SDR for Physical Layer Authentication

Wireless networks and devices are easy and useful solutions nowadays, regardless of the context in which they are implemented. However, it is in the broadcast nature of wireless networks that some vulnerabilities arise. To protect against these vulnerabilities, encryp- tion and authentication methods are commonly used. However, such methods come at the expense of their own complexity, requiring high enough computational power to solve, and introducing latency. To try to reduce the complexity of the conventional ways of user authentication, this work has studied mechanisms to implement reliable authentication at the physical layer, analyzing the various devices signal characteristics. To achieve this analysis, the GNU Radio platform was used to process incoming signals and extract the necessary features. Given the open source nature of GNU Radio, this provides a customiz- able and low-cost solution to signal processing and feature extraction. This research uses the GNU Radio to implement a feature extraction solution and constructs a feature vector with size 1 × 95. This thesis studies the extracted features of eleven IEEE 802.15.4 devices in regards to their separability and proposes a solution for feature reduction. The feature vectors are passed through a Random Forest and a Deep Neural Network (DNN) classifier, achieving accuracies as high as 99% for short distance communication.Redes e dispositivos sem fio são implementações úteis e fáceis de realizar atualmente, independentemente do contexto em que são desenvolvidas. No entanto, é na natureza de difusão destas redes que surgem algumas vulnerabilidades. Métodos de criptografia e autenticação são usualmente utilizados para proteger contra essas vulnerabilidades. No entanto, esses métodos apresentam uma complexidade inerente, necessitando de poder computacional e introduzindo latência. Para tentar reduzir a complexidade das formas convencionais de autenticação de utilizadores das redes, esta dissertação estudou me- canismos para implementar uma autenticação fiável na camada física, analisando as ca- racterísticas dos sinais dos diversos dispositivos que utilizam a rede. Para realizar esta análise, a plataforma GNU Radio foi utilizada para processar sinais recebidos e extrair as características necessárias. Dada a natureza de código aberto do GNU Radio, é possível desenvolver uma solução customizável e de baixo custo. Esta dissertação utiliza o GNU Radio para implementar uma solução de extração de características e constrói um vetor de características de tamanho 1×95. Esta dissertação estuda as características extraídas de onze dispositivos IEEE 802.15.4 em relação à separabilidade destas e propõe uma solução para redução de características. Os vetores são passados por um classificador de Florestas Aleatórias (Random Forest) e um classificador de Redes Neurais Profundas, atingindo precisões de até 99% para comunicação a curta distância

Towards low power radio localisation

This work investigates the use of super-resolution algorithms for precision localisation and long-term tracking of small subjects, like rodents. An overview is given of a variety of techniques for positioning in use today, namely received signal strength, time of arrival, time difference of arrival and direction of arrival (DoA). Based on the analysis, it is concluded that the direction finding signal subspace based techniques are most appropriate for the purposes of our system. The details of the software defined radio (SDR) antenna array testbed development, build, characterisation and performance evaluation are presented. The results of direction finding experiments in the screened anechoic chamber emulating open-space propagation are discussed. It is shown that such testbed is capable of locating sources in the vicinity of the array with high precision. It can estimate the DoAs of more simultaneously working transmitters than antennas in the array, by employing spread spectrum techniques, and readily accommodates very low power sources. Overall constraints on the system are such that the operational range must be around 50 – 100 m. The transmitter must be small both volumetrically and in terms of weight. It also has to be operational over an extended period of around 1 year. The implications of these are that very small antennas and batteries must be used, which are usually accompanied by very low transmission efficiencies and tiny capacities, respectively. Based on the above, the use of ultra-low power oscillator transmitters, as first cut prototypes of the tag, is proposed. It is shown that the Clapp, Colpitts, Pierce and Cross-coupled architectures are adequate. A thorough analysis of these topologies is provided with full details of tag and antenna co-design. Finally the performance of these architectures is evaluated through simulations with respect to power output, overall efficiency and phase noise.Open Acces

