Sincronização de quadro e frequência para OFDM no padrão IEEE 802.15.4g : algoritmos e implementação em hardware

Orientadores: Renato da Rocha Lopes, Eduardo Rodrigues de LimaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: O objetivo deste trabalho é propor métodos de sincronização de quadro e de frequência de portadora para a camada física MR-OFDM do padrão IEEE 802.15.4g, começando pela pesquisa de algoritmos, passando pelas etapas de modelagem e simulação em alto nível, e finalmente implementando e avaliando os métodos propostos em hardware. A sincronização de quadro é o processo responsável por detectar o início do dado transmitido, ou seja, a primeira amostra válida do sinal de interesse. No caso de sistemas OFDM, onde o sinal transmitido é composto por um ou mais símbolos OFDM (cada símbolo sendo composto por uma quantidade fixa de amostras), o objetivo é detectar a borda ou janelamento de tais símbolos OFDM, ou seja, onde começa e termina cada um deles. A sincronização de frequência, por sua vez, consiste em estimar e compensar o erro de frequência de portadora, causado principalmente pelo descasamento dos osciladores do transmissor e do receptor. Com base em estudos preliminares, selecionamos o algoritmo de Minn para a detecção de quadro. Para a correção de erro de frequência, dividimos o processo em duas etapas, como é geralmente proposto na literatura: primeiro, o erro de frequência fracionário é estimado no domínio do tempo durante a detecção de quadro e compensado via rotação de sinal; após a conversão do domínio do tempo para o domínio da frequência, o erro de frequência inteiro é estimado e compensado utilizando um novo e simples algoritmo que será proposto e detalhado neste trabalho. Os algoritmos propostos foram implementados em hardware e uma plataforma de verificação baseada em FPGA foi criada para avaliar o seu desempenho. Os módulos implementados são parte de um projeto que está sendo desenvolvido no Instituto de Pesquisa Eldorado (Campinas) que tem como objetivo implementar em ASIC um transceptor compatível com o padrão IEEE 802.15.4gAbstract: The objective of this work is proposing methods of frame and frequency synchronization for the MR-OFDM PHY of IEEE 802.15.4g standard, starting with the research of state-of-the-art algorithms, passing through modeling, high-level simulations, and finally implementing and evaluating the proposed methods in hardware. Frame synchronization is the process responsible for detecting the beginning of transmitted data and, in the case of OFDM systems, the border of each OFDM symbol, while frequency synchronization consists of estimating and compensating the Carrier Frequency Offset (CFO) caused mainly by a mismatch between the transmitter and receiver oscillators. Based on the initial studies, we selected Minn¿s algorithm for frame detection. For the CFO correction, we split the process into two steps, as commonly proposed in the literature: first, the Fractional CFO is estimated in the time domain during the frame detection and compensated via signal rotation; after the conversion from time to frequency domain, the Integer CFO is estimated and compensated with a novel and simple algorithm that will be detailed in this work. The proposed algorithms were implemented in hardware and inserted in an FPGA-based verification platform for performance measurement. The implemented modules are part of a project that is under development at Eldorado Research Institute (Campinas) and aims to implement in ASIC a transceiver compliant to the IEEE 802.15.4g standardMestradoTelecomunicações e TelemáticaMestra em Engenharia Elétric

Intra-network interference robustness : an empirical evaluation of IEEE 802.15.4-2015 SUN-OFDM

While IEEE 802.15.4 and its Time Slotted Channel Hopping (TSCH) medium access mode were developed as a wireless substitute for reliable process monitoring in industrial environments, most deployments use a single/static physical layer (PHY) configuration. Instead of limiting all links to the throughput and reliability of a single Modulation and Coding Scheme (MCS), you can dynamically re-configure the PHY of link endpoints according to the context. However, such modulation diversity causes links to coincide in time/frequency space, resulting in poor reliability if left unchecked. Nonetheless, to some level, intentional spatial overlap improves resource efficiency while partially preserving the benefits of modulation diversity. Hence, we measured the mutual interference robustness of certain Smart Utility Network (SUN) Orthogonal Frequency Division Multiplexing (OFDM) configurations, as a first step towards combining spatial re-use and modulation diversity. This paper discusses the packet reception performance of those PHY configurations in terms of Signal to Interference Ratio (SIR) and time-overlap percentage between interference and targeted parts of useful transmissions. In summary, we found SUN-OFDM O3 MCS1 and O4 MCS2 performed best. Consequently, one should consider them when developing TSCH scheduling mechanisms in the search for resource efficient ubiquitous connectivity through modulation diversity and spatial re-use

