Development of an Encrypted Wireless System for Body Sensor Network Applications

Wireless body area networks (WBAN), also called wireless body sensor networks (WBSN), consist of a collection of wireless sensor nodes used to monitor and assess various human physiological conditions, which can then be used by healthcare professionals to help them make important healthcare decisions. They can be used to prevent disease, help diagnosis a disease, or manage the symptoms of a disease. An extremely important aspect of WBAN is security to protect a patient\u27s healthcare information, as a hacker could potentially cause fatal harm. Current security measures are implemented in software at the MAC layer and higher, not in the physical layer. Previous research demonstrated a chaotic encryption cipher to add a layer of security in the physical layer. This cipher exploits different properties of the Lorenz chaotic system to encrypt and decrypt digital data. Decryption involved synchronizing two chaotic signals to recover original data by sharing a state between the transmitter and receiver. In this thesis, we further develop the encryption system by implementing wireless capabilities. We use two approaches: the first by using commercially available wireless microcontrollers that communicate using Bluetooth Low Energy, and the second by the design and fabrication of a dual-band low noise amplifier (LNA) that can be used in a receiver for WBANs collecting data from implantable and on-the-body sensors. For the first approach, a custom Bluetooth Low Energy profile was created for streaming the analog encrypted signal, and signal processing was done at the receiver side. For the second approach, the LNA operates at the Medical Implant Communication System (MICS) band and the 915 MHz Industrial, Scientific, and Medical (ISM) band simultaneously through dual-band input and output matching networks

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

Ultra low power wearable sleep diagnostic systems

Sleep disorders are studied using sleep study systems called Polysomnography that records several biophysical parameters during sleep. However, these are bulky and are typically located in a medical facility where patient monitoring is costly and quite inefficient. Home-based portable systems solve these problems to an extent but they record only a minimal number of channels due to limited battery life. To surmount this, wearable sleep system are desired which need to be unobtrusive and have long battery life. In this thesis, a novel sleep system architecture is presented that enables the design of an ultra low power sleep diagnostic system. This architecture is capable of extending the recording time to 120 hours in a wearable system which is an order of magnitude improvement over commercial wearable systems that record for about 12 hours. This architecture has in effect reduced the average power consumption of 5-6 mW per channel to less than 500 uW per channel. This has been achieved by eliminating sampled data architecture, reducing the wireless transmission rate and by moving the sleep scoring to the sensors. Further, ultra low power instrumentation amplifiers have been designed to operate in weak inversion region to support this architecture. A 40 dB chopper-stabilised low power instrumentation amplifiers to process EEG were designed and tested to operate from 1.0 V consuming just 3.1 uW for peak mode operation with DC servo loop. A 50 dB non-EEG amplifier continuous-time bandpass amplifier with a consumption of 400 nW was also fabricated and tested. Both the amplifiers achieved a high CMRR and impedance that are critical for wearable systems. Combining these amplifiers with the novel architecture enables the design of an ultra low power sleep recording system. This reduces the size of the battery required and hence enables a truly wearable system.Open Acces

Design and Implementation of Wireless Point-Of-Care Health Monitoring Systems: Diagnosis For Sleep Disorders and Cardiovascular Diseases

Chronic sleep disorders are present in 40 million people in the United States. More than 25 million people remain undiagnosed and untreated, which accounts for over $22 billion in unnecessary healthcare costs. In addition, another major chronic disease is the heart diseases which cause 23.8% of the deaths in the United States. Thus, there is a need for a low cost, reliable, and ubiquitous patient monitoring system. A remote point-of-care system can satisfy this need by providing real time monitoring of the patient\u27s health condition at remote places. However, the currently available POC systems have some drawbacks; the fixed number of physiological channels and lack of real time monitoring. In this dissertation, several remote POC systems are reported to diagnose sleep disorders and cardiovascular diseases to overcome the drawbacks of the current systems. First, two types of remote POC systems were developed for sleep disorders. One was designed with ZigBee and Wi-Fi network, which provides increase/decrease the number of physiological channels flexibly by using ZigBee star network. It also supports the remote real-time monitoring by extending WPAN to WLAN with combination of two wireless communication topologies, ZigBee and Wi-Fi. The other system was designed with GSM/WCDMA network, which removes the restriction of testing places and provides remote real-time monitoring in the true sense of the word. Second, a fully wearable textile integrated real-time ECG acquisition system for football players was developed to prevent sudden cardiac death. To reduce power consumption, adaptive RF output power control was implemented based on RSSI and the power consumption was reduced up to 20%. Third, as an application of measuring physiological signals, a wireless brain machine interface by using the extracted features of EOG and EEG was implemented to control the movement of a robot. The acceleration/deceleration of the robot is controlled based on the attention level from EEG. The left/right motion of eyeballs of EOG is used to control the direction of the robot. The accuracy rate was about 95%. These kinds of health monitoring systems can reduce the exponentially increasing healthcare costs and cater the most important healthcare needs of the society