Airborne laser sensors and integrated systems

The underlying principles and technologies enabling the design and operation of airborne laser sensors are introduced and a detailed review of state-of-the-art avionic systems for civil and military applications is presented. Airborne lasers including Light Detection and Ranging (LIDAR), Laser Range Finders (LRF), and Laser Weapon Systems (LWS) are extensively used today and new promising technologies are being explored. Most laser systems are active devices that operate in a manner very similar to microwave radars but at much higher frequencies (e.g., LIDAR and LRF). Other devices (e.g., laser target designators and beam-riders) are used to precisely direct Laser Guided Weapons (LGW) against ground targets. The integration of both functions is often encountered in modern military avionics navigation-attack systems. The beneficial effects of airborne lasers including the use of smaller components and remarkable angular resolution have resulted in a host of manned and unmanned aircraft applications. On the other hand, laser sensors performance are much more sensitive to the vagaries of the atmosphere and are thus generally restricted to shorter ranges than microwave systems. Hence it is of paramount importance to analyse the performance of laser sensors and systems in various weather and environmental conditions. Additionally, it is important to define airborne laser safety criteria, since several systems currently in service operate in the near infrared with considerable risk for the naked human eye. Therefore, appropriate methods for predicting and evaluating the performance of infrared laser sensors/systems are presented, taking into account laser safety issues. For aircraft experimental activities with laser systems, it is essential to define test requirements taking into account the specific conditions for operational employment of the systems in the intended scenarios and to verify the performance in realistic environments at the test ranges. To support the development of such requirements, useful guidelines are provided for test and evaluation of airborne laser systems including laboratory, ground and flight test activities

Radio frequency fingerprint identification for Internet of Things: A survey

Radio frequency fingerprint (RFF) identification is a promising technique for identifying Internet of Things (IoT) devices. This paper presents a comprehensive survey on RFF identification, which covers various aspects ranging from related definitions to details of each stage in the identification process, namely signal preprocessing, RFF feature extraction, further processing, and RFF identification. Specifically, three main steps of preprocessing are summarized, including carrier frequency offset estimation, noise elimination, and channel cancellation. Besides, three kinds of RFFs are categorized, comprising I/Q signal-based, parameter-based, and transformation-based features. Meanwhile, feature fusion and feature dimension reduction are elaborated as two main further processing methods. Furthermore, a novel framework is established from the perspective of closed set and open set problems, and the related state-of-the-art methodologies are investigated, including approaches based on traditional machine learning, deep learning, and generative models. Additionally, we highlight the challenges faced by RFF identification and point out future research trends in this field

Sensors and Systems for Indoor Positioning

This reprint is a reprint of the articles that appeared in Sensors' (MDPI) Special Issue on “Sensors and Systems for Indoor Positioning". The published original contributions focused on systems and technologies to enable indoor applications

Transceiver architectures and sub-mW fast frequency-hopping synthesizers for ultra-low power WSNs

Wireless sensor networks (WSN) have the potential to become the third wireless revolution after wireless voice networks in the 80s and wireless data networks in the late 90s. This revolution will finally connect together the physical world of the human and the virtual world of the electronic devices. Though in the recent years large progress in power consumption reduction has been made in the wireless arena in order to increase the battery life, this is still not enough to achieve a wide adoption of this technology. Indeed, while nowadays consumers are used to charge batteries in laptops, mobile phones and other high-tech products, this operation becomes infeasible when scaled up to large industrial, enterprise or home networks composed of thousands of wireless nodes. Wireless sensor networks come as a new way to connect electronic equipments reducing, in this way, the costs associated with the installation and maintenance of large wired networks. To accomplish this task, it is necessary to reduce the energy consumption of the wireless node to a point where energy harvesting becomes feasible and the node energy autonomy exceeds the life time of the wireless node itself. This thesis focuses on the radio design, which is the backbone of any wireless node. A common approach to radio design for WSNs is to start from a very simple radio (like an RFID) adding more functionalities up to the point in which the power budget is reached. In this way, the robustness of the wireless link is traded off for power reducing the range of applications that can draw benefit form a WSN. In this thesis, we propose a novel approach to the radio design for WSNs. We started from a proven architecture like Bluetooth, and progressively we removed all the functionalities that are not required for WSNs. The robustness of the wireless link is guaranteed by using a fast frequency hopping spread spectrum technique while the power budget is achieved by optimizing the radio architecture and the frequency hopping synthesizer Two different radio architectures and a novel fast frequency hopping synthesizer are proposed that cover the large space of applications for WSNs. The two architectures make use of the peculiarities of each scenario and, together with a novel fast frequency hopping synthesizer, proved that spread spectrum techniques can be used also in severely power constrained scenarios like WSNs. This solution opens a new window toward a radio design, which ultimately trades off flexibility, rather than robustness, for power consumption. In this way, we broadened the range of applications for WSNs to areas in which security and reliability of the communication link are mandatory

