Implementação do protocolo IEEE 802.11ah através de rádio definido por software

O crescente uso de redes conhecidas como Internet das Coisas (IoT) constitui oportunidade para um vasto campo de pesquisa e desenvolvimento, onde diversos protocolos oferecem soluções práticas distintas. Entre estes, o protocolo IEEE 802.11ah é uma alternativa de livre implementação que utiliza uma faixa de espectro não licenciada abaixo de 1 GHz. Este trabalho oferece contribuições para a implementação de técnicas de comunicação adequadas a redes de sensores sem fio (WSN) baseadas no padrão IEEE 802.11ah (Wi-Fi HaLow). De forma a facilitar trabalhos futuros de pesquisa e devido a baixa disponibilidade de dispositivos comerciais, uma plataforma de rádio definido por software foi utilizada para realizar a implementação de um enlace em camada física a partir da especificação do protocolo e de uma implementação pré-existente que comtempla as características de modulação fundamentais do protocolo. Foram conduzidos testes e experimentos de bancada para avaliar o desempenho dos dispositivos, em situações de interferência e ruído. As condições de interferência foram um sinal senoidal, um sinal LoRa e um sinal O-QPSK derivado do protocolo IEEE 802.15.4, uma vez que ocupam a mesma banda de frequências do protocolo avaliado. Também foi avaliada a rejeição a sinais interferente IEEE 802.11ah sobrepostos no mesmo canal, em canal adjacente e em canal não adjacente. As simulações e experimentos geraram um conjunto de dados que foram analisados conforme os requisitos da especificação e da literatura, atendendo o desempenho especificado. Os valores limites para estas interferências são demonstrados em termos de diferenças de potências. O código-fonte será disponibilizado publicamente, para servir de base a trabalhos futuros que tenham por objetivo avaliar o desempenho do protocolo IEEE 802.11ah sob outros aspectos ou provar ideias teóricas inovadoras que, embora propostas e demonstradas de forma simulada, por vezes não encontram comprovação em hardware.The Internet of Things (IoT) environment is an expanding field with many competing standards solving various communication challenges. However, interesting theoretical propositions, demonstrated in simulations during research, end up not getting a quick implementation in hardware. This work provides contributions towards an implementation of the IEEE 802.11ah (Wi-Fi HaLow) standard, an extension of the Wi-Fi protocol focused on providing IoT-like connectivity on midrange sites (up to 1 km). A softwaredefined radio plataform, programmed with open-source software, is used to provide an extensible code base, derived from existing works. Simulation and experimental measurements were conducted towards evaluating the performance and limitations in interference and noise environments. As interference, sinusoidal, LoRa and IEEE 802.15.4 O-QPSK derived signals were used as to evaluate the minimum difference of powers necessary to garantee the IEEE 802.11ah signal is received and correctly decoded with 90 % packet delivery rate. Adjacent, non adjacent and same channel rejection were also evaluated. All results agree with the requirements presented in the standard. We make the source code freely available in the Internet as to enable future modifications and derived works

Multi-Protocol Sensor Node for Internet of Things (IoT) Applications

This paper will describe the implementation of an end-to-end IoT solution, focusing specifically in the multi-protocol sensor node using Pycom's FiPy board. A performance assessment will be presented, addressing a comparison between the different protocols (LoRa vs. Wi-Fi) in terms radio coverage, timing issues, power consumption/battery usage, among others. Further, it will be investigated the integration onto the sensor node different sensor/actuator circuit blocks for energy metering on industrial machinery as a way to optimize energy efficiency metrics. This will provide a practical use case in the field of Industry 4.0, leading to insights for power quality monitoring

Internet of Things From Hype to Reality

The Internet of Things (IoT) has gained significant mindshare, let alone attention, in academia and the industry especially over the past few years. The reasons behind this interest are the potential capabilities that IoT promises to offer. On the personal level, it paints a picture of a future world where all the things in our ambient environment are connected to the Internet and seamlessly communicate with each other to operate intelligently. The ultimate goal is to enable objects around us to efficiently sense our surroundings, inexpensively communicate, and ultimately create a better environment for us: one where everyday objects act based on what we need and like without explicit instructions

Towards the efficient use of LoRa for wireless sensor networks

Since their inception in 1998 with the Smart Dust Project from University of Berkeley, Wireless Sensor Networks (WSNs) had a tremendous impact on both science and society, influencing many (new) research fields, like Cyber-physical System (CPS), Machine to Machine (M2M), and Internet of Things (IoT). In over two decades, WSN researchers have delivered a wide-range of hardware, communication protocols, operating systems, and applications, to deal with the now classic problems of resourceconstrained devices, limited energy sources, and harsh communication environments. However, WSN research happened mostly on the same kind of hardware. With wireless communication and embedded hardware evolving, there are new opportunities to resolve the long standing issues of scaling, deploying, and maintaining a WSN. To this end, we explore in this work the most recent advances in low-power, longrange wireless communication, and the new challenges these new wireless communication techniques introduce. Specifically, we focus on the most promising such technology: LoRa. LoRa is a novel low-power, long-range communication technology, which promises a single-hop network with millions of sensor nodes. Using practical experiments, we evaluate the unique properties of LoRa, like orthogonal spreading factors, nondestructive concurrent transmissions, and carrier activity detection. Utilising these unique properties, we build a novel TDMA-style multi-hop Medium Access Control (MAC) protocol called LoRaBlink. Based on empirical results, we develop a communication model and simulator called LoRaSim to explore the scalability of a LoRa network. We conclude that, in its current deployment, LoRa cannot support the scale it is envisioned to operate at. One way to improve this scalability issue is Adaptive Data Rate (ADR). We develop two ADR protocols, Probing and Optimistic Probing, and compare them with the de facto standard ADR protocol used in the crowdsourced TTN LoRaWAN network. We demonstrate that our algorithms are much more responsive, energy efficient, and able to reach a more efficient configuration quicker, though reaching a suboptimal configuration for poor links, which is offset by the savings caused by the convergence speed. Overall, this work provides theoretical and empirical proofs that LoRa can tackle some of the long standing problems within WSN. We envision that future work, in particular on ADR and MAC protocols for LoRa and other low-power, long-range communication technologies, will help push these new communication technologies to main-stream status in WSNs