Efficient and Interference-Resilient Wireless Connectivity for IoT Applications

With the coming of age of the Internet of Things (IoT), demand on ultra-low power (ULP) and low-cost radios will continue to boost tremendously. The Bluetooth-Low-energy (BLE) standard provides a low power solution to connect IoT nodes with mobile devices, however, the power of maintaining a connection with a reasonable latency remains the limiting factor in defining the lifetime of event-driven BLE devices. BLE radio power consumption is in the milliwatt range and can be duty cycled for average powers around 30μW, but at the expense of long latency. Furthermore, wireless transceivers traditionally perform local oscillator (LO) calibration using an external crystal oscillator (XTAL) that adds significant size and cost to a system. Removing the XTAL enables a true single-chip radio, but an alternate means for calibrating the LO is required. Innovations in both the system architecture and circuits implementation are essential for the design of truly ubiquitous receivers for IoT applications. This research presents two porotypes as back-channel BLE receivers, which have lower power consumption while still being robust in the presents of interference and able to receive back-channel message from BLE compliant transmitters. In addition, the first crystal-less transmitter with symmetric over-the-air clock recovery compliant with the BLE standard using a GFSK-Modulated BLE Packet is presented.PHDElectrical and Computer EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162942/1/abdulalg_1.pd

Reconfigurable Receiver Front-Ends for Advanced Telecommunication Technologies

The exponential growth of converging technologies, including augmented reality, autonomous vehicles, machine-to-machine and machine-to-human interactions, biomedical and environmental sensory systems, and artificial intelligence, is driving the need for robust infrastructural systems capable of handling vast data volumes between end users and service providers. This demand has prompted a significant evolution in wireless communication, with 5G and subsequent generations requiring exponentially improved spectral and energy efficiency compared to their predecessors. Achieving this entails intricate strategies such as advanced digital modulations, broader channel bandwidths, complex spectrum sharing, and carrier aggregation scenarios. A particularly challenging aspect arises in the form of non-contiguous aggregation of up to six carrier components across the frequency range 1 (FR1). This necessitates receiver front-ends to effectively reject out-of-band (OOB) interferences while maintaining high-performance in-band (IB) operation. Reconfigurability becomes pivotal in such dynamic environments, where frequency resource allocation, signal strength, and interference levels continuously change. Software-defined radios (SDRs) and cognitive radios (CRs) emerge as solutions, with direct RF-sampling receivers offering a suitable architecture in which the frequency translation is entirely performed in digital domain to avoid analog mixing issues. Moreover, direct RF- sampling receivers facilitate spectrum observation, which is crucial to identify free zones, and detect interferences. Acoustic and distributed filters offer impressive dynamic range and sharp roll off characteristics, but their bulkiness and lack of electronic adjustment capabilities limit their practicality. Active filters, on the other hand, present opportunities for integration in advanced CMOS technology, addressing size constraints and providing versatile programmability. However, concerns about power consumption, noise generation, and linearity in active filters require careful consideration.This thesis primarily focuses on the design and implementation of a low-voltage, low-power RFFE tailored for direct sampling receivers in 5G FR1 applications. The RFFE consists of a balun low-noise amplifier (LNA), a Q-enhanced filter, and a programmable gain amplifier (PGA). The balun-LNA employs noise cancellation, current reuse, and gm boosting for wideband gain and input impedance matching. Leveraging FD-SOI technology allows for programmable gain and linearity via body biasing. The LNA's operational state ranges between high-performance and high-tolerance modes, which are apt for sensitivityand blocking tests, respectively. The Q-enhanced filter adopts noise-cancelling, current-reuse, and programmable Gm-cells to realize a fourth-order response using two resonators. The fourth-order filter response is achieved by subtracting the individual response of these resonators. Compared to cascaded and magnetically coupled fourth-order filters, this technique maintains the large dynamic range of second-order resonators. Fabricated in 22-nm FD-SOI technology, the RFFE achieves 1%-40% fractional bandwidth (FBW) adjustability from 1.7 GHz to 6.4 GHz, 4.6 dB noise figure (NF) and an OOB third-order intermodulation intercept point (IIP3) of 22 dBm. Furthermore, concerning the implementation uncertainties and potential variations of temperature and supply voltage, design margins have been considered and a hybrid calibration scheme is introduced. A combination of on-chip and off-chip calibration based on noise response is employed to effectively adjust the quality factors, Gm-cells, and resonance frequencies, ensuring desired bandpass response. To optimize and accelerate the calibration process, a reinforcement learning (RL) agent is used.Anticipating future trends, the concept of the Q-enhanced filter extends to a multiple-mode filter for 6G upper mid-band applications. Covering the frequency range from 8 to 20 GHz, this RFFE can be configured as a fourth-order dual-band filter, two bandpass filters (BPFs) with an OOB notch, or a BPF with an IB notch. In cognitive radios, the filter’s transmission zeros can be positioned with respect to the carrier frequencies of interfering signals to yield over 50 dB blocker rejection

