shopping centers, etc. To this purpose, various signal strength or timing based localization methods exist, each one...

This study proposes a unifying framework for m-Health video communication systems that provides for the joint optimization of video quality, bitrate demands, and encoding time. The framework is video modality and infrastructure independent and facilitates adaptation to the best available encoding mode that satisfies underlying technology and applic...

Tracking wireless devices in an indoor environment using off-the-shelf equipment is a challenging task. Typical time-based off-the-shelf indoor localization methods tend to collect a large number of packet timestamps and subsequently apply statistical analysis in order to localize the target. However, the kinematic characteristics of the target and...

Location aware applications are constantly under development. By using an Indoor Location System (ILS), a user can localize himself, plan an indoor route and destination, or receive useful information and services in malls, airports, shopping centers, etc. To this purpose, various signal strength or timing based localization methods exist, each one...

Time-based localization methods can be especially useful in dynamic environments, where the usefulness of Received Signal Strength (RSS) fingerprint based methods can be limited. Typical `off the shelf' 802.11 network packet time-based methods, tend to collect a large number of packets and apply statistical analysis in order to localize a user. Thi...

This paper investigates how positioning accuracy is affected in map-aided positioning systems, when a user's typical route is described by different probability distribution types. Probability distributions are introduced in an effort to better explain any reasonable route deviations from the user's center line of movement. The user route is assume...

The objective of this research work is to investigate and demonstrate potential accuracy improvements in the RSS indoor positioning process, by introducing directional antennas in the radio network infrastructure. The position and orientation is selected in such a way as to decrease the correlation levels of the Received Signal Strength (RSS) finge...

The objective of this work is to investigate potential accuracy improvements in the fingerprint-based indoor Wi-Fi positioning processes, by imposing map-constraints into the positioning algorithms in the form of a-priori probabilistic knowledge. In our approach, we propose the introduction of a Route Probability Factor (RPF), which reflects the po...

This work proposes a novel methodology for the evaluation of indoor positioning systems, by adopting a binomial distribution approach during the evaluation process. The positioning accuracy achieved by any Real Time Localisation System (RTLS) is affected by various critical factors, such as the network infrastructure, the positioning algorithms imp...

One of the main advantages when comparing time over signal strength localization methods, is that the former do not require the creation of fingerprint databases. On the other hand, the majority of time based methods require some sort of clock synchronization due to the drifting of the local clocks. This paper presents an innovative time-based loca...

Obtaining segmentations of buildings from satellite images for telecommunication applications is a complex process due to the fact that satellite or aerial images are complicated scenes. The algorithm presented in this work uses level set Chan-Vese formulation, to establish the corresponding boundaries of the buildings. Level set segmentation tends...

This deliverable reports on the work performed in COGEU T7.3 and T7.4. It demonstrates the COGEU system through trials in Munich and Slovakian scenarios (Bratislava and Banska Bystrica areas) to validate previous laboratory testing.

A system for anchor-less self-positioning and simultaneous 2D estimation of rectangular room dimensions is proposed. The system is based on narrowband transceiver capable of simultaneous transmission and reception. The transmission is generated at omnidirectional antenna, while eight sectorized antennas with 45deg apertures in horizontal are used f...

This paper regards the application of ray tracing (RT) tools for indoor localization techniques. The paper presents two possible applications of RT tools in that context. The first is the train/construction of fingerprints databases in order to complement or/and replace laborious measurement campaigns. The second application is the modeling of loca...

This work proposes the use of 3D Ray Tracing (RT) to construct radiomaps for WLAN Received Signal Strength (RSS) fingerprint-based positioning, in conjunction with calibration techniques to tackle with the problem using different devices. In addition to the fact that RSS data collection might be a tedious and time-consuming process, the measured ra...

This paper presents an overview of current research investigations within the WHERE-2 Project with respect to location-dependent information extraction and how this information can be used towards the benefit of positioning. It is split into two main sections; the first one relies on non-radio means such as inertial sensors and prior knowledge abou...

We study the use of 3D Ray Tracing (RT) to construct radiomaps for WLAN Received Signal Strength (RSS) fingerprint-based positioning, in conjunction with calibration techniques to make the overall process device-independent. RSS data collection might be a tedious and time-consuming process and also the measured radiomap accuracy and applicability i...

The rapid advent of different wireless technologies has posed several new challenges and requirements which current architectures are not able to appropriately deal with. The growing presence of heterogeneous access networks, together with the increasing demands from the end-users, require a re-thinking of current access selection algorithms and ap...

The combined testbeds that are designed, set up and evaluated in the COGEU project for the testing of coexistence of various communications systems in the TV White Spaces, are described including the test signals that are available from different sources.