Uso de técnicas de combinação de diversidade e fatores de espalhamento estendidos para melhorar a performance e reduzir a complexidade do receptor OFDM em IEEE 802.15.4g

Orientadores: Renato da Rocha Lopes, Eduardo Rodrigues de LimaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: EEE 802.15.4g é um adendo da norma IEEE 802.15.4 focada em Smart Utility Network (SUN), e dedicada a requisitos de comunicação no contexto de Low Rate (LR) Wireless Personal Area Network (WPAN). Hoje em dia, devido às suas características, o adendo foca em apliações de Smart Ubiquitous Network, como cidades inteligentes e Internet das Coisas (IoT). Uma das três Camadas Físicas (PHYs) definidas na norma é a Multi-Rate and Multi-Regional Orthogonal Frequency Division Multiplexing (MR-OFDM). Além de outras características, o MR-OFDM emprega o método Frequency Spreading (FS) para reduzir a Peak-to-Average Power Ratio (PAPR) do símbolo OFDM. Sob algumas premissas do canal, este trabalho mostra que o FS também pode introduzir diversidade em frequência à camada física. Este trabalho propõe um método para reverter o espalhamento de frequência que explora diversidade em IEEE 802.15.4g MR-OFDM. O método segue duas abordagens: o uso de técnicas de combinação de diversidade e a proposta de novas configurações de Modulation and Coding Scheme (MCS) usando fatores de espalhamento estendidos. Em um canal com distribuição Rayleigh e assumindo subportadoras não correlacionadas, o método proposto mostra melhorias de até 10.35 dB quando comparado ao MR-OFDM, revertendo o espa-lhamento de frequência de forma direta, usando configurações originais. O método é válido mesmo na presença de erros na estimativa do canal e bandas de coerência largas. O trabalho faz parte de um projeto maior que visa a implementação de um circuito integrado capaz de suportar as três camadas físicas definias em IEEE 802.15.4g, não apenas o MR-OFDM. Devido a isso, o método deve ser totalmente compatível com a norma e focar na complexidade de implementação do receptor MR-OFDMAbstract: IEEE 802.15.4g is an amendment of the IEEE 802.15.4 standard focused on Smart Utility Networks (SUN), and devoted to the communication requirements of Low Rate Wireless Personal Area Network (LR-WPAN). Nowadays, due to its characteristics, the amendment focuses on Smart Ubiquitous Network applications, such as Smart City and Internet of Things (IoT). One of the three Physical Layers (PHYs) defined in the standard is the Multi-Rate and Multi-Regional Orthogonal Frequency Division Multiplexing (MR-OFDM). In addition to other features, the MR-OFDM employs frequency spreading to reduce the Peak-to-Average Power Ratio (PAPR) of the OFDM symbol. Under some channel assumptions, this frequency spreading can also introduce frequency diversity to the PHY. This work proposes a method to perform frequency despreading that exploits diversity in the IEEE 802.15.4g MR-OFDM PHY. The method follows two approaches: the use of diversity combining techniques and the proposal of new Modulation and Coding Scheme (MCS) configurations using extended spreading factors. In a channel with Rayleigh distribution and assuming uncorrelated subcarriers, the proposed method shows improvements up to 10.35 dB when compared to the MR-OFDM performing frequency despreading using original configurations. The method is valid even in the presence of channel estimation errors and large channel coherence bandwidths. The work is part of a larger project which aims at the implementation of an Integrated Circuit capable of handling the three PHYs defined in the IEEE802.15.4g, not only the MR-OFDM. Thus, the method must be fully compliant to the standard and focus on the MR-OFDM receiver implementation complexityMestradoTelecomunicações e TelemáticaMestre em Engenharia Elétric

