Security Trade-offs in Cyber Physical Systems: A Case Study Survey on Implantable Medical Devices

The new culture of networked systems that offer everywhere accessible services has given rise to various types of security trade-offs. In fact, with the evolution of physical systems that keep getting integrated with cyber frameworks, cyber threats have far more critical effects as they get reflected on the physical environment. As a result, the issue of security of cyber physical systems requires a special holistic treatment. In this paper, we study the trade-off between security, safety and availability in such systems and demonstrate these concepts on implantable medical devices as a case study. We discuss the challenges and constraints associated with securing such systems and focus on the trade-off between security measures required for blocking unauthorized access to the device, and the safety of the patient in emergency situations where such measures must be dropped to allow access. We analyze the up to date proposed solutions and discuss their strengths and limitations

Synoptic analysis techniques for intrusion detection in wireless networks

Current system administrators are missing intrusion alerts hidden by large numbers of false positives. Rather than accumulation more data to identify true alerts, we propose an intrusion detection tool that e?ectively uses select data to provide a picture of ?network health?. Our hypothesis is that by utilizing the data available at both the node and cooperative network levels we can create a synoptic picture of the network providing indications of many intrusions or other network issues. Our major contribution is to provide a revolutionary way to analyze node and network data for patterns, dependence, and e?ects that indicate network issues. We collect node and network data, combine and manipulate it, and tease out information about the state of the network. We present a method based on utilizing the number of packets sent, number of packets received, node reliability, route reliability, and entropy to develop a synoptic picture of the network health in the presence of a sinkhole and a HELLO Flood attacker. This method conserves network throughput and node energy by requiring no additional control messages to be sent between the nodes unless an attacker is suspected. We intend to show that, although the concept of an intrusion detection system is not revolutionary, the method in which we analyze the data for clues about network intrusion and performance is highly innovative

Low-power wide-area networks : design goals, architecture, suitability to use cases and research challenges

Previous survey articles on Low-Powered Wide-Area Networks (LPWANs) lack a systematic analysis of the design goals of LPWAN and the design decisions adopted by various commercially available and emerging LPWAN technologies, and no study has analysed how their design decisions impact their ability to meet design goals. Assessing a technology's ability to meet design goals is essential in determining suitable technologies for a given application. To address these gaps, we have analysed six prominent design goals and identified the design decisions used to meet each goal in the eight LPWAN technologies, ranging from technical consideration to business model, and determined which specific technique in a design decision will help meet each goal to the greatest extent. System architecture and specifications are presented for those LPWAN solutions, and their ability to meet each design goal is evaluated. We outline seventeen use cases across twelve domains that require large low power network infrastructure and prioritise each design goal's importance to those applications as Low, Moderate, or High. Using these priorities and each technology's suitability for meeting design goals, we suggest appropriate LPWAN technologies for each use case. Finally, a number of research challenges are presented for current and future technologies. © 2013 IEEE

The evolution of electronic warfare equipment and techniques in the USA, 1901 to 1945

This work describes the evolution cf electronic warfare equipment and techniques in the USA, from the first instance of radio jamming in that country in 1901 until the end of World War II in 1945. It begins with a review of early work on telegraph, radio and radar systems throughout the world, and countermeasures used during trials or in combat prior to World War II. Immediately after the USA ertered the conflict in 1941, the Radio Research Laboratory was set up near Boston to develop radio countermeasures equipment for the US armed forces. The organisation rapidly outgrew the capacity of a angle laboratory and in October 1942 Division 15 of the National Defense Research Committee was formed, to co-ordinate US work on countermeasures. The activities of RRL and Division 15 are described in detail, using cortemporary records and accounts from participants. Radar jammers developed by Divison 15 were first used in action in July 1943 during the invason of Sicily, and went on to play important roles in support amphibious landings and strategic bombing operations in the European and Pacific theatres of operations. The jamming devices and tactics employed, the enemy attempts to develop counter-countermeasures and the US moves to counter these counters are all described in detail. Conclusions are drawn on the effectiveness of the various types of jamming, based on post-war interrogation of German and Japanese serving officers and technical personnel. Appendices give technical details of the countermeasures devices produced in the USA during World War II, and the development of radar and radar countermeasures in Germany and Japan

