Architecture for ultra-low power multi-channel transmitters for Body Area Networks using RF resonators

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 99-103).Body Area Networks (BANs) are gaining prominence for their use in medical and sports monitoring. This thesis develops the specifications of a ultra-low power 2.4GHz transmitter for use in a Body Area Networks, taking advantage of the asymmetric energy constraints on the sensor node and the basestation. The specifications include low transmit output powers, around -10dBm, low startup time, simple modulation schemes of OOK, FSK and BPSK and high datarates of 1Mbps. An architecture that is suited for the unique requirements of transmitters in these BANs is developed. RF Resonators, and in particular Film Bulk Acoustic Wave Resonators (FBARs) are explored as carrier frequency generators since they provide stable frequencies without the need for PLLs. The frequency of oscillation is directly modulated to generate FSK. Since these oscillators have low tuning range, the architecture uses multiple resonators to define the center frequencies of the multiple channels. A scalable scheme that uses a resonant buffer is developed to multiplex the oscillators' outputs to the Power Amplifier (PA). The buffer is also capable of generating BPSK signals. Finally a PA optimized for efficiently delivering the low output powers required in BANs is developed. A tunable matching network in the PA also enables pulse-shaping for spectrally efficient modulation. A prototype transmitter supporting 3 FBAR-oscillator channels in the 2.4GHz ISM band was designed in a 65nm CMOS process. It operates from a 0.7V supply for the RF portion and 1V for the digital section. The transmitter achieves 1Mbps FSK, up to 10Mbps for OOK and BPSK without pulse shaping and 1Mbps for OOK and BPSK with pulse shaping. The power amplifier has an efficiency of up to 43% and outputs between -15dBm and -7.5dBm onto a 50Q antenna. Overall, the transmitter achieves an efficiency of upto 26% and energy per bit of 483pJ/bit at 1Mbps.by Arun Paidimarri.S.M

Bioelectronic Sensor Nodes for Internet of Bodies

Energy-efficient sensing with Physically-secure communication for bio-sensors on, around and within the Human Body is a major area of research today for development of low-cost healthcare, enabling continuous monitoring and/or secure, perpetual operation. These devices, when used as a network of nodes form the Internet of Bodies (IoB), which poses certain challenges including stringent resource constraints (power/area/computation/memory), simultaneous sensing and communication, and security vulnerabilities as evidenced by the DHS and FDA advisories. One other major challenge is to find an efficient on-body energy harvesting method to support the sensing, communication, and security sub-modules. Due to the limitations in the harvested amount of energy, we require reduction of energy consumed per unit information, making the use of in-sensor analytics/processing imperative. In this paper, we review the challenges and opportunities in low-power sensing, processing and communication, with possible powering modalities for future bio-sensor nodes. Specifically, we analyze, compare and contrast (a) different sensing mechanisms such as voltage/current domain vs time-domain, (b) low-power, secure communication modalities including wireless techniques and human-body communication, and (c) different powering techniques for both wearable devices and implants.Comment: 30 pages, 5 Figures. This is a pre-print version of the article which has been accepted for Publication in Volume 25 of the Annual Review of Biomedical Engineering (2023). Only Personal Use is Permitte

Channel modeling and characterization for VLC-based medical body sensor networks: trends and challenges

Optical Wireless Communication (OWC) refers to transmission in unguided propagation media through the use of optical carriers, i.e., visible, Infrared (IR), and Ultraviolet (UV) bands. In this paper, we focus on indoor Visible Light Communication (VLC)-based Medical Body Sensor Networks (MBSNs) which allow the Light Emitting Diodes (LEDs) to communicate between on-body sensors/subdermal implants and on-body central hubs/monitoring devices while also serving as a luminaire. Since the Quality-of-Service (QoS) of the communication systems depends heavily on realistic channel modeling and characterization, this paper aims at presenting an up-to-date survey of works on channel modeling activities for MBSNs. The first part reviews existing IR-based MBSNs channel models based on which VLC channel models are derived. The second part of this review provides details on existing VLC-based MBSNs channel models according to the mobility of the MBSNs on the patient’s body. We also present a realistic channel modeling approach called site-specific ray tracing that considers the skin tissue for the MBSNs channel modeling for realistic hospital scenarios.Scientific Research Projects (BAP) (Grant Number: 20A204)Publisher's Versio

Application-Specific Things Architectures for IoT-Based Smart Healthcare Solutions

