1,532 research outputs found
Statistical Modeling of Ultrawideband Body-Centric Wireless Channels Considering Room Volume
This paper presents the results of a statistical modeling of onbody ultrawideband (UWB) radio channels for wireless body area network (WBAN) applications. Measurements were conducted in five different rooms. A measured delay profile can be divided into two domains; in the first domain (04 ns) has multipath components that are dominant and dependent on room volume. The first domain was modeled with a conventional power decay law model, and the second domain with a modified Saleh-Valenzuela model considering the room volume. Realizations of the impulse responses are presented based on the composite model and compared with the measured average power delay profiles
Ultrawideband Technology for Medical In-Body Sensor Networks: An Overview of the Human Body as a Propagation Medium, Phantoms, and Approaches for Propagation Analysis
[EN] An in-body sensor network is that in which at least one of the sensors is located inside the human body. Such wireless in-body sensors are used mainly in medical applications, collecting and monitoring important parameters for health and disease treatment. IEEE Standard 802.15.6-2012 for wireless body area networks (WBANs) considers in-body communications in the Medical Implant Communications Service (MICS) band. Nevertheless, high-data-rate communications are not feasible at the MICS band because of its narrow occupied bandwidth. In this framework, ultrawideband (UWB) systems have emerged as a potential solution for in-body highdata-rate communications because of their miniaturization capabilities and low power consumption.This work was supported by the Programa de Ayudas de Investigación y Desarrollo (PAID-01-16) at the Universitat Politècnica de València, Spain; by the Ministerio de Economía y Competitividad, Spain (TEC2014-60258-C2-1-R); and by the European FEDER funds. It was also funded by the European Union’s H2020:MSCA:ITN program for the Wireless In-Body Environ-ment Communication–WiBEC project under grant 675353.Garcia-Pardo, C.; Andreu-Estellés, C.; Fornés Leal, A.; Castelló-Palacios, S.; Pérez-Simbor, S.; Barbi, M.; Vallés Lluch, A.... (2018). Ultrawideband Technology for Medical In-Body Sensor Networks: An Overview of the Human Body as a Propagation Medium, Phantoms, and Approaches for Propagation Analysis. IEEE Antennas and Propagation Magazine. 60(3):19-33. https://doi.org/10.1109/MAP.2018.2818458S193360
Modelling and characterisation of antennas and propagation for body-centric wireless communication
PhDBody-Centric Wireless Communication (BCWC) is a central point in the development
of fourth generation mobile communications. The continuous miniaturisation of sensors,
in addition to the advancement in wearable electronics, embedded software, digital
signal processing and biomedical technologies, have led to a new concept of usercentric
networks, where devices can be carried in the user’s pockets, attached to the
user’s body or even implanted.
Body-centric wireless networks take their place within the personal area networks,
body area networks and body sensor networks which are all emerging technologies
that have a broad range of applications such as healthcare and personal entertainment.
The major difference between BCWC and conventional wireless systems is the
radio channel over which the communication takes place. The human body is a hostile
environment from radio propagation perspective and it is therefore important to understand
and characterise the effect of the human body on the antenna elements, the
radio channel parameters and hence the system performance. This is presented and
highlighted in the thesis through a combination of experimental and electromagnetic
numerical investigations, with a particular emphasis to the numerical analysis based
on the finite-difference time-domain technique.