Selected Papers from the 5th International Electronic Conference on Sensors and Applications

This Special Issue comprises selected papers from the proceedings of the 5th International Electronic Conference on Sensors and Applications, held on 15–30 November 2018, on sciforum.net, an online platform for hosting scholarly e-conferences and discussion groups. In this 5th edition of the electronic conference, contributors were invited to provide papers and presentations from the field of sensors and applications at large, resulting in a wide variety of excellent submissions and topic areas. Papers which attracted the most interest on the web or that provided a particularly innovative contribution were selected for publication in this collection. These peer-reviewed papers are published with the aim of rapid and wide dissemination of research results, developments, and applications. We hope this conference series will grow rapidly in the future and become recognized as a new way and venue by which to (electronically) present new developments related to the field of sensors and their applications

Development of an acoustic measurement system of the Modulus of Elasticity in trees, logs and boards

The objective of this Bachelor’s Thesis is to develop a portable electronic device capable of quantifying the stiffness of the wood of standing trees, logs and boards using non-destructive testing (NDT) by means of acoustic wave analysis. As an indicator of stiffness, the Modulus of Elasticity (MOE) is used, a standard figure in the industry. This way, wood from forestry can be characterized and classified for different purposes. This Thesis is part of LIFE Wood For Future, a project of the University of Granada (UGR) financed by the European Union’s LIFE programme. LIFE Wood For Future aims to recover the cultivation of poplar (populus sp.) in the Vega de Granada, by proving the quality of its wood through innovative structural bioproducts. Recovering the poplar groves of Granada would have great benefits for the Metropolitan Area: creation of local and sustainable jobs, improvement of biodiversity, and increase in the absorption of carbon dioxide in the long term, helping to reduce the endemic air pollution of Granada. This Final Degree Project has been developed in collaboration with the ADIME research group of the Higher Technical School of Building Engineering (ETSIE) and the aerospace electronics group GranaSat of the UGR. The goal of the developed device, named Tree Inspection Kit (or TIK), is to be an innovative, portable and easy-to-use tool for non-destructive diagnosis and classification of wood by measuring its MOE. TIK is equipped with the necessary electronics to quantify the Time of Flight (ToF) of an acoustic wave that propagates inside a piece of wood. In order to do this, two piezoelectric probes are used, nailed in the wood and separated a given distance longitudinally. The MOE can be derived from the propagation speed of the longitudinal acoustic wave if the density of the is known. For this reason, this device has the possibility of connecting a load cell for weighing logs or boards to estimate their density. It also has an expansion port reserved for future functionality. A methodology based on the Engineering Design Process (EDP) has been followed. The scope of this project embraces all aspects of the development of an electronic product from start to finish: conceptualization, specification of requirements, design, manufacture and verification. A project of this reach requires planning, advanced knowledge of signal analysis, electronics, design and manufacture of Printed Circuit Boards (PCB) and product design, as well as the development of a firmware for the embedded system, based on a RTOS. Prior to the design of the electronics, a Reverse Engineering process of some similar products of the competition is performed; as well as an exhaustive analysis of the signals coming from the piezoelectric sensors that are going to be used, and the frequency response characterization of the piezoelectric probes themselves. This project has as its ultimate goal the demonstration of the multidisciplinary knowledge of engineering, and the capacity of analysis, design and manufacturing by the author; his skill and professionalism in CAD and EDA software required for these tasks, as well as in the documentation of the entire process.El presente Trabajo de Fin de Grado tiene como objetivo el desarrollo de un dispositivo electrónico