K. C. Sarma

Experimental determination of path loss and delay dispersion parameters for on-body UWB WBAN channel

UWB (Ultra-Wideband) radio technology is an excellent candidate for WBAN (Wireless Body Area Network) applications due to its inherent features like low level of radiated power, robustness against multipath and compact in size. Mathematical modelling of the channel under consideration and experimental determination of its parameters are prerequisites for the development of a reliable communication system. UWB channel characteristics in WBAN scenarios are significantly different from the typical indoor channels. This paper reports the experimental results for path loss, shadow fading and delay dispersion parameters of on-body UWB WBAN channel. Channel measurements are performed in frequency domain using a VNA (Vector Network Analyzer) in a laboratory environment for the frequency band of 3.1-10.6 GHz. Both LOS (line-of-sight) and NLOS (non-line-of-sight) scenarios of WBAN channel are considered for measurement. The path loss, shadow fading and delay dispersion parameters are statistically analysed and reported in this paper. Variation of the parameters with the size of the body is investigated and reported.

Path loss variation of on-body UWB channel in the frequency bands of IEEE 802.15.6 standard.

The wireless body area network (WBAN) has gaining tremendous attention among researchers and academicians for its envisioned applications in healthcare service. Ultra wideband (UWB) radio technology is considered as excellent air interface for communication among body area network devices. Characterisation and modelling of channel parameters are utmost prerequisite for the development of reliable communication system. The path loss of on-body UWB channel for each frequency band defined in IEEE 802.15.6 standard is experimentally determined. The parameters of path loss model are statistically determined by analysing measurement data. Both the line-of-sight and non-line-of-sight channel conditions are considered in the measurement. Variations of parameter values with the size of human body are analysed along with the variation of parameter values with the surrounding environments. It is observed that the parameters of the path loss model vary with the frequency band as well as with the body size and surrounding environment. The derived parameter values are specific to the particular frequency bands of IEEE 802.15.6 standard, which will be useful for the development of efficient UWB WBAN system.

Optical Studies on Some Aspects of Polyvinyl Alcohol Composite Zns Nanocrystalline Thin Films

Zinc Sulfide (ZnS) nanoparticles were grown into the polyvinyl alcohol (PVA) matrix and were synthesized at 70°C by chemical route. The particle size and surface morphology were analysed by X‐ray diffraction (XRD), High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Electron Microscopy (SEM). Optical absorption spectrum showed strong blue shift, which is an indication of strong quantum confinement. Photoluminescence spectrum shows the blue luminescence peaks, which can be attributed to the recombination of the defect states.

All-fiber optic confocal microscope with submicron depth resolution

In the present work an all-fiber optic confocal microscope with submicron depth resolution is reported. The operation of the microscope is based on the principle of back reflectance of propagated light from the target in a curve-shaped step-index multimode optical fiber. Modulation of the back-reflected light with axial displacement of the target is monitored using a photodiode (PD). The advantage of the system is its simplicity and possibility of remote monitoring. An axial displacement of minimum 0.5 μm can be detected within the focusing depth with the present work.