A system for simultaneous 2D estimation of rectangular room and transceiver localization is proposed. The system is based on two radio transceivers, both capable of full duplex operations (simultaneous transmission and reception). This property enables measurements of channel impulse response (CIR) at the same place the signal is transmitted (gener...

This work examines the penetration loss suffered through periodic wall structures currently used by the building industry. A full-wave method, the modal transmission-line (MTL), is used to investigate the radio-propagation behavior through a periodic building structure under the most general condition of oblique incidence (three-dimensional inciden...

This paper proposes the deployment of frequency selective surfaces (FSS) in indoor wireless environments and investigates their effect on radio wave propagation. FSS can be deployed to selectively confine radio propagation in indoor areas, by artificially increasing the radio transmission loss naturally caused by building walls. FSS can also be use...

This deliverable reports on the work performed in COGEU task T7.1. It describes the COGEU demonstrator setup and defines the scenarios, showcases and performance metrics for COGEU system validation. The demonstration will focus on the critical functionalities of the COGEU dynamic secondary market of TV white spaces. Further steps in the integration...

A hybrid model is presented to study the radio wave propagation through periodic building structures for site-specific outdoor-to-indoor propagation. This hybrid model is based on combining ray-tracing and rigorous coupled wave analysis (RCWA) method, which is used to obtain the transmission properties of periodic building structures in the case of...

The phase of complex correlation is exploited to provide estimation of the azimuth arrival angle of ultra wideband multipath signals. Regarding the cluster model for uniform linear arrays, spatial correlation between antenna elements plays an important role in the analytical stage. Performance of this estimation is validated by using frequency-doma...

In this paper we present the potential advantages in terms of capacity improvements of Distributed antenna systems (DAS); also known as Distributed-MIMO (D-MIMO) environments when compared against conventional MIMO and/or SISO systems. The spatial channel parameters are calculated using deterministic modeling techniques such as Ray Tracing. © 2012...

Energy is a critical resource in the design of wireless networks since wireless devices are usually powered by batteries. Without any new approaches for energy saving, 4G mobile users will relentlessly be searching for power outlets rather than network access, and becoming once again bound to a single location. To avoid the so called 4G “energy tra...

This study presents a statistical power delay profile (PDP) model for the evaluation and design of ultra wideband (UWB) off-body communication systems. The analysis is based on extensive real-body measurements carried out in the frequency range between 3.5 and 6.5 GHz. Due to the dependence of the radio propagation channel on the body region (i.e....

A statistical model for ultrawideband (UWB) off-body communication channels is proposed. The presented results are the outcome of extensive real-body measurements carried out in the frequency range between 3.5 and 6.5 GHz in typical indoor environments. The signal power gain is modeled by a log-linear dual-breakpoint model, the parameters of which...

Quantification of distortion effects on UWB system performances in terms of positioning error is analysed in this research. UWB multipath distorted channels are simulated in each frequency subband, over 2-11 GHz. Its characteristics are modelled corresponding to multipath clusters along the propagation paths. The classification of clusters and phys...

This deliverable presents a literature survey of localisation in communication networks. In a first part, use of communication networks for location estimation is presented. Two families of methods do exist: fingerprinting and geometrical techniques. Cooperative positioning is one possible enhancement. In a second part, use of location information...

The modified aspects for simulating UWB multipath channels are presented in this paper. Pulse distortion mechanisms based on the geometric optics and the geometric theory of diffraction are specifically generated combing with the spatio-temporal characteristics of multipath clusters based on 3times3 planar array systems. In each particular scenario...

This deliverable presents a literature survey of localisation in communication networks. In a first part, use of communication networks for location estimation is presented. Two families of methods do exist: fingerprinting and geometrical techniques. Cooperative positioning is one possible enhancement. In a second part, use of location information...

A novel, multi-slope dual breakpoint model for predicting path-loss in ultra-wideband (UWB) off-body communication channels, is proposed. This model is based on real-body measurements, carried out in the frequency range between 3.5GHz-6.5GHz, in an anechoic chamber. New parameters that describe this specific propagation environment are presented an...

This paper presents a measurement-based statistical channel model for describing UWB off-body propagation and is valid for the frequency range from 3.5 to 6.5 GHz. This model is expressed with respect to both radial and azimuth coordinates, and is physically motivated by creeping wave propagation around smooth convex surfaces, such as the human bod...

A modified simulation of ultra-wideband (UWB) multipath channels, combined with cluster classification and physics-based pulse distortion mechanisms, is proposed in this letter. Spatiotemporal characteristics of multipath clusters are specifically generated based on 3 times 3 planar array systems with regard to scenario types and are simulated over...

Demonstrated is the potential benefit in terms of MIMO capacity gain after deploying frequency selective surfaces (FSS) in indoor environments where MIMO systems are installed and operated. The idea is that the presence of strong multipath components at every receiving element in an indoor environment would make the channel more Rayleigh, which can...