ORBITAL ANGULAR MOMENTUM ORTHOGONALITY-BASED CROSSTALK REDUCTION: THEORY AND EXPERIMENT

Full duplex communication systems allow a single channel to be used for simultaneous two-way communication, increasing spectral efficiency. However, full duplex communication systems suffer from the issue of self-interference between local transmitter and receiver antennas. Analog subtraction and signal processing methods have previously been used to reduce this problem. This dissertation proposes the use of waves carrying orbital angular momentum (OAM) to mitigate the problem of self-interference by offering a means of additional isolation between local antennas. Orbital angular momentum has been widely studied both in the photonics and radio domain. The theoretically infinite orthogonal states of an OAM signal make it highly desirable in the field of communication. The application of OAM in a full duplex system, may be the answer to the problem of self-interference. This dissertation shows how the use of OAM waves may create an additional isolation between local antennas in a full duplex system. Motivated by the promise that OAM orthogonality holds, this dissertation explores the crosstalk reduction achieved through OAM. One of the main contributions of this dissertation is to provide insight into the nature of the effect. It motivates OAM orthogonality as a direction of research for use in future full duplex systems. The effect of OAM on crosstalk must be studied experimentally and theoretically. To this effect, a patch array antenna was designed using the High Frequency Simulation Software (HFSS), to generate OAM beams. The designed antennas are fabricated and characterized. This dissertation discusses the experiments carried out to determine the amount of crosstalk reduction achieved due to the OAM nature of the signal transmitted. The impact of the change in distance between the local transmitter and receiver antennas on crosstalk is also studied. The results obtained are verified through theoretical analysis using simulations in HFSS. This dissertation reports a maximum theoretical crosstalk reduction of 3.6dB, and a crosstalk reduction of 2.6 dB realized experimentally. Building on these results, a compact, more practical antenna configuration was designed. This nested design yields more than 60dB crosstalk reduction and provides for a more elegant system realization. The dissertation includes the design of a parabolic dish antenna to build a complete system, which is also studied in this dissertation. The symmetry of the nested antenna configuration allows for analytic theoretical study which is included herein. The study mathematically proves the orthogonality of OAM modes, and the isolation between two antennas with different OAM modes. A similar study is simulated in HFSS using coaxial based loop antennas, and the crosstalk in the nested design is investigated. The design offers a crosstalk isolation of more than 90dB, and further affirms the mathematical analysis. This dissertation provides a detailed analysis of the isolation offered by OAM orthogonality in local antennas which can be useful in a full duplex system. The work consists of practical, simulated, and mathematical investigation, and considers various antenna configurations and designs. Additionally, it presents and analyses a design for a full duplex system

Localisation in wireless sensor networks for disaster recovery and rescuing in built environments

A thesis submitted to the University of Bedfordshire in partial fulfilment of the requirements for the degree of Doctor of PhilosophyProgress in micro-electromechanical systems (MEMS) and radio frequency (RF) technology has fostered the development of wireless sensor networks (WSNs). Different from traditional networks, WSNs are data-centric, self-configuring and self-healing. Although WSNs have been successfully applied in built environments (e.g. security and services in smart homes), their applications and benefits have not been fully explored in areas such as disaster recovery and rescuing. There are issues related to self-localisation as well as practical constraints to be taken into account. The current state-of-the art communication technologies used in disaster scenarios are challenged by various limitations (e.g. the uncertainty of RSS). Localisation in WSNs (location sensing) is a challenging problem, especially in disaster environments and there is a need for technological developments in order to cater to disaster conditions. This research seeks to design and develop novel localisation algorithms using WSNs to overcome the limitations in existing techniques. A novel probabilistic fuzzy logic based range-free localisation algorithm (PFRL) is devised to solve localisation problems for WSNs. Simulation results show that the proposed algorithm performs better than other range free localisation algorithms (namely DVhop localisation, Centroid localisation and Amorphous localisation) in terms of localisation accuracy by 15-30% with various numbers of anchors and degrees of radio propagation irregularity. In disaster scenarios, for example, if WSNs are applied to sense fire hazards in building, wireless sensor nodes will be equipped on different floors. To this end, PFRL has been extended to solve sensor localisation problems in 3D space. Computational results show that the 3D localisation algorithm provides better localisation accuracy when varying the system parameters with different communication/deployment models. PFRL is further developed by applying dynamic distance measurement updates among the moving sensors in a disaster environment. Simulation results indicate that the new method scales very well

Development and characterization of a standardized docking system for small spacecraft

Since the first mating manoeuvre in space, performed in 1966, many different docking mechanisms were developed, mainly for large manned spacecraft. The few systems recently conceived for small satellites have never been verified in space nor scaled to CubeSat size. In the near future, small spacecraft docking procedures could acquire great importance due to the need to share resources between clusters of low-weight and low-cost vehicles: in fact, small spacecraft market is rapidly growing, focusing on commercial low risk application, low budget scientific and educational missions. In this context, this document presents a novel docking mechanism to provide small spacecraft with the ability to join and separate in space, to realize multi-body platforms able to rearrange, be repaired or updated, thus overcoming the actual on board limitations of single small-scale satellites. As for now, the few proposed docking ports present (1) simple probe-drogue interfaces, unable to dock with same-gender ports, or (2) androgynous geometries, that can overcome that problem, but usually employing complex and non-axis-symmetric latches to perform the docking manoeuvre, that would demand robust and stringent navigation and control systems. The proposed solution overcomes the aforementioned drawbacks, using a semi-androgynous shape-shifting mechanism that actuating one interface changes the port into a “drogue" configuration, letting the other port penetrate it and closing around to create a solid joint. The mechanism design through the requirement definition and a trade-off between different concepts is presented, followed by the analysis of the dynamic behaviour of the selected solution, with particular attention to two aspects, i.e. the loads transmitted between the mating ports and the alignment tolerances requested to perform successful docking manoeuvres. Such analysis led to the definition of an instrumented prototype to verify the solution through simple validation tests, which demonstrated the mechanism operations and defined the alignment ranges, that lie in the range of +- 15 mm and up to 6 degrees. Last, a comparison with SPHERES UDP is presented, as part of the activities performed during a visit period at MIT Space Systems Laboratory

