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

Ph.DDOCTOR OF PHILOSOPH

MedLAN: Compact mobile computing system for wireless information access in emergency hospital wards

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.As the need for faster, safer and more efficient healthcare delivery increases, medical consultants seek new ways of implementing a high quality telemedical system, using innovative technology. Until today, teleconsultation (the most common application of Telemedicine) was performed by transferring the patient from the Accidents and Emergency ward, to a specially equipped room, or by moving large and heavy machinery to the place where the patient resided. Both these solutions were unpractical, uneconomical and potentially dangerous. At the same time wireless networks became increasingly useful in point-of-care areas such as hospitals, because of their ease of use, low cost of installation and increased flexibility. This thesis presents an integrated system called MedLAN dedicated for use inside the A&E hospital wards. Its purpose is to wirelessly support high-quality live video, audio, high-resolution still images and networks support from anywhere there is WLAN coverage. It is capable of transmitting all of the above to a consultant residing either inside or outside the hospital, or even to an external place, thorough the use of the Internet. To implement that, it makes use of the existing IEEE 802.11b wireless technology. Initially, this thesis demonstrates that for specific scenarios (such as when using WLANs), DICOM specifications should be adjusted to accommodate for the reduced WLAN bandwidth. Near lossless compression has been used to send still images through the WLANs and the results have been evaluated by a number of consultants to decide whether they retain their diagnostic value. The thesis further suggests improvements on the existing 802.11b protocol. In particular, as the typical hospital environment suffers from heavy RF reflections, it suggests that an alternative method of modulation (OFDM) can be embedded in the 802.11b hardware to reduce the multipath effect, increase the throughput and thus the video quality sent by the MedLAN system. Finally, realising that the trust between a patient and a doctor is fundamental this thesis proposes a series of simple actions aiming at securing the MedLAN system. Additionally, a concrete security system is suggested, that encapsulates the existing WEP security protocol, over IPSec

GaN-Based Micro-LED Visible Light Communication: Line-of-Sight VLC with Active Tracking and None-Line-of-Sight VLC Demonstration

abstract: Visible light communication (VLC) is the promise of a high data rate wireless network for both indoor and outdoor uses. It competes with 5G radio frequency (RF) system as well. Even though the breakthrough of Gallium Nitride (GaN) based micro-light-emitting-diodes (micro-LEDs) enhances the -3dB modulation bandwidth dramatically from tens of MHz to hundreds of MHz, the optical power onto a fast photo receiver drops exponentially. It determines the signal to noise ratio (SNR) of VLC. For full implementation of the useful high data-rate VLC link enabled by a GaN-based micro-LED, it needs focusing optics and a tracking system. In this dissertation, we demonstrate a novel active on-chip monitoring system for VLC using a GaN-based micro-LED and none-return-to-zero on-off keying (NRZ-OOK) modulation scheme. By this innovative technique without manual focusing, the field of view (FOV) was enlarged to 120° and data rates up to 600 Mbps at a bit error rate (BER) of 2.1×10⁻⁴ were achieved. This work demonstrates the establishment of a VLC physical link. It shows improved communication quality by orders, making it optimized for real communications. This dissertation also gives an experimental demonstration of non-line-of-sight (NLOS) visible light communication (VLC) using a single 80 μm gallium nitride (GaN) based micro-light-emitting diode (micro-LED). IEEE 802.11ac modulation scheme with 80 MHz bandwidth, as an entry level of the fifth generation of Wi-Fi, was employed to use the micro-LED bandwidth efficiently. These practical techniques were successfully utilized to achieve a demonstration of line-of-sight (LOS) VLC at a speed of 433 Mbps, and a bit error rate (BER) of 10⁻⁵ with a free space transmit distance 3.6 m. Besides this, we demonstrated directed NLOS VLC links based on mirror reflections with a data rate of 433 Mbps and a BER of 10⁻⁴. For non-directed NLOS VLC using a print paper as the reflective material, 195 Mbps data rate and a BER of 10⁻⁵ was achieved.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

INJECTION-LOCKING TECHNIQUES FOR MULTI-CHANNEL ENERGY EFFICIENT TRANSMITTER

Ph.DDOCTOR OF PHILOSOPH

Millimeter-wave Communication and Radar Sensing — Opportunities, Challenges, and Solutions

