| dc.description.abstract | The emergence of Body-centric Wireless Communication (BCWC) integrated with
textile-based antenna in various applications has open door to a new dimension of ergonomic body-worn communications. In such environmental settings, human body characteristics with different dimensions and tissue properties, and dynamic movements of the body are the major factors in influencing the on-body radio propagation channel characteristics. The presence of metallic objects worn on their bodies, such as spectacles, watches, belt-buckles, and jewelry is another concern that may affect the
operability of BCWC in terms of reliability and efficiency of the communication link.
Additionally, due to the nature of human body that involves in various movements
makes this radio channel more difficult to be characterized coupled with the presence of
metallic accessories. Thus, a thorough experimental investigation of the influence of onbody worn metallic items on the on-body propagation channel considering static and
dynamic body motion is required in further facilitating a reliable wireless
communication link. The thesis focuses on the characterization of the narrowband (2.45
GHz) on-body radio propagation channel considering metallic accessories, i.e.,
spectacles and watches by utilizing wearable textile monopole antennas. The path loss
of the on-body radio channel is characterized explicitly taking into account the body size of the subjects. The results show that the path loss exponent tends to be lower for full-rimmed spectacles for normal subjects compared to underweight and overweight subjects, by 1.4% in static scenario. For metallic loop-like accessories, the results
indicate that for normal subjects, there is more influence in path loss exponent value, up
to 11.4%, compared to underweight and overweight subjects. Furthermore, our finding
indicated that there was statistical significant difference between with and without
metallic watch (tungsten) towards subject specificity effects for both body and arm
movements at several on-body links which were closer to the metallic watch (P<0.05,
ANOVA test). The path loss decreases when the reception terminal is positioned very
close to the metallic loop-like accessories. If such loop-like metallic accessory along
with subject specificity is not being appropriately considered when designing the radio
channel, a reliable body-centric wireless system may be degraded. The investigations
are extended further to study the possible effect of 2.45 GHz wireless body area
network radio frequency (WBAN RF) radiation on the neurophysiological
(electroencephalogram (EEG)), cognitive performance, well-being and physiological
parameters of adults, emitted by wearable planar textile antenna. The results
demonstrate that there is no statistically significant difference between the active
exposure and Sham exposure on EEG, cognitive performance, well-being, and
physiological parameters effects (P‘s>0.05). In addition, the effects of WBAN exposure
are experimentally investigated in relation to different antennas topologies. The results
reveal that there is significant resting EEG power alteration in frontal and temporal
regions when exposed to short-term textile patch radiation compared to textile
monopole radiation between left and right hemispheres of the brain (P<0.001).
However, there is no statistically significant difference between textile patch and textile monopole exposures on well-being, body temperature, blood pressure, and heart rate of
adults (P‘s>0.05). This research has led to a better understanding of static and dynamic
on-body propagation channels of the effects of metallic accessories on subject
specificity as well as its exposure effects on the neurophysiological and behavioral of
adults. | en_US |