Étude de la fiabilité des communications dans un réseau de capteurs sans-fils appliqué aux mines souterraines

Étude de la fiabilité des communications dans un réseau de capteurs sans-fils appliqué aux mines souterraines Certes, l’aspect sécurité est le plus préoccupant du travail dans les mines souterraines. Aujourd’hui, plusieurs équipements hautement technologiques sont utilisés dans la mine. Parmi ces équipements, nous pouvons distinguer les outils de communications. En effet, dans une mine bien équipée, plusieurs sortes de réseaux informatiques sont déployés à des fins de sécurité et de supervision. Dans ce contexte, les réseaux de capteurs sans-fils (RCSF) sont de plus en plus utilisés dans la mine. Cela s’explique par le fait que ce type de réseau orienté application apporte plusieurs avantages par rapport aux réseaux classiques à savoir le caractère sans-fils, le faible coût, la tolérance à la défaillance et la facilité de déploiement dans les zones à haut risque. Cependant, les RCSF imposent quelques limitations qui ne sont pas considérées dans les réseaux classiques dont notamment la consommation d’énergie et la gestion des informations. L'enjeu de l’utilisation des RCSF dans la mine est de mettre en place des communications efficaces énergétiquement qui tiennent compte des différentes contraintes imposées par les équipements hétérogènes. Dans cette optique, le standard IEEE 802.15.4 apparaît comme un standard de fait pour les RCSF. Le succès de cette norme est visible dans le fait qu’aujourd'hui, il y a plus de dix couches physiques différentes proposées comme extension à la norme IEEE 802.15.4. C’est dans ce contexte que se positionne l’objectif de notre travail. Il s’agit dans notre projet de faire l’étude des performances du standard IEEE 802.15.4 en comparaison avec l’extension IEEE 802.15.4g. L’étude comparative des standards IEEE 802.15.4/4g par simulation et par un banc d’essai a fait l’objet de nos travaux. Les résultats de simulation ont été démontrés pour différent scénarios d’utilisation

Multi-band sub-GHz technology recognition on NVIDIA’s Jetson Nano

Low power wide area networks support the success of long range Internet of things applications such as agriculture, security, smart cities and homes. This enormous popularity, however, breeds new challenging problems as the wireless spectrum gets saturated which increases the probability of collisions and performance degradation. To this end, smart spectrum decisions are needed and will be supported by wireless technology recognition to allow the networks to dynamically adapt to the ever changing environment where fair co-existence with other wireless technologies becomes essential. In contrast to existing research that assesses technology recognition using machine learning on powerful graphics processing units, this work aims to propose a deep learning solution using convolutional neural networks, cheap software defined radios and efficient embedded platforms such as NVIDIA’s Jetson Nano. More specifically, this paper presents low complexity near-real time multi-band sub-GHz technology recognition and supports a wide variety of technologies using multiple settings. Results show accuracies around 99%, which are comparable with state of the art solutions, while the classification time on a NVIDIA Jetson Nano remains small and offers real-time execution. These results will enable smart spectrum management without the need of expensive and high power consuming hardware

Design of an efficient binary phase-shift keying based IEEE 802.15.4 transceiver architecture and its performance analysis

The IEEE 802.15.4 physical layer (PHY) standard is one of the communication standards with wireless features by providing low-power and low-data rates in wireless personal area network (WPAN) applications. In this paper, an efficient IEEE 802.15.4 digital transceiver hardware architecture is designed using the binary phase-shift keying (BPSK) technique. The transceiver mainly has transmitter and receiver modules along with the error calculation unit. The BPSK modulation and demodulation are designed using a digital frequency synthesizer (DFS). The DFS is used to generate the in-phase (I) and quadrature-phase (Q) signals and also provides better system performance than the conventional voltage-controlled oscillator (VCO) and look up table (LUT) based memory methods. The differential encoding-decoding mechanism is incorporated to recover the bits effectively and to reduce the hardware complexity. The simulation results are illustrated and used to find the error bits. The design utilizes less chip area, works at 268.2 MHz, and consumes 108 mW of total power. The IEEE 802.15.4 transceiver provides a latency of 3.5 clock cycles and works with a throughput of 76.62 Mbps. The bit error rate (BER) of 2×10-5 is achieved by the proposed digital transceiver and is suitable for real-time applications. The work is compared with existing similar approaches with better improvement in performance parameters