With the development of communication and radar sensing technology, people are able to seek for a more convenient life and better experiences. The fifth generation (5G) mobile network provides high speed communication and internet services with a data rate up to several gigabit per second (Gbps). In addition, 5G offers great opportunities of emerging applications, for example, manufacture automation with the help of precise wireless sensing. For future communication and sensing systems, increasing capacity and accuracy is desired, which can be realized at millimeter-wave spectrum from 30 GHz to 300 GHz with several tens of GHz available bandwidth. Wavelength reduces at higher frequency, this implies more compact transceivers and antennas, and high sensing accuracy and imaging resolution. Challenges arise with these application opportunities when it comes to realizing prototype or demonstrators in practice. This thesis proposes some of the solutions addressing such challenges in a laboratory environment.High data rate millimeter-wave transmission experiments have been demonstrated with the help of advanced instrumentations. These demonstrations show the potential of transceiver chipsets. On the other hand, the real-time communication demonstrations are limited to either low modulation order signals or low symbol rate transmissions. The reason for that is the lack of commercially available high-speed analog-to-digital converters (ADCs); therefore, conventional digital synchronization methods are difficult to implement in real-time systems at very high data rates. In this thesis, two synchronous baseband receivers are proposed with carrier recovery subsystems which only require low-speed ADCs [A][B].Besides synchronization, high-frequency signal generation is also a challenge in millimeter-wave communications. The frequency divider is a critical component of a millimeter-wave frequency synthesizer. Having both wide locking range and high working frequencies is a challenge. In this thesis, a tunable delay gated ring oscillator topology is proposed for dual-mode operation and bandwidth extension [C]. Millimeter-wave radar offers advantages for high accuracy sensing. Traditional millimeter-wave radar with frequency-modulated continuous-wave (FMCW), or continuous-wave (CW), all have their disadvantages. Typically, the FMCW radar cannot share the spectrum with other FMCW radars.\ua0 With limited bandwidth, the number of FMCW radars that could coexist in the same area is limited. CW radars have a limited ambiguous distance of a wavelength. In this thesis, a phase-modulated radar with micrometer accuracy is presented [D]. It is applicable in a multi-radar scenario without occupying more bandwidth, and its ambiguous distance is also much larger than the CW radar. Orthogonal frequency-division multiplexing (OFDM) radar has similar properties. However, its traditional fast calculation method, fast Fourier transform (FFT), limits its measurement accuracy. In this thesis, an accuracy enhancement technique is introduced to increase the measurement accuracy up to the micrometer level [E]

LOW-POWER FREQUENCY SYNTHESIS BASED ON INJECTION LOCKING

Ph.DDOCTOR OF PHILOSOPH

MedLAN : compact mobile computing system for wireless information access in emergency hospital wards

As the need for faster, safer and more efficient healthcare delivery increases, medical consultants seek new ways of implementing a high quality telemedical system, using innovative technology. Until today, teleconsultation (the most common application of Telemedicine) was performed by transferring the patient from the Accidents and Emergency ward, to a specially equipped room, or by moving large and heavy machinery to the place where the patient resided. Both these solutions were unpractical, uneconomical and potentially dangerous. At the same time wireless networks became increasingly useful in point-of-care areas such as hospitals, because of their ease of use, low cost of installation and increased flexibility. This thesis presents an integrated system called MedLAN dedicated for use inside the A;E hospital wards. Its purpose is to wirelessly support high-quality live video, audio, high-resolution still images and networks support from anywhere there is WLAN coverage. It is capable of transmitting all of the above to a consultant residing either inside or outside the hospital, or even to an external place, thorough the use of the Internet. To implement that, it makes use of the existing IEEE 802.11b wireless technology. Initially, this thesis demonstrates that for specific scenarios (such as when using WLANs), DICOM specifications should be adjusted to accommodate for the reduced WLAN bandwidth. Near lossless compression has been used to send still images through the WLANs and the results have been evaluated by a number of consultants to decide whether they retain their diagnostic value. The thesis further suggests improvements on the existing 802.11b protocol. In particular, as the typical hospital environment suffers from heavy RF reflections, it suggests that an alternative method of modulation (OFDM) can be embedded in the 802.11b hardware to reduce the multipath effect, increase the throughput and thus the video quality sent by the MedLAN system. Finally, realising that the trust between a patient and a doctor is fundamental this thesis proposes a series of simple actions aiming at securing the MedLAN system. Additionally, a concrete security system is suggested, that encapsulates the existing WEP security protocol, over IPSec.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