Human body is a complex system organized at different levels such as cells, tissues and organs, which contributes to 11 important organ systems. The functional efficiency of this complex system is evaluated as health. Traditional healthcare is unable to accommodate everyone's need due to the ever-increasing population and medical costs. With advancements in technology and medical research, traditional healthcare applications are shaping into smart healthcare solutions. Smart healthcare helps in continuously monitoring our body parameters, which helps in keeping people health-aware. It provides the ability for remote assistance, which helps in utilizing the available resources to maximum potential. The backbone of smart healthcare solutions is Internet of Things (IoT) which increases the computing capacity of the real-world components by using cloud-based solutions. The basic elements of these IoT based smart healthcare solutions are called "things." Things are simple sensors or actuators, which have the capacity to wirelessly connect with each other and to the internet. The research for this dissertation aims in developing architectures for these things, focusing on IoT-based smart healthcare solutions. The core for this dissertation is to contribute to the research in smart healthcare by identifying applications which can be monitored remotely. For this, application-specific thing architectures were proposed based on monitoring a specific body parameter; monitoring physical health for family and friends; and optimizing the power budget of IoT body sensor network using human body communications. The experimental results show promising scope towards improving the quality of life, through needle-less and cost-effective smart healthcare solutions

Enhancing the efficiency of electricity utilization through home energy management systems within the smart grid framework

The concept behind smart grids is the aggregation of “intelligence” into the grid, whether through communication systems technologies that allow broadcast/data reception in real-time, or through monitoring and systems control in an autonomous way. With respect to the technological advancements, in recent years there has been a significant increment in devices and new strategies for the implementation of smart buildings/homes, due to the growing awareness of society in relation to environmental concerns and higher energy costs, so that energy efficiency improvements can provide real gains within modern society. In this perspective, the end-users are seen as active players with the ability to manage their energy resources, for example, microproduction units, domestic loads, electric vehicles and their participation in demand response events. This thesis is focused on identifying application areas where such technologies could bring benefits for their applicability, such as the case of wireless networks, considering the positive and negative points of each protocol available in the market. Moreover, this thesis provides an evaluation of dynamic prices of electricity and peak power, using as an example a system with electric vehicles and energy storage, supported by mixed-integer linear programming, within residential energy management. This thesis will also develop a power measuring prototype designed to process and determine the main electrical measurements and quantify the electrical load connected to a low voltage alternating current system. Finally, two cases studies are proposed regarding the application of model predictive control and thermal regulation for domestic applications with cooling requirements, allowing to minimize energy consumption, considering the restrictions of demand, load and acclimatization in the system

Data fusion of relative movement in fast, repetitive-action sports using body wireless area networks

Rowing is an intensive, all-body sport, where bad technique can lead to injury. Crew cohesion, particularly timing, is vital to the performance of the boat. The coaching process, and injury prevention, could be enhanced if data relating to the movement of the oarsmen could be collected, without hindrance to the oarsmen, during on-water training. Literature until recently has concentrated upon boat-centric measurement. Advances in wireless technology have made feasible the collection of data from multiple physically separate sites, including on-body. After analysis of candidate radio standards, a Zigbee wireless Body Sensor Network (BSN) was designed and developed to synchronously collect data from several sensors across the wireless BSN. By synchronising sensor nodes via scheduled synchronising messages from the central coordinating node, synchronisation within 0.79msec ±0.39ms was achieved. Minimisation of the on-time of the sensor node radios currently extends the battery life by a factor of 5. Acceleration and muscle activity data collected using the wireless BSN was compared to data synchronously collected using proven motion analysis techniques to validate the system. Synchronous muscle activity data was collected via the wireless BSN from several muscles during both land-based and on-water rowing and the results compared. The system was proven to facilitate the identification of bad rowing technique, as well as differences in muscle recruitment between land- and water-based rowing. Data collection from a rowing crew was also demonstrated, and their muscle activity and inter-crew timing analysed. With an additional sensor node upon the boat, it is possible to correlate acceleration and muscle activity from the oarsman with acceleration of the boat itself. A novel, power-optimised wireless sensor network has been designed and demonstrated to facilitate on-water rowing monitoring that can be extended beyond single oarsman measurements to analyse the interaction and cohesion of a crew and their impact upon boat performance

Low-Power High-Data-Rate Transmitter Design for Biomedical Application

Ph.DDOCTOR OF PHILOSOPH

Contribuições às redes de comunicação pelo corpo humano: Modelagem de canal e projeto de um transceptor integrado