Récepteur Sans-Fil à Basse Consommation et à Modulation Mixte FSK-ASK pour les Dispositifs Médicaux

RÉSUMÉ Les émetteurs-récepteurs radiofréquences (RF) offrent le lien de communications le plus commun afin de mettre au point des dispositifs médicaux implantables dédiés aux interfaces homme-machines. La surveillance en continu des paramètres biologiques des patients nécessite un module de communication sans-fil capable de garantir un échange de données rapide, en temps réel, à faible puissance tout en étant implémenté dans un espace physique réduit. La consommation de puissance des dispositifs implantables joue un rôle important dans les durées de vie des batteries qui nécessitent une chirurgie pour leur remplacement, à moins qu’une technique de transfert de puissance sans-fil soit utilisée pour recharger la batterie ou alimenter l’implant a travers les tissus humains. Dans ce projet, nous avons conçu, implémenté et testé un récepteur RF à faible puissance et haut-débit de données opérant entre 902 et 928 MHz qui est la bande industrielle-scientifiquemédicale (Industrial, Scientific and Medical) d’Amérique du Nord. Ce récepteur fait partie d’un système de communication bidirectionnel dédié à l’interface sans-fil des dispositifs électroniques implantables et bénéficie d’une nouvelle technique de conversion de modulation par déplacement de fréquence (FSK) en Modulation par déplacement d’amplitude (ASK). Toutes les phases de conception et d’implémentation de la topologie adoptée pour les récepteurs RF sont survolées et discutées dans cette thèse. Les différents étages de circuits sont conçus selon une étude analytique fondée de la modulation FSK et ASK utilisées, ce qui permettra une amélioration des performances notamment le débit de transmission des données et la consommation de puissance. Tous les circuits sont réalisés de façon à ce que la consommation totale et la surface de silicium à réserver soient le minimum possible. Un oscillateur avec verrouillage par injection (Injection-Looked Oscillator - ILO) de faible puissance est réalisé pour assurer la conversion des signaux ASK en FSK. Une combinaison des avantages des deux architectures de modulation d’amplitude et de fréquence, pour les circuits d’émetteurrécepteur sans fil, a été réalisé avec le système proposé. Un module incluant un récepteur de réveil (Wake up) est ajouté afin d’optimiser la consommation totale du circuit en mettant tous les blocs à l’arrêt. Nous avons réalisé un récepteur de réveil RF compact et à faible coût, permettant de très faible niveaux de consommation d’énergie, une bonne sensibilité et une meilleure tolérance aux interférences. Le design est basé sur une topologie homodyne à détection d’enveloppe permettant une transposition directe du signal RF modulé en amplitude en un signal en bande de base. Cette architecture nécessite une architecture peu encombrante à intégrer qui élimine le problème des fréquences image pour la même topologie avec une modulation de fréquence.---------- ABSTRACT ISM band transceiver using a wake-up bloc for wireless body area networks (WBANs) wearable and implantable medical devices is proposed. The system achieves exceptionally low-power consumption and allows a high-data rate by combining the advantages of Frequency-Shift-Keying (FSK) and Amplitude-Shift- Keying (ASK) modulation techniques. The transceiver employs FSK modulation at a data rate of 8 Mbit/s to establish RF link among the medical device and a control unit. Transmitter (Tx) includes a new efficient FSK modulation scheme which offer up to 20 Mb/s of data-rate and dissipates around 0.084 nJ/b. The design of the proposed oscillator achieves variable frequency from 300 kHz to 8 MHz by adjusting the transistors geometry, the on-chip control signal and the tuning capacitors. In the transmitter path, the high-quality LOs Inand Quadrature-phase (I and Q) outputs are produced using a very low-power fully integrated integer-N frequency synthesizer. The architecture of the receiver is inspired from the super-regenerative receiver (SRR) topology which can be used to design a transceiver that is suitable for ASK modulation. In fact, this architecture is based mainly on envelope detection scheme which remove the need to process the carrier phase to reduce the complexity of integrated design. It has been shown too, that the envelope detection scheme is more robust to phase noise than the coherent scheme. The integrated receiver uses on a new FSK-to-ASK conversion technique. The conversion feature that we adopt in the main receiver design is based on the fact that the incident frequency of converter could be differentiated by the amplitude of output signal, which conducts to the frequency-to-amplitude conversion. Thanks to the injection locking oscillator (ILO). the new design of converter is located between the LNA as first part and the envelope detector as second part to benefit from the injection-locking isolation. On-Off-keying (OOK) fully passive wake-up circuit (WuRx) with energy harvesting from Radio Frequency (RF) link is used to optimize the power issipation of the RF transceiver in order to meet the low power requirement. The WuRx operates at the ISM 902–928 MHz. A high efficiency differential rectifier behaves as voltage multiplier. It generates the envelope of the input signal and provides the supply voltage for the rest of blocks including a low-power comparator and reference generators