Comparação experimental do desempenho de tecnologias emergentes de low power wide area networks para IoT

Orientadores: Gustavo Fraidenraich, Eduardo Rodrigues de LimaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de ComputaçãoResumo: Esta dissertação apresenta resultados experimentais para a avaliação de dois circuitos integrados para conectividade IoT, usando uma abordagem sistemática. Um dos circuitos é dedicado a LoRa, enquanto o outro utiliza o padrão IEEE 802.15.4g adotado pela Wi-SUN Alliance. O objetivo desta avaliação é apresentar resultados que possam ajudar todos que pretendem utilizar LoRa, IEEE 802.15.4g/Wi-SUN ou outras opções de conectividade, facilitando a comparação entre essas tecnologias de forma justa e coerente. Os resultados mostram que existem diferenças entre os valores apresentados nos datasheet e os valores medidos durante os experimentos. Existem várias razões que justificam essas divergências, como a configuração dos experimentos, calibração dos equipamentos, o tamanho dos pacotes transmitidos e até as especificações dos testes. Esse resultado reforça a importância de uma abordagem sistemática para a comparação entre tecnologiasAbstract: This dissertation presents experimental results on the evaluation of two commercial integrated circuits for IoT connectivity, using a systematic approach. One of the integrated circuits is devoted to LoRa and the other to IEEE 802.15.4g, which is the physical layer adopted by the WI-SUN Alliance. The goal behind this evaluation is to present results to support those who will make use of LoRa, IEEE802.15.4g/Wi-SUN, or other types of connectivity to fairly compare the technologies. The results show that there are differences between datasheet values and the measures collected during the experiments. There are several reasons for this divergence, such as the experimental setup, equipment calibration, transmitted packet length, and test specifications. This highlights the importance of a systematical approach when comparing technologiesMestradoTelecomunicações e TelemáticaMestre em Engenharia Elétric

同時送信型無線ネットワークの物理層に関する研究

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 森川 博之, 東京大学教授 相田 仁, 東京大学教授 廣瀬 明, 東京大学准教授 中山 雅哉, 東京大学准教授 落合 秀也University of Tokyo(東京大学

Evaluation of IEEE 802.11ah Technology for Wireless Sensor Network Applications

We are entering into a new computing technological era where communications are established not just user to user, or user to machine, but also machine to machine (M2M), machine to infrastructure, machine to environment. This then brings out the idea of acquiring data from the environment, process that data and use it to obtain a benefit, and the way to make this happen is by deploying a network of sensors which will provide an application with the desired sensed data. A sensor network is for practical reasons, nowadays considered as a Wireless Sensor Network (WSN). As we move from static web to social networking and furthermore to ubiquitous computing, the amount of wireless devices out there is increasing exponentially. This has triggered a series of challenges for communications technologies as many new requirements need to be addressed. Low-cost, low-power and long-range coverage are the key requirements when designing a WSN. Since the communications subsystem in a WSN is the one dragging most resources, the WSN market is demanding new communication technologies to improve the performance of their current applications, but also to empower innovation by creating new application possibilities. Consequently, a new technology proposal has emerged as a solution to the previously mentioned requirements; the IEEE 802.11ah. This is an amendment to the well-known legacy IEEE 802.11 technologies and promises coverage for up to 1km with at least 100kbps, and support a large amount of stations. This Master’s Thesis offers an insight to this new technology by evaluating its performance through an analytical model which is first developed and then evaluated in MatLab 2014b. A series of performance metrics have been considered in this work with the intention of evaluating its feasibility for WSNs. Different use cases are presented to give an idea of how this new communications standard would perform in real-life scenarios. Based on the obtained results, it is concluded that the standard would perform well when implemented in WSN. But what differentiates the IEEE 802.11ah from its close competitors is the fact that substantial infrastructure using IEEE802.11ah and its amendments already exists, for which the transition to its use seems to be an easy bet. The IEEE 802.11ah is still under development and is expected to be ready for 2016