G-Shaped Antenna Mounted On USB Dongle Optimized For MIMO Applications Under WLAN 5.2/5.8/5.9

In this study, we used a G-shaped antenna due to its ease of integration into the overall design. The basic structure was adapted from a model proposed by W.-C. Liu. Then, we integrated it into a USB dongle, then added another antenna element to use it for MIMO applications in WLAN networks. A neutralization line is added between these two antenna elements to increase insulation

Review of Recent Trends

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

Bio-Inspired Mechanism for Aircraft Assessment Under Upset Conditions

Based on the artificial immune systems paradigm and a hierarchical multi-self strategy, a set of algorithms for aircraft sub-systems failure detection, identification, evaluation and flight envelope estimation has been developed and implemented. Data from a six degrees-of-freedom flight simulator were used to define a large set of 2-dimensional self/non-self projections as well as for the generation of antibodies and identifiers designated for health assessment of an aircraft under upset conditions. The methodology presented in this paper classifies and quantifies the type and severity of a broad number of aircraft actuators, sensors, engine and structural component failures. In addition, the impact of these upset conditions on the flight envelope is estimated using nominal test data. Based on immune negative and positive selection mechanisms, a heuristic selection of sub-selves and the formulation of a mapping- based algorithm capable of selectively capturing the dynamic fingerprint of upset conditions is implemented. The performance of the approach is assessed in terms of detection and identification rates, false alarms, and correct prediction of flight envelope reduction with respect to specific states. Furthermore, this methodology is implemented in flight test by using an unmanned aerial vehicle subjected to nominal and four different abnormal flight conditions instrumented with a low cost microcontroller

Comparison of vertical handover decision-based techniques in heterogeneous networks

Industry leaders are currently setting out standards for 5G Networks projected for 2020 or even sooner. Future generation networks will be heterogeneous in nature because no single network type is capable of optimally meeting all the rapid changes in customer demands. Heterogeneous networks are typically characterized by some network architecture, base stations of varying transmission power, transmission solutions and the deployment of a mix of technologies (multiple radio access technologies). In heterogeneous networks, the processes involved when a mobile node successfully switches from one radio access technology to the other for the purpose of quality of service continuity is termed vertical handover or vertical handoff. Active calls that get dropped, or cases where there is discontinuity of service experienced by mobile users can be attributed to the phenomenon of delayed handover or an outright case of an unsuccessful handover procedure. This dissertation analyses the performance of a fuzzy-based VHO algorithm scheme in a Wi-Fi, WiMAX, UMTS and LTE integrated network using the OMNeT++ discrete event simulator. The loose coupling type network architecture is adopted and results of the simulation are analysed and compared for the two major categories of handover basis; multiple and single criteria based handover methods. The key performance indices from the simulations showed better overall throughput, better call dropped rate and shorter handover time duration for the multiple criteria based decision method compared to the single criteria based technique. This work also touches on current trends, challenges in area of seamless handover and initiatives for future Networks (Next Generation Heterogeneous Networks)

A state-of-the-art assessment of active structures

A state-of-the-art assessment of active structures with emphasis towards the applications in aeronautics and space is presented. It is felt that since this technology area is growing at such a rapid pace in many different disciplines, it is not feasible to cover all of the current research but only the relevant work as relates to aeronautics and space. Research in smart actuation materials, smart sensors, and control of smart/intelligent structures is covered. In smart actuation materials, piezoelectric, magnetostrictive, shape memory, electrorheological, and electrostrictive materials are covered. For sensory materials, fiber optics, dielectric loss, and piezoelectric sensors are examined. Applications of embedded sensors and smart sensors are discussed

Analysis and Design of Non-Orthogonal Multiple Access (NOMA) Techniques for Next Generation Wireless Communication Systems

The current surge in wireless connectivity, anticipated to amplify significantly in future wireless technologies, brings a new wave of users. Given the impracticality of an endlessly expanding bandwidth, there’s a pressing need for communication techniques that efficiently serve this burgeoning user base with limited resources. Multiple Access (MA) techniques, notably Orthogonal Multiple Access (OMA), have long addressed bandwidth constraints. However, with escalating user numbers, OMA’s orthogonality becomes limiting for emerging wireless technologies. Non-Orthogonal Multiple Access (NOMA), employing superposition coding, serves more users within the same bandwidth as OMA by allocating different power levels to users whose signals can then be detected using the gap between them, thus offering superior spectral efficiency and massive connectivity. This thesis examines the integration of NOMA techniques with cooperative relaying, EXtrinsic Information Transfer (EXIT) chart analysis, and deep learning for enhancing 6G and beyond communication systems. The adopted methodology aims to optimize the systems’ performance, spanning from bit-error rate (BER) versus signal to noise ratio (SNR) to overall system efficiency and data rates. The primary focus of this thesis is the investigation of the integration of NOMA with cooperative relaying, EXIT chart analysis, and deep learning techniques. In the cooperative relaying context, NOMA notably improved diversity gains, thereby proving the superiority of combining NOMA with cooperative relaying over just NOMA. With EXIT chart analysis, NOMA achieved low BER at mid-range SNR as well as achieved optimal user fairness in the power allocation stage. Additionally, employing a trained neural network enhanced signal detection for NOMA in the deep learning scenario, thereby producing a simpler signal detection for NOMA which addresses NOMAs’ complex receiver problem