Reliable and Energy Efficient Network Protocols for Wireless Body Area Networks

In a wireless Body Area Network (WBAN) various sensors are attached on clothing, on the body or are even implanted under the skin. The wireless nature of the network and the wide variety of sensors offers numerous new, practical and innovative applications. A motivating example can be found in the world of health monitoring. The sensors of the WBAN measure for example the heartbeat, the body temperature or record a prolonged electrocardiogram. Using a WBAN, the patient experiences a greater physical mobility and is no longer compelled to stay in a hospital. A WBAN imposes the networks some strict and specific requirements. The devices are tiny, leaving only limited space for a battery. It is therefore of uttermost importance to restrict the energy consumption in the network. A possible solution is the development of energy efficient protocols that regulate the communication between the radios. Further, it is also important to consider the reliability of the communication. The data sent contains medical information and one has to make sure that it is correctly received at the personal device. It is not allowed that a critical message gets lost. In addition, a WBAN has to support the heterogeneity of its devices. This thesis focuses on the development of energy efficient and reliable network protocols for WBANs. Considered solutions are the use of multi-hop communication and the improved interaction between the different network layers. Mechanisms to reduce the energy consumption and to grade up the reliability of the communication are presented. In a first step, the physical layer of the communication near the human body is studied and investigated. The probability of a connection between two nodes on the body is modeled and used to investigate which network topologies can be considered as the most energy efficient and reliable. Next, MOFBAN, a lightweight framework for network architecture is presented. Finally, CICADA is presented: a new cross layer protocol for WBANs that both handles channel medium access and routing

Congestion control mechanism for sensor-cloud Infrastructure

 This thesis has developed a sensor-Cloud system that integrates WBANs with Cloud computing to enable real-time sensor data collection, storage, processing, sharing and management. As the main contribution of this study, a congestion detection and control protocol is proposed to ensure acceptable data flows are maintained during the network lifetime