Design and Validation of a Software Defined Radio Testbed for DVB-T Transmission

This paper describes the design and validation of a Software Defined Radio (SDR) testbed, which can be used for Digital Television transmission using the Digital Video Broadcasting - Terrestrial (DVB-T) standard. In order to generate a DVB-T-compliant signal with low computational complexity, we design an SDR architecture that uses the C/C++ language and exploits multithreading and vectorized instructions. Then, we transmit the generated DVB-T signal in real time, using a common PC equipped with multicore central processing units (CPUs) and a commercially available SDR modem board. The proposed SDR architecture has been validated using fixed TV sets, and portable receivers. Our results show that the proposed SDR architecture for DVB-T transmission is a low-cost low-complexity solution that, in the worst case, only requires less than 22% of CPU load and less than 170 MB of memory usage, on a 3.0 GHz Core i7 processor. In addition, using the same SDR modem board, we design an off-line software receiver that also performs time synchronization and carrier frequency offset estimation and compensation

AI-driven ground robots: mobile edge computing and mmWave communications at work

The seamless integration of multiple radio access technologies (multi-RAT) and cloud/edge resources is pivotal for advancing future networks, which seek to unify distributed and heterogeneous computing and communication resources into a cohesive continuum system, tailored for mobile applications. Many research projects and focused studies are proposing solutions in this area, the impact of which is undoubtedly increased by moving from theoretical and simulation studies to experimental validations. To this aim, this paper proposes a testbed architecture that combines contemporary communication and cloud technologies to provide microservice-based mobile applications with the ability to offload part of their tasks to cloud/edge data centers connected by multi-RAT cellular networks. The testbed leverages Kubernetes, Istio service mesh, OpenFlow, public 5G networks, and IEEE 802.11ad mmWave (60 GHz) Wi-Fi access points. The architecture is validated through a use case in which a ground robot autonomously follows a moving object by using an artificial intelligence-driven computer vision application. Computationally intensive navigation tasks are offloaded by the robot to microservice instances, which are executed on demand within cloud and edge data centers that the robot can exploit during its journey. The proposed testbed is flexible and can be reused to assess communication and cloud innovations focusing on multi-RAT cloud continuum scenarios

Real-Time Generation of Standard-Compliant DVB-T Signals

This paper proposes and discusses two software implementations of the DVB-T modulator, using C++ and MATLAB, respectively. All the key features of the DVB-T standard are included. The C++ DVB-T modulator, incorporated into the Iris framework developed by Trinity College of Dublin, works in real time on an Intel Core i7 2.4 GHz CPU with the Iris testbed. The MATLAB-based DVB-T modulator is coupled with a receiver implementation with channel estimation, equalization, soft-output demapping and channel decoding. The validation step demonstrates that the proposed DVB-T software implementations generate standard-compliant DVB-T signals that are correctly received by commercially available TV sets and USB dongles. The software code for the Iris-based C++ modulator, and for the MATLAB-based modulator and receiver, has been made publicly available under the GNU license

Trocas gasosas influenciam na morfogênese in vitro de duas cultivares de oliveira (Olea europaea L.)

Os objetivos deste trabalho foram estabelecer in vitro as cultivares de oliveira 'Arbequina' e 'Maria da Fé' e avaliar a influência das tampas com membranas permeáveis a gases na morfogênese in vitro dessas cultivares. Inocularam-se segmentos nodais com gemas previamente descontaminadas pelo protocolo aqui desenvolvido. Utilizaram-se o delineamento inteiramente casualizado (DIC) em esquema fatorial 2³, duas cultivares; dois meios de cultura OM (Olive medium) (OM + 20 µM de zeatina [1]; e OM + 20 µM de zeatina + 10 µM de GA3 [2]); dois tipos de vedação (tampa rígida sem orifício e com membrana porosa) com cinco repetições/ tratamento; e a unidade experimental constituída por quatro tubos de ensaio. Avaliaram-se: a porcentagem de contaminação total; a porcentagem de contaminação fúngica e bacteriana; o número de gemas intumescidas; o número de brotos; e a porcentagem de oxidação. Aos 30 dias de cultivo, constatou-se a contaminação de 15% e 8,8% dos explantes de 'Arbequina' e 'Maria da Fé', respectivamente. Em 'Arbequina', 33,3% e 66,7% ocorreram por contaminação fúngica e bacteriana, respectivamente. Em 'Maria da Fé', 28,6% e 71,4% decorreram de contaminação fúngica e bacteriana, respectivamente. O número de gemas foi superior (p<0,05) em 'Arbequina', comparativamente à 'Maria da Fé', quando se utilizou tampa com membrana porosa para vedar os frascos. Em tampa rígida não houve diferença entre cultivares. O número de brotos no meio 1 foi superior estatisticamente (p<0,05) ao no meio 2. Não houve diferença estatística em porcentagem de oxidação. Sugere-se a utilização do protocolo de desinfestação aqui desenvolvido, como também do meio 1 e tampas com membranas porosas, pois isso favorecerá o desenvolvimento das gemas e a posterior formação de plantas

Factor graph based detection approach for high-mobility OFDM systems with large FFT modes

In this article, a novel detector design is proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency selective and time varying channels. Namely, we focus on systems with large OFDM symbol lengths where design and complexity constraints have to be taken into account and many of the existing ICI reduction techniques can not be applied. We propose a factor graph (FG) based approach for maximum a posteriori (MAP) symbol detection which exploits the frequency diversity introduced by the ICI in the OFDM symbol. The proposed algorithm provides high diversity orders allowing to outperform the free-ICI performance in high-mobility scenarios with an inherent parallel structure suitable for large OFDM block sizes. The performance of the mentioned near-optimal detection strategy is analyzed over a general bit-interleaved coded modulation (BICM) system applying low-density parity-check (LDPC) codes. The inclusion of pilot symbols is also considered in order to analyze how they assist the detection process