70 research outputs found

    Reconfigurable Antenna Systems: Platform implementation and low-power matters

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    Antennas are a necessary and often critical component of all wireless systems, of which they share the ever-increasing complexity and the challenges of present and emerging trends. 5G, massive low-orbit satellite architectures (e.g. OneWeb), industry 4.0, Internet of Things (IoT), satcom on-the-move, Advanced Driver Assistance Systems (ADAS) and Autonomous Vehicles, all call for highly flexible systems, and antenna reconfigurability is an enabling part of these advances. The terminal segment is particularly crucial in this sense, encompassing both very compact antennas or low-profile antennas, all with various adaptability/reconfigurability requirements. This thesis work has dealt with hardware implementation issues of Radio Frequency (RF) antenna reconfigurability, and in particular with low-power General Purpose Platforms (GPP); the work has encompassed Software Defined Radio (SDR) implementation, as well as embedded low-power platforms (in particular on STM32 Nucleo family of micro-controller). The hardware-software platform work has been complemented with design and fabrication of reconfigurable antennas in standard technology, and the resulting systems tested. The selected antenna technology was antenna array with continuously steerable beam, controlled by voltage-driven phase shifting circuits. Applications included notably Wireless Sensor Network (WSN) deployed in the Italian scientific mission in Antarctica, in a traffic-monitoring case study (EU H2020 project), and into an innovative Global Navigation Satellite Systems (GNSS) antenna concept (patent application submitted). The SDR implementation focused on a low-cost and low-power Software-defined radio open-source platform with IEEE 802.11 a/g/p wireless communication capability. In a second embodiment, the flexibility of the SDR paradigm has been traded off to avoid the power consumption associated to the relevant operating system. Application field of reconfigurable antenna is, however, not limited to a better management of the energy consumption. The analysis has also been extended to satellites positioning application. A novel beamforming method has presented demonstrating improvements in the quality of signals received from satellites. Regarding those who deal with positioning algorithms, this advancement help improving precision on the estimated position

    Wilis: Architectural Modeling of Wireless Systems

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    The performance of a wireless system depends on the wireless channel as well as the algorithms used in the transceiver pipelines. Because physical phenomena affect transceiver pipelines in difficult to predict ways, detailed simulation of the entire transceiver system is needed to evaluate even a single processing block. Further, some protocol validations require simulation of rare events (say, 1 bit error in 109 bits), which means the protocol must simulate for a long enough time for such events to materialize. This requirement coupled with the heavy computation typical of most physical-layer processing, rules out pure software solutions. In this paper we describe WiLIS, an FPGA-based hybrid hardware-software system designed to facilitate the development of wireless protocols. We then use WiLIS to evaluate several microarchitectures for measuring very low bit-error rates (BER). We demonstrate, for the first time, that the recently proposed SoftPHY can be implemented efficiently in hardware

    CorteXlab: A Cognitive Radio Testbed for Reproducible Experiments

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    International audienceThe efficiency and potential gain of cognitive radio and more generally opportunistic cooperative communications have been already demonstrated from a theoretical point of view and supported by various simulation results. Beyond these promising results, several questions remain open from a practical point of view. Addressing these issues is not straightforward because deploying complex heterogeneous systems for cooperative scenarios is tedious, time consuming and hardly reproducible. We propose to make a step in this direction by offering a new ex-perimental facility, called CorteXlab, that allows complex multi-node cognitive radio scenarios deployment from anywhere in the world. Our objective is neither to design new software defined radio (SDR) nodes nor to propose a new software framework, but rather to provide a comprehensive access to a large set of high performance SDR nodes. The CorteXlab facility offers a 167 m 2 electromagnetically (EM) shielded room and integrates a set of 24 universal software radio peripherals (USRPs) from National Instruments, 18 PicoSDR nodes from Nutaq and 42 IoT-Lab wireless sensor nodes from Hikob. CorteXlab is built upon the foundations of the SensLAB testbed and also exploits the free and open-source toolkit GNU Radio. Automation in scenario deployment, experiment start, stop and results collection is performed by an experiment controller, called Minus. CorteXlab is in its final stages of development and is already capable of running specific test scenarios. In this contribution, we show that CorteXlab is able to easily cope with the usual issues faced by other testbeds providing a reproducible experiment environment for CR experimentation

    Методи забезпечення гарантоздатності і функціональної безпеки безпроводової інфраструктури на основі апаратного розділення абонентів