Propagação de sinais de rádio sobre fibra no contexto de NG-PON2

Mestrado em Engenharia Electrónica e TelecomunicaçõesHoje em dia todas os pessoas estão ligadas em rede, e devido a proliferação de diversos serviços torna-se cada vez mais imprescindvél arranjar novas opções para fornecer a maior largura de banda possvél, para responder as necessidade geradas. As redes oticas passivas de próxima geração surgem como a solução fornecendo ritmos de transmissão na ordem dos Terabits/s e um alcance na ordem dos milhares de kilometros. Neste contexto será falado dos sinais de rádio na fibra, que trazem vantagens ao nível da simpli ficação das estações base, possibilitando poupança nos custos, isto ao integrar a tecnologia de rádio com a tecnologia de fibra existente Neste trabalho iniciou-se pelo estudo da literatura existente das arquitectura existentes de radio-sobre- fibra, bem como as suas limitações. De seguida, procedeu-se ao desenvolvimento de uma plataforma de simulação para estudar os fenomenos que o sinal de rádio sofre ao ser transportado no sistema otico. Por ultimo, foram realizadas experiências laboratoriais, primeiro com um transceiver NG-PON2 e depois com um sistema rádio-sobre-fibra, consistindo o objectivo em caracterizar estes sistemas.Nowadays all the people are connected on a network, and due to the proliferation of several services it becomes indispensable to nd new option to provide as more bandwidth as possible to answer to necessity. The next generation passive optical networks rise as a solution to supply transmission rate on the Terabits/s order and a reach on the order of the thousands kilometers. On this context, the radio-over- ber signals are going to be spoken about, which o er advantages by the simpli cation of base stations, allowing lower costs, and this by composing the radio technology with the already existent ber technology. This work initiated by the study of the existent literature of the radio-over- ber architectures, as well as their limitations. Then, proceeded on the development of a simulation platform to study the phenomenons that a radio-over- ber su ers while going through the optical system. For last, laboratory experiments were carried out rst with a NG-PON2 transceiver and then with a radio-over- ber system, being the objective of characterizing these systems

Practical free-space quantum key distribution

Within the last two decades, the world has seen an exponential increase in the quantity of data traffic exchanged electronically. Currently, the widespread use of classical encryption technology provides tolerable levels of security for data in day to day life. However, with one somewhat impractical exception these technologies are based on mathematical complexity and have never been proven to be secure. Significant advances in mathematics or new computer architectures could render these technologies obsolete in a very short timescale. By contrast, Quantum Key Distribution (or Quantum Cryptography as it is sometimes called) offers a theoretically secure method of cryptographic key generation and exchange which is guaranteed by physical laws. Moreover, the technique is capable of eavesdropper detection during the key exchange process. Much research and development work has been undertaken but most of this work has concentrated on the use of optical fibres as the transmission medium for the quantum channel. This thesis discusses the requirements, theoretical basis and practical development of a compact, free-space transmission quantum key distribution system from inception to system tests. Experiments conducted over several distances are outlined which verify the feasibility of quantum key distribution operating continuously over ranges from metres to intercity distances and finally to global reach via the use of satellites

Developing a Transient Photovoltaic Inverter Model in OpenDSS Using the Hammerstein-Wiener Mathematical Structure

Photovoltaic (PV) modules (direct current) have continued to decrease in price over the past decade causing the number of PV installations to increase. With increase in use of PV renewable resources come more interconnections to the electrical power grid and hence system protection challenges for planning engineers. PV inverters (direct current to alternating current interconnections) do not behave like traditional generators having rotational inertia and long-lived electrical time constants. In contrast, inverters have no inertial mass and very short time constants. Manufacturers do not provide inverter design details. Therefore, current inverter circuit models available for studying inverter behavior and completing inverter grid integration tasks are not adequate. In addition, the inverter models currently used by planning engineers only provide steady state solutions; not accurate time-domain results for rapid load changes especially during electrical circuit fault conditions. Inadequate and inaccurate planning models result in unreliable system protection designs, leading to possible operational failure, mis-coordination of protective equipment, and system damage. Valid transient models are necessary to plan for unusual circuit conditions including overvoltages, grounding conditions, and anti-islanding on electric grid feeders connected to photovoltaic resources or utilities desiring to add photovoltaic resources to an existing feeder. This research makes an original contribution by providing a modeling solution for solar PV inverter transients using the Hammerstein-Wiener (HW) mathematical structure. The analysis is based on laboratory test data from single-phase, micro, and three-phase inverters. Data was collected during open-circuit, short-circuit and voltage sag events. Each inverter was tested at multiple output power levels and multiple tests were run for each case to account for point-on-wave effects on the transient magnitudes. The HW framework, which integrates linear dynamics and nonlinearities, provides a framework for the transient PV inverter model. The model was incorporated into an open source distribution simulation software; OpenDSS. Test results show that PV inverters cause significant over-voltages and over-currents during transient events, but these have been difficult to predict accurately in simulations. The OpenDSS model provides a solution for modeling these nonlinear behaviors for design and operating studies and can be expanded to incorporate other power system components