Khaleda Ali

A whole body statistical shape model for radio frequency simulation

The development of ultra low power wireless sensors for customized wearable and implantable medical devices requires patient specific models for radio frequency simulation to understand wave propagation in the body. In practice, the creation of a patient specific whole-body model is difficult and time consuming to create. It is therefore necessary to establish a method for studying a population in a statistical manner. In this paper, we present a statistical shape model for the whole body for RF simulation. It is built from 10 male and 10 female subjects of varying size and height. This model has the ability to instantiate a new surface mesh with the parameters allowed by the training set. This model would provide shapes of varying sizes for studies, without the requirement of obtaining subject specific whole body models. Results from finite-differences time-domain simulation are presented on the extreme shapes from the model and demonstrate the need for a full understanding of the range in body shapes.

Quantitative Analysis of the Subject-Specific On-Body Propagation Channel Based on Statistically Created Models

This letter presents a quantitative approach to the investigation of subject-specific on-body communication channels. To this aim, propagation at 5.8 GHz has been studied considering 50 realistic digital phantoms, statistically generated from a set of 20 magnetic resonance (MR) scans. Both line-of-sight (LoS) and non-line-of-sight (NLoS) communication links have been taken into account. Mathematical expressions are proposed reflecting the correlation between body dimensions (specifically height and waist) and path-loss variation. Results show that linear fitting can be extrapolated between path-loss variations and body shape parameters. In-house parallel finite-difference time-domain (PFDTD) numerical method has been applied to carry out full-wave simulations on the 50 digital phantoms.

Numerical analysis of on-body channel for statistically-generated body shapes

The development of ultra low power wireless sensors for customized wearable medical devices requires patient specific information for the evaluation of the on-body communication channel. Direct measurements on human subjects are impractical for many applications. In such cases, numerical techniques for electromagnetic analysis, such as Finite Differences in Time Domain (FDTD), is an attractive alternative. To this end, it is necessary to create whole-body models that are representative to the population data. In this paper, RF simulation is performed on shapes generated from a range of subjects. A whole body statistical shape model is generated from twenty subjects of varying sizes and height. The simulations show the dependence of path loss on subject specific cases. The human models of higher size and higher curvature have greater path loss which is analogous to real cases, suggesting the practical value of the model. Five different extreme human body shapes obtained from the statistical models, and the results from FDTD simulations at 2.4 GHz are presented.

Investigation of the effect of fabric in on-body communication using Finite Difference Time Domain technique at 60GHz

An investigation of the effects of fabric over skin, evaluated in terms of transmission coefficient of a five layer model comprising of air-cloth-air-skin-air, is presented in this paper. The analysis is performed in the range of the millimeter waves at 60 GHz. The full wave numerical method Finite Differences Time Domain (FDTD) is used to analyze the investigated fabric-air-skin model. In order to avoid scattering from the edge, a two dimensional model has been considered and Periodic Boundary Conditions (PBC) have been imposed. The effect of varying depth of fabric causes change of transmission coefficient of skin from 10-18%. Results show the value of the transmission coefficient being strictly dependent on the thickness of both the fabric and the air gap between clothes and skin.

An investigation on the surface wave characteristics at 2.4 and 60 GHz for on-body communications

Over the past few years, body-centric wireless communication systems have attracted significant interest from both the academic and industrial community. The availability of low-cost miniaturized electronic components has led to the rapid growth of WBAN in various applications. In healthcare, BANs can provide cost-effective solutions for monitoring chronically ill patients, or non-invasive alternatives to traditional diagnosing techniques such as blood-glucose monitoring for diabetic subjects. The commercial electronics market has also been very responsive to demands from the field of sports and fitness. To sustain this enormous growth of wearable industry, it is necessary to develop reliable and efficient systems working at various frequency spectrums. Accurate knowledge of the communication channel in the vicinity of the human body will be an essential prerequisite in this regard. A wide amount of groundwork has already been carried out in terms of measurement and simulation for analyzing the channel characteristics up to 10 GHz. It is observed that creeping waves significantly influence the on-body communication channels, especially in the shadowed regions. However, characterization of such wave components at V band is by no means a trivial task. The objective of this work is to perform comparative investigation on the on-body channel characteristics at narrow band and V Band regions of microwave spectrum.

Impact of body shape on BAN communication channel at 5.8 GHz

The continuous interest of both the academic community and the industrial world in wearable devices is driving an ever more extensive research activity on Body Area Networks (BANs). According to the definition provided by the IEEE 802.15 Working Group, they can be defined as a communication system “optimized for low power devices and operation on, in or around the human body (but not limited to humans) to serve a variety of applications including medical, consumer electronics, personal entertainment and other”. In order to ensure that the system is truly optimized, it is of paramount importance to understand how different body shapes affect the characteristics of the propagation channel.

Shadowing effect of upper limbs in body-centric communication at W band

Body-centric wireless communications continue to raise the interest of the research community, and the major electronics companies now have a line of wearable devices. Applications are becoming more and more complex, requiring high data rate and robust, reliable communication links. The portion of the frequency spectrum currently being considered for Body Area Networks (BAN), which goes up to 10 GHz, is however already significantly overcrowded, as it includes widespread applications such as mobile phone communications and wireless LAN. Therefore the use of millimeter wave frequencies is being investigated: particularly the bands around 60 GHz and 90 GHz seem promising, since they have been released for unlicensed use by the Federal Communications Commission (FCC), and may easily provide data rates higher than 1 Gb/s (J. Wells, IEEE Microw. Mag., Vol. 10, Issue 3, pp. 104-112, 2009).

Numerical investigation on the dependence of on-body channel characteristics on anthropomorphic variation of human body

A numerical investigation focusing on the correlation between on-body channel characteristics and the morphological variation of body is presented in the paper. The analysis has been carried out at 5.8GHz and a parallel version of Finite Difference Time Domain (FDTD) has been employed. Fifty digital phantoms are adopted in the simulation domain. Parameters explored for the concerned study are path loss and channel capacity. Results demonstrate that for models with similar dimensions around waist, a change of 50cms in height can cause a variation of 20% in path loss exponent and 35% in channel capacity per unit hertz.