An Analysis of Electromagnetic Interference (EMI) of Ultra Wideband(UWB) and IEEE 802.11A Wireless Local Area Network (WLAN) Employing Orthogonal Frequency Division Multiplexing (OFDM)

Military communications require the rapid deployment of mobile, high-bandwidth systems. These systems must provide anytime, anywhere capabilities with minimal interference to existing military, private, and commercial communications. Ultra Wideband (UWB) technology is being advanced as the next generation radio technology and has the potential to revolutionize indoor wireless communications. The ability of UWB to mitigate multipath fading, provide high-throughput data rates (e.g., greater than 100 Mbps), provide excellent signal penetration (e.g., through walls), and low implementation costs makes it an ideal technology for a wide range of private and public sector applications. Preliminary UWB studies conducted by The Institute for Telecommunications Science (ITS) and the Defense Advanced Research Projects Agency (DARPA) have discovered that potential exists for harmful interference to occur. While these studies have provided initial performance estimates, the interference effects of UWB transmissions on coexisting spectral users are largely unknown. This research characterizes the electromagnetic interference (EMI) effects of UWB on the throughput performance of an IEEE 802.11a ad-hoc network. Radiated measurements in an anechoic chamber investigate interference performance using three modulation schemes (BPSK, BPPM, and OOK) and four pulse repetition frequencies over two Unlicensed National Information Infrastructure (U-NII) channels. Results indicate that OOK and BPPM can degrade throughput performance by up to 20% at lower pulse repetition frequencies (PRFs) in lower U-NII channels. Minimal performance degradation (less than one percent) due to interference was observed for BPSK at the lower PRFs and higher U-NII channels

System design and performance analysis of wireless body area networks

One key solution to provide affordable and proactive healthcare facilities to overcome the fast world population growth and a shortage of medical professionals is through health monitoring systems capable of early disease detection and real-time data transmission leading to considerable improvements in the quality of human life. Wireless body area networks (WBANs) are proposed as promising approaches to providing better mobility and flexibility experience than traditional wired medical systems by using low-power, miniaturised sensors inside, around, or off the human body and are employed to monitor physiological signals. However, the design of reliable and energy efficient in-body communication systems is still a major research challenge since implant devices are characterised by strict requirements on size, energy consumption and safety. Moreover, there is still no agreement regarding QoS support in WBANs. The first part of this work concentrates on the design and performance evaluation of WBAN communication systems involving the ‘in-body to in-body’ and ‘in-body to on-body’ scenarios. The essential step is to derive the statistical WBAN path loss (PL) models, which characterise the signal propagation energy loss transmitting via intra-body region. Moreover, from the point of view of human body safety evaluation, the obtained specific absorption rate (SAR) values are compared with the latest Institute of Electrical and Electronics Engineers (IEEE) 802.15.6 Task Group technical standard and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) safety guidelines. Link budget analysis is then presented using a range of energy-efficient modulation schemes, and the results are given including the transmission distance, data rate and transmitting power in individual sections. On the other hand, major quality of service (QoS) support challenges in WBANs are discussed and investigated. To achieve higher lifetime and lower network energy consumption, different data routing protocol methods, including incremental relaying and the two-relay based routing technique are taken into account. A set of key QoS metrics for linear mathematical models is given along with the related subjective functions. The incremental relaying routing protocol promises significant enhancements in in-body WBAN network lifetime by minimising the overall communication distance while the two-relay based routing method achieves better performance in terms of emergency data transmission and high traffic condition, QoS-aware WBANs design. Moreover, to handle real-time high data transmission applications such as capsule endoscope image transmission, a flexible QoS-aware wireless body area sensor networks (WBASNs) model is proposed and evaluated that can bring novel solutions for a realistic multi-user hospital environment regarding information packet collision probability, manageable numbers of sensor nodes and a wide range of data rates