Antennas and propagation for body area networks at 60 GHZ

208 Pages·2014·5.74 MB·English

by  Xianyue Wu

ANTENNAS AND PROPAGATION FOR
BODY AREA NETWORKS AT 60 GHZ
by
XIANYUE WU
A thesis submitted to
the University of Birmingham
for the degree of
Doctor of Philosophy
School of Electronic, Electrical & Computer Engineering
College of Engineering and Physical Sciences
University of Birmingham
September 2013
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Abstract
The advent of wireless body area networks (WBANs) and their use in a wide range of
applications from consumer electronics to military purposes, dictates the need to investi-
gate to the behaviour of antennas and wave propagation on the body in depth. Although
this area has been extensively studied in the past decade, some issues are still not satis-
factorily solved for communication systems for WBANs at ISM bands and UWB such as
compact and high efficiency antenna design, privacy and security, interference mitigation
and achieving high data rates. This thesis proposed an alternative wireless solution for
body area networks by adopting 60 GHz radio. On-body channels at 60 GHz have been
characterised using monopole and horn antennas. Horn antennas achieve significantly
improved path gain in the stable channels but are susceptible to shadowing in the mo-
bile channels due to body movements. However, interference mitigation and covertness
for 60 GHz WBANs at the physical layer are improved due to high attenuation of 60
GHz signals. Significant increase of carrier-to-interference ratio is observed for 60 GHz
WBANs compared to 2.45 GHz. A model of estimating the maximum detection distance
at a threshold probability for detecting a WBAN wearing soldier in a battlefield is pro-
posed. Fixed-beam directional antennas and reconfigurable antennas are designed for 60
GHz WBANs and channel measurements using these antennas are conducted. Results
show beam-reconfigurability of the antenna improves the link performance compared to
fixed-beam antennas at 60 GHz.
To My Parents
Acknowledgements
My first debt of gratitude must go to my supervisors Professor Peter S. Hall and Dr.
Costas Constantinou. They patiently provided the vision, encouragement and advice
necessary for me to proceed through the doctoral program and complete my thesis. I
want to thank them for their unflagging encouragement and serving as role models to me
as a junior member of academia.
I had a great opportunity to visit the University of Virginia as a part of my PhD. The
whole experience was unique and I would like to acknowledge Professor John Lach for his
great advice.
I would like to thank examiners of my thesis, Professor William Scanlon and Dr. Alexan-
dros Feresidis, for their time and feedback on my work.
I would also like to express my deep gratitude to my colleague, Dr. Yuriy I. Nechayev,
who has been very supportive and generous in sharing his knowledge. I am very greatful
to Mr. Alan Yates for providing all the technical support. Special thanks to my other
brilliant colleagues and very nice friends, Dr. Zhengpeng Wang, Dr. Lida Akhoonzadeh-
Asl, Dr. Mohammad Hmaid, Dr. Zhenhua Hu, Mr. Xiao Li, Mr. Philip Asare from the
University of Virginia and Dr. Nacer Chahat from the University of Renne 1 for their
kind help and friendship.
I also want to thank Engineering and Physical Sciences Research Council for providing
me the opportunity and partial funding to pursue my PhD degree.
Last but not least, I would like to thank my beloved parents, for their endless support,
love and understanding.
Acronyms
AFD Average Fade Duration
BAN Body Area Network
BSN Body Sensor Network
CDF Cumulative Distribution Function
CIR Carrier to Interference Ratio
DOA Direction Of Arrival
DRA Dielectric Resonator Antenna
DSSS Direct Sequence Spread Spectrum
EBG Electromagnetic Band Gap
ECG Electrocardiography
EEG Electroencephalography
EMG Electromyography
FCC Federal Communications Commission
FDA Food and Drug Administration
FDTD Finite Difference Time Domain
FHSS Frequency-Hopping Spread Spectrum
ISM Industrial Scientific and Medical
LCR Level Crossing Rate
LOS Line Of Sight
LTCC Low Temperature Co-fired Ceramic
MBAN Medical Body Area Network
MEMS Microelectromechanical System
MICS Medical Implant Communication Service
NBI Narrowband Interference
NLOS Non Line Of Sight
OMT Orthomode Transducer
PCB Printed Circuit Board
pdf Probability Density Function
PDP Power Delay Profile
PIFA Planar Inverted-F Antenna
ROC Receiver Operating Characteristic
RSSI Received Signal Strength Indicator
RMS Root Mean Square
SAR Radiation Absorption Rate
SINR Signal to Interference plus Noise Ratio
SIW Substrate Integrated Waveguide
SNR Signal to Noise Ratio
UWB Ultra-wide Band
VNA Vector Network Analyser
WBAN Wireless Body Area Network
WLAN Wireless Local Area Network
Contents
1 Introduction 1
1.1 Introduction to Body Area Networks . . . . . . . . . . . . . . . . . . . . . 1
1.2 Technological Issues on Body Area Networks . . . . . . . . . . . . . . . . . 4
1.3 Why Study Antennas and Propagation? . . . . . . . . . . . . . . . . . . . 6
1.4 Summary of the Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.5 Layout of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2 Overview of Antennas and Propagation for WBANs 10
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2 Basic Concepts and Theories . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2.1 Cumulative Distribution Function . . . . . . . . . . . . . . . . . . . 11
2.2.2 Level Crossing Rate and Average Fade Duration . . . . . . . . . . . 11
2.2.3 Two-port Network and S-Parameters . . . . . . . . . . . . . . . . . 13
2.2.4 Path Loss and Path Gain . . . . . . . . . . . . . . . . . . . . . . . 14
2.3 Radio Channel Characterisation for WBANs . . . . . . . . . . . . . . . . . 15
2.3.1 Channel measurements and empirical models . . . . . . . . . . . . . 16
2.3.2 Simulations and human phantoms . . . . . . . . . . . . . . . . . . . 21
2.3.3 Characterisation of Dynamic Body Effects . . . . . . . . . . . . . . 23
2.4 Wearable Antenna Design . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.4.1 On-body conventional antennas . . . . . . . . . . . . . . . . . . . . 25
2.4.2 Textile antennas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.5 Interference and Covertness for WBANs . . . . . . . . . . . . . . . . . . . 29
2.5.1 Narrowband interference . . . . . . . . . . . . . . . . . . . . . . . . 30
2.5.2 UWB interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3 Introduction to 60 GHz Wireless Body Area Networks 35
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.2 Benefits and challenges for 60 GHz WBANs . . . . . . . . . . . . . . . . . 37
3.3 60 GHz Wireless Communications . . . . . . . . . . . . . . . . . . . . . . . 38
3.4 Review of 60 GHz Antennas . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4 Measurement Methods 43
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43