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia Elétrica, Florianópolis, 2017.As redes de sensores sem fio (WSN) são uma tecnologia importante e consolidada em diversas áreas, desde monitoramento industrial à assistência médica, contudo, muitos desafios ainda persistem. Um destes desafios é o consumo de potência dos nós da rede, que é um fator limitante para criação de nós duráveis, desejáveis sobretudo em nós vestíveis e implantáveis. Em geral, em um nó sem fio, o bloco de comunicação apresenta o maior consumo do dispositivo. Para reduzir o consumo e aumentar a vida útil dos nós, além da otimização do projeto dos circuitos e da rede, novos métodos de comunicação podem ser utilizados. Neste sentido, a comunicação pelo corpo humano (HBC) tem atraído interesse tanto da academia quando da indústria como uma alternativa para implementar um subtipo das WSN, as redes sem fio corporais (WBAN). No HBC, o corpo humano é utilizado como o canal de comunicação. Um aspecto importante do desenvolvimento desta tecnologia é a caracterização do canal para permitir o projeto adequado dos transceptores. Com este objetivo, neste trabalho foram realizadas várias medições do canal HBC. A análise dos resultados experimentais, contudo, permitiu identificar uma influência não desprezível no perfil de frequência do canal e nos níveis de atenuação medidos. Estes efeitos, em geral, não são reconhecidos ou corrigidos por outros trabalhos encontrados na bibliografia, principalmente poque não podem ser removidos por métodos comuns de calibração ou de-embedding. Para entender e explicar os resultados de medição, são propostas uma metodologia para identificação das partes que compõem o canal e um modelo estendido para o canal, que inclui modelos para os acessórios de testes. A metodologia de identificação auxilia a diferenciação e a modelagem dos componentes essenciais do canal, que é feita por meio de modelos baseados em circuitos concentrados e distribuídos e permite identificar o comportamento esperado do canal primário real. O modelo estendido proposto é verificado com medições do canal e apresenta uma boa correlação com as medições. Este modelo é então utilizado no projeto de um transceptor HBC integrado, que buscou o baixo consumo e a capacidade de operação em banda larga, com múltiplos canais cobrindo a faixa de frequências entre 10-100 MHz do canal de comunicação. Com estes objetivos, projetou-se um transmissor BFSK de modulação direta, composto por um oscilador current starved controlado por tensão e um driver de saída, para acoplamento do sinal ao canal. O receptor é baseado na técnica de injection locking e emprega a conversão frequência-fase para demodulação banda larga do sinal, sendo composto por um amplificador de entrada push-pull, um oscilador current starved com injection locking controlado por tensão, um detector de fase tristate, um filtro RC e um conversor analógico digital. O transceptor foi projetado e fabricado em tecnologia CMOS 130 nm e possui cinco canais de comunicação na faixa entre 10-100 MHz, apresenta uma taxa de dados de 2 Mbps e uma taxa de erro de bit de 0,5.10-3 para sinais de -35,8 dBm no canal HBC. O consumo do transmissor é 6,6 mW e do receptor é 1,68 mW, alcançando a eficiência de comunicação de 3,3 nJ/bit e 0,84 nJ/bit, respectivamente, para uma tensão de alimentação de 1,2 V.Abstract : Wireless sensor networks (WSN) are a consolidated and important technology in several areas, from industrial monitoring to health care, however, many issues are open to be solved. One of the greatest challenges lies on the power consumption of the network nodes, which is a limiting factor for durable wearable and implantable devices. In most cases the communication block is the most power hungry section in the wireless node. To reduce power consumption and increase the node's lifetime, besides optimizing the transceiver hardware and network design, alternative communication methods can be employed. In this regard, Human body communication (HBC) has attracted growing interest from both academy and industry as an alternative to implement Wireless Body Area Networks (WBAN). In HBC the human body is used as the communication channel. A very important aspect concerning the development of the HBC technology is the characterization of the channel for proper transceiver design. With this in mind, this work presents various channel measurements performed in the HBC channel to evaluate its behavior. From the measurement results, it is identified that the test fixtures affect the HBC measurements, changing the channel frequency profile and the channel attenuation levels. These issues were not identified or corrected in the literature studied, mostly because they cannot be removed by common calibration and de-embedding methods. To understand and explain the measured channel response, an channel identification methodology and an extended channel model, which includes the test fixtures models are proposed. The channel identification methodology aides the correct identification and modeling of the essential channel components using distributed and lumped circuit representations that provide a useful insight into the expected primary channel behavior. The proposed extended channel model is tested against channel measurement results and good correlation with experiments is obtained. The proposed primary channel model is then used for a more reliable transceiver design, which focused in lower power consumption and multi-band operation in the 10-100 MHz range of the channel. With these requirements, in the integrated HBC transmitter a direct modulation BFSk architecture is used, consisting of a voltage controlled current starved oscillator and an output driver, for coupling the signal to the channel. The HBC receiver is based on injection locking technique and does broadband demodulation with frequency-to-phase conversion. The receiver consists of a push-pull input amplifier, a voltage-controlled current starved oscillator, a tristate phase detector, a RC filter and analog to digital converter. The transceiver was designed and fabricated in CMOS 130 nm technology and has five communication channels in the range of 10-100 MHz, a data rate of 2 Mbps and a bit error rate of 0.5x10-3 for -35,8 dBm signals on the HBC channel. The transmitter and receiver power consumption are 6.6 mW and 1.68 mW, respectivelly, which enables a communication efficiency of 3.3 nJ/bit and 0.84 nJ/bit with a 1.2 V supply voltage