portátil capaz de cuantificar la rigidez de la madera de árboles en pie, trozas y tablas usando ensayos no destructivos (Non-Destructive Testing, NDT) por medio del análisis de ondas acústicas. Como indicador de la rigidez se usa el Módulo de Elasticidad (MOE), una figura estándar en la industria. Este TFG forma parte de LIFE Wood For Future, un proyecto de la Universidad de Granada (UGR) financiado por el programa LIFE de la Unión Europea. LIFEWood For Future tiene como objetivo recuperar el cultivo del chopo (populus sp.) en la Vega de Granada demostrando la viabilidad de su madera a través de bioproductos estructurales innovadores. Recuperar las choperas de Granada tendría grandes beneficios para la zona del Área Metropolitana: creación de puestos de trabajo locales y sostenibles, mejora de la biodiversidad, e incremento de la tasa de absorción de dióxido de carbono a largo plazo, contribuyendo a reducir la contaminación endémica del aire en Granada. Este Trabajo de Fin de Grado se ha desarrollado con la colaboración del grupo de investigación ADIME de la Escuela Técnica Superior de Ingeniería de Edificación (ETSIE) y el grupo de electrónica aeroespacial GranaSat de la UGR. El objetivo del dispositivo, denominado Tree Inspection Kit (TIK), es ser una herramienta innovadora, portátil y fácil de usar para el diagnóstico y clasificación no destructiva de la madera por medio de su MOE. TIK está dotado de la electrónica necesaria para medir el tiempo de tránsito (ToF) de una onda acústica que se propaga en el interior de una pieza de madera. Para ello, se utilizan dos sondas piezoeléctricas clavadas en la madera y separadas longitudinalmente una distancia conocida. De la velocidad de propagación de la onda longitudinal se puede derivar el MOE, previo conocimiento de la densidad del material. Por ello, este dispositivo cuenta con la posibilidad de conectarle una célula de carga y pesar trozas o tablas para estimar su densidad. También tiene un puerto de expansión reservado para funcionalidad futura. Se ha seguido una metodología basada en el Proceso de Diseño de Ingeniería (Engineering Design Process, EDP), abarcando todos los aspectos del desarrollo de un producto electrónico de principio a fin: conceptualización, especificación de requisitos, diseño, fabricación y verificación. Un proyecto de este alcance requiere de planificación, conocimientos avanzados de análisis de señales, de electrónica, de diseño y fabricación de Placas de Circuito Impreso (PCB) y de diseño de producto, así como el desarrollo de un firmware para el sistema empotrado, basado en un RTOS. Previo al diseño de la electrónica, se realiza un proceso de Ingeniería Inversa (Reverse Engineering) de algunos productos similares de la competencia; al igual que un exhaustivo análisis de las señales provenientes de los sensores piezoeléctricos que van a utilizarse y la caracterización en frecuencia de las propias sondas piezoeléctricas. Este proyecto tiene como fin último la demostración de los conocimientos multidisciplinares propios de la ingeniería y la capacidad de análisis, diseño y fabricación por parte del autor; su habilidad y profesionalidad en el software CAD y EDA requerido para estas tareas, así como en la documentación de todo el proceso.Unión Europe

Distributed Communication in Swarms of Autonomous Underwater Vehicles

Effective communication mechanisms are a key requirement for schools of submersible robots and their meaningful deployment. Large schools of identical submersibles require a fully distributed communication system which scales well and optimises for ”many-to-many” communication (omnicast, also known as gossiping). As an additional constraint, communication channels under water are typically very low bandwidth and short range. This thesis discusses possible electric and electro-magnetic wireless communication channels suitable for underwater environments. Theoretical findings on the omnicast communication problem are presented, as well as the implementation of a distributed time division multiple access (TDMA) scheduling algorithm in simulation and in hardware. It is shown theoretically and in simulation that short range links in a robotic swarm are actually an advantage, compared to links that cover large parts of the network. Experiments were carried out on custom-developed digital long-wave radio and optical link modules. The results of the experiments are used to revisit the initial assumptions on communication in multi-hop wireless networks