The presented research work encapsulates the characteristics of the narrowband
(2.4 GHz) and ultra wide-band (3-10 GHz) on-body radio channels with respect to
different digital phantoms, body postures, and antenna types hence highlighting the
effect of subject-specific modelling, static and dynamic environments and antenna performance
on the overall body-centric network. The investigations covered extend further
to include in-body communications where the radio channel for telemetry with
medical implants is also analysed by considering the effect of different digital phantoms
on the radio channel characteristics. The study supports the significance of developing
powerful and reliable numerical modelling to be used in conjunction with measurement campaigns for a comprehensive understanding of the radio channel in
body-centric wireless communication. It also emphasises the importance of considering
subject-specific electromagnetic modelling to provide a reliable prediction of the
network performance
Development of a Real-time Ultra-wideband See Through Wall Imaging Radar System
Ultra-Wideband (UWB) See-Through-Wall (STW) technology has emerged as a musthave enabling technology by both the military and commercial sectors. As a pioneer in this area, we have led the research in addressing many of the fundamental STW questions. This dissertation is to investigate and resolve a few hurdles in advancing this technology, and produce a realizable high performance STW platform system, which will aid the STW community to find the ultimate answer through experimental and theoretical work. The architectures of a realizable STW imaging system are thoroughly examined and studied. We present both a conceptual system based on RF instruments and a standalone real-time system based on custom design, which utilize reconfigurable design architecture and allows scaling down/up to a desired UWB operating frequency with little difficulty. The systems will serve as a high performance platform for STW study and other related UWB applications. Along the way to a complete STW system, we have developed a simplified transmission line model for wall characteristic prediction; we have developed a scalable synthetic aperture array including both the RF part and the switch control/synchronization part; we have proposed a cost-effective and efficient UWB data acquisition method for real-time STW application based on equivalent-time sampling method. The measurement results reported here include static image formation and tracking moveable targets behind the wall. Even though digital signal processing to generate radar images is not the focus of this research, simple methods for image formation have been implemented and results are very encouraging
Experimental Path Loss Models for In-Body Communications Within 2.36-2.5 GHz
"(c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works."Biomedical implantable sensors transmitting a variety
of physiological signals have been proven very useful in the
management of chronic diseases. Currently, the vast majority of
these in-body wireless sensors communicate in frequencies below
1 GHz. Although the radio propagation losses through biological
tissues may be lower in such frequencies, e.g., the medical implant
communication services band of 402 to 405 MHz, the maximal
channel bandwidths allowed therein constrain the implantable
devices to low data rate transmissions. Novel and more sophisticated
wireless in-body sensors and actuators may require higher
data rate communication interfaces. Therefore, the radio spectrum
above 1 GHz for the use of wearable medical sensing applications
should be considered for in-body applications too. Wider channel
bandwidths and smaller antenna sizes may be obtained in frequency
bands above 1 GHz at the expense of larger propagation
losses. Therefore, in this paper, we present a phantom-based radio
propagation study for the frequency bands of 2360 to 2400 MHz,
which has been set aside for wearable body area network nodes,
and the industrial, scientific, medical band of 2400 to 2483.5 MHz.
Three different channel scenarios were considered for the propagation
measurements: in-body to in-body, in-body to on-body, and
in-body to off-body.We provide for the first time path loss formulas
for all these cases.Chavez-Santiago, R.; García Pardo, C.; Fornés Leal, A.; Vallés Lluch, A.; Vermeeren, G.; Joseph, W.; Balasingham, I.... (2015). Experimental Path Loss Models for In-Body Communications Within 2.36-2.5 GHz. IEEE Journal of Biomedical and Health Informatics. 19(3):930-937. doi:10.1109/JBHI.2015.2418757S93093719
1-D broadside-radiating leaky-wave antenna based on a numerically synthesized impedance surface
A newly-developed deterministic numerical technique for the automated design of metasurface antennas is applied here for the first time to the design of a 1-D printed Leaky-Wave Antenna (LWA) for broadside radiation. The surface impedance synthesis process does not require any a priori knowledge on the impedance pattern, and starts from a mask constraint on the desired far-field and practical bounds on the unit cell impedance values. The designed reactance surface for broadside radiation exhibits a non conventional patterning; this highlights the merit of using an automated design process for a design well known to be challenging for analytical methods. The antenna is physically implemented with an array of metal strips with varying gap widths and simulation results show very good agreement with the predicted performance
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
- …