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    В монографії проведено порівняння науково-методичних підходів щодо забезпечення безпеки в сфері безпроводових технологій (загроз, атак, моделей, шляхів захисту); розроблені технології підвищення рівня захищеності безпроводових мереж в умовах стороннього кібернети-чного впливу (методи модуляції сигналів і адаптивного підбору вільних каналів передавання даних, метод підвищення цілісності та доступності з використанням прискорюючих лінз, метод оцінки стану систем захисту безпроводових мереж); розглянуто технічні аспекти забезпечення функціональної безпеки та живучості безпроводових мереж і запропоновано шляхи практичної реалізації заходів із забезпечення безпеки безпроводових технологій

    IoT security and privacy assessment using software-defined radios

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    The Internet of Things (IoT) has seen exceptional adoption in recent years, resulting in an unprecedented level of connectivity in personal and industrial domains. In parallel, software-defined radio (SDR) technology has become increasingly powerful, making it a compelling tool for wireless security research across multiple communication protocols. Specifically, SDRs are capable of manipulating the physical layer of protocols in software, which would otherwise be implemented statically in hardware. This flexibility enables research that goes beyond the boundaries of protocol specifications. This dissertation pursues four research directions that are either enabled by software-defined radio technology, or advance its utility for security research. First, we investigate the anti-tracking mechanisms defined by the Bluetooth Low Energy (BLE) wireless protocol. This protocol, present in virtually all wearable smart devices, implements address randomization in order to prevent unwanted tracking of its users. By analyzing raw advertising data from BLE devices using SDRs, we identify a vulnerability that allows an attacker to track a BLE device beyond the address randomization defined by the protocol. Second, we implement a compact, SDR-based testbed for physical layer benchmarking of wireless devices. The testbed is capable of emulating multiple data transmissions and produce intentional signal corruption in very precisely defined ways in order to investigate receiver robustness and undefined device behavior in the presence of malformed packets. We subject a range of Wi-Fi and Zigbee devices to specifically crafted packet collisions and "truncated packets" as a way to fingerprinting wireless device chipsets. Third, we introduce a middleware framework, coined "Snout", to improves accessibility and usability of SDRs. The architecture provides standardized data pipelines as well as an abstraction layer to GNU Radio flowgraphs which power SDR signal processing. This abstraction layer improves usability and maintainability by providing a declarative experiment configuration format instead of requiring constant manipulation of the signal processing code during experimentation. We show that Snout does not result in significant computational overhead, and maintains a predictable and modest memory footprint. Finally, we address the visibility problem arising from the growing number of IoT protocols across large bands of radio spectrum. We model an SDR-based IoT monitor which is capable of scanning multiple channels (including across multiple protocols), and employs channel switching policies to maximize freshness of information obtained by transmitting devices. We present multiple policies and compare their performance against an optimal Markov Decision Process (MDP) model, as well as through event-based simulation using real-world device traffic. The results of this work demonstrate the use of SDR technology in privacy and security research of IoT device communication, and open up opportunities for further low-layer protocol discoveries that require the use of software-defined radio as a research tool

    Review of Recent Trends

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    This work was partially supported by the European Regional Development Fund (FEDER), through the Regional Operational Programme of Centre (CENTRO 2020) of the Portugal 2020 framework, through projects SOCA (CENTRO-01-0145-FEDER-000010) and ORCIP (CENTRO-01-0145-FEDER-022141). Fernando P. Guiomar acknowledges a fellowship from “la Caixa” Foundation (ID100010434), code LCF/BQ/PR20/11770015. Houda Harkat acknowledges the financial support of the Programmatic Financing of the CTS R&D Unit (UIDP/00066/2020).MIMO-OFDM is a key technology and a strong candidate for 5G telecommunication systems. In the literature, there is no convenient survey study that rounds up all the necessary points to be investigated concerning such systems. The current deeper review paper inspects and interprets the state of the art and addresses several research axes related to MIMO-OFDM systems. Two topics have received special attention: MIMO waveforms and MIMO-OFDM channel estimation. The existing MIMO hardware and software innovations, in addition to the MIMO-OFDM equalization techniques, are discussed concisely. In the literature, only a few authors have discussed the MIMO channel estimation and modeling problems for a variety of MIMO systems. However, to the best of our knowledge, there has been until now no review paper specifically discussing the recent works concerning channel estimation and the equalization process for MIMO-OFDM systems. Hence, the current work focuses on analyzing the recently used algorithms in the field, which could be a rich reference for researchers. Moreover, some research perspectives are identified.publishersversionpublishe
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