Non-Orthogonal Signal and System Design for Wireless Communications

The thesis presents research in non-orthogonal multi-carrier signals, in which: (i) a new signal format termed truncated orthogonal frequency division multiplexing (TOFDM) is proposed to improve data rates in wireless communication systems, such as those used in mobile/cellular systems and wireless local area networks (LANs), and (ii) a new design and experimental implementation of a real-time spectrally efficient frequency division multiplexing (SEFDM) system are reported. This research proposes a modified version of the orthogonal frequency division multiplexing (OFDM) format, obtained by truncating OFDM symbols in the time-domain. In TOFDM, subcarriers are no longer orthogonally packed in the frequency-domain as time samples are only partially transmitted, leading to improved spectral efficiency. In this work, (i) analytical expressions are derived for the newly proposed TOFDM signal, followed by (ii) interference analysis, (iii) systems design for uncoded and coded schemes, (iv) experimental implementation and (v) performance evaluation of the new proposed signal and system, with comparisons to conventional OFDM systems. Results indicate that signals can be recovered with truncated symbol transmission. Based on the TOFDM principle, a new receiving technique, termed partial symbol recovery (PSR), is designed and implemented in software de ned radio (SDR), that allows efficient operation of two users for overlapping data, in wireless communication systems operating with collisions. The PSR technique is based on recovery of collision-free partial OFDM symbols, followed by the reconstruction of complete symbols to recover progressively the frames of two users suffering collisions. The system is evaluated in a testbed of 12-nodes using SDR platforms. The thesis also proposes channel estimation and equalization technique for non-orthogonal signals in 5G scenarios, using an orthogonal demodulator and zero padding. Finally, the implementation of complete SEFDM systems in real-time is investigated and described in detail

ROBUST AND RELIABLE WIRELESS COMMUNICATION BETWEEN SMART NOx SENSOR AND THE SPEEDGOAT/ENGINE CONTROL MODULE: A case study of Wärtsilä’s smart NOx sensor and W4L20 Diesel Engine

In recent years, the industrial applications of the wireless transmission of data acquired through sensors have been growing. Addressing the challenges or requirements that come with this needs the integration of new product designs and manufacturing techniques with automation devices. Factors like development time, security, reliability, transmission in an industrial environment, data rate, battery life with energy harvesting capabilities, etc. are of major concerns. This thesis is based on the Wärtsilä smart NOx sensor case study which investigates the possibility of replacing the existing wired CAN bus connection between the smart NOx sensor and the rapid control prototyping system speedgoat and possibly in the future the Engine Control Unit (ECU) with a wireless communication solution. The designed prototype would wirelessly transmit the smart NOx sensor data. The smart NOx sensor data is received using a CAN bus integrated with a wireless transmitter module. The wireless receiver module receives the data and then relays the CAN frames through an integrated CAN Bus to the speedgoat. A matlab simulink module has been programmed into the speedgoat to receive the CAN frames, calculate O2% and NOx ppm values and display the results on a monitor connected to the speedgoat. Criteria like transmission in industrial environments, packet loss, RSSI, bit error rate, reliability and security of the wireless solution are analyzed. According to the analysis done and best practices, a wireless solution is recommended and implemented. The wireless-CAN prototype is installed on the Wärtsilä W4L20 diesel engine in VEBIC for monitoring and observation.fi=Opinnäytetyö kokotekstinä PDF-muodossa.|en=Thesis fulltext in PDF format.|sv=Lärdomsprov tillgängligt som fulltext i PDF-format

Monitoraggio ambientale tramite tecnologia LoRaWAN: misurazioni sperimentali e piattaforma di data analytics

I requisiti di molte applicazioni IoT necessitano di trasmettere dati su lunghe distanze, con basso data rate e con il minor impatto possibile sul consumo energetico. Le tecnologie LPWAN (Low Power Wide Area Network) sono state progettate per complementare ed in alcuni casi sostituire le soluzioni offerte dalla reti cellulari e dalle reti di sensori a corto/medio raggio. Nonostante la pletora di standards LPWAN disponibili sul mercato, la tecnologia LoRa/LoRaWAN sta riscuotendo notevole successo grazie alle performance che riesce a garantire. L’imponente mole di dati generata dalle applicazioni IoT richiede soluzioni in grado di poter archiviare e gestire in maniera efficiente il ciclo di vita delle informazioni. L’utilizzo di piattaforme di data analytics basate su sistemi NoSQL permettono una gestione più agile dei Big Data. In questa tesi è stata progettata ed implementata un’infrastruttura per il monitoraggio ambientale tramite LoRaWAN e la relativa piattaforma di data analytics adoperata per lo studio delle metriche relative alla trasmissione radio LoRa. I risultati ottenuti dalla sperimentazione possono essere usati per fare tuning delle configurazioni per il deploy in contesti reali