Analysis, Implementation and Considerations for Liquid Crystals as a Reconfigurable Antennas Solution (LiCRAS) for Space

The space industry has predominantly relied on high gain reflector dish antenna apertures for performing communications, but is constantly investing in phase array antenna concepts to provide increased signal flexibility at reduced system costs in terms of finances and system resources. The problem with traditional phased arrays remains the significantly greater program cost and complexity added to the satellite by integrating arrays of antenna elements with dedicated amplifier and phase shifters to perform adaptive beam forming. Liquid Crystal Reflectarrays (LiCRas) offer some of the electrical beam forming capability of a phased array system with the component and design complexity in lines with a traditional reflector antenna aperture but without the risks associated with mechanical steering systems. The final solution is believed to be a hybrid approach that performs in between the boundaries set by the two current disparate approaches. Practical reflectarrays have been developed since the 90s as a means to control reflection of incident radiation off a flat structure that is electrically curved based on radiating elements and their reflection characteristics with tailored element phase delay. In the last decade several methods have been proposed to enable tunable reflectarrays where the electrical shape of the reflector can be steered by controlling the resonating properties of the elements on the reflector using a DC bias. These approaches range from complex fast switching MEMS and ferroelectric devices, to more robust but slower chemical changes. The aim of this work is to investigate the feasibility of a molecular transition approach in the form of liquid crystals which change permittivity based on the electrical field they are subjected to. In this work, particular attention will be paid to the impact of space environment on liquid crystal reflectarray materials and reflector architectures. Of particular interest are the effects on performance induced by the temperature extremes of space and the electromagnetic particle environment. These two items tend to drive much of the research and development for various space technologies and based on these physical influences, assertions can be made toward the space worthiness of such a material approach and can layout future R&D needs to make certain LC RF devices feasible for space use. Moreover, in this work the performance metrics of such a technology will be addressed along with methods of construction from a space perspective where specific design considerations must be made based on the extreme environment that a typical space asset must endure.\u2

Distributed anomaly detection models for industrial wireless sensor networks

Wireless Sensor Networks (WSNs) are firmly established as an integral technology that enables automation and control through pervasive monitoring for many industrial applications. These range from environmental applications and healthcare applications to major industrial monitoring applications such as infrastructure and structural monitoring. The key features that are common to such applications can be noted as involving large amounts of data, consisting of dynamic observation environments, non-homogeneous data distributions with evolving patterns and sensing functionality leading to data-driven control. Also in most industrial applications a major requirement is to have near real-time decision support. Accordingly there is a vital need to have a secure continuous and reliable sensing mechanism in integrated WSNs where integrity of the data is assured. However, in practice WSNs are vulnerable to different security attacks, faults and malfunction due to inherent resource constraints, openly commoditised wireless technologies employed and naive modes of implementation. Misbehaviour resulting from such threats manifest as anomalies in the sensed data streams in critically compromising the systems. Therefore, it is vital that effective techniques are introduced in accurately detecting anomalies and assuring the integrity of the data. This research focuses on investigating such models for large scale industrial wireless sensor networks. Focusing on achieving an anomaly detection framework that is adaptable and scalable, a hierarchical data partitioning approach with fuzzy data modelling is introduced first. In this model unsupervised data partitioning is performed in a distributed manner by adapting fuzzy c-means clustering in an incremental model over a hierarchical node topology. It is found that non-parametric and non-probabilistic determination of anomalies can be done by evaluating the fuzzy membership scores and inter-cluster distances adaptively over the node hierarchy. Considering heterogeneous data distributions with evolving patterns, a granular anomaly detection model that uses an entropy criterion to dynamically partition the data is proposed next. This successfully overcomes the issue of determining the proper number of expected clusters in a dynamic manner. In this approach the data is partitioned on to different cohesive regions using cumulative point-wise entropy directly. The effect of differential density distributions when relying on an entropy criterion is mitigated by introducing an average relative density measure to segregate isolated outliers prior to the partitioning. The combination of these two factors is shown to be significantly successful in determining anomalies adaptively in a fully dynamic manner. The need for near real-time anomaly evaluation is focused next on this thesis. Building upon the entropy based data partitioning model that is also proposed, a Point-of-View (PoV) entropy evaluation model is developed next. This employs an incremental data processing model as opposed to batch-wise data processing. Three unique points-of-view are introduced as the reference points over which point-wise entropy is computed in evaluating its relative change as the data streams evolve. Overall this thesis proposes efficient unsupervised anomaly detection models that employ distributed in-network data processing for accurate determination of anomalies. The resource constrained environment is taken in to account in each of the models with innovations made to achieve non-parametric and non-probabilistic detection