Showing papers by "Jianqing Wang published in 2009"
TL;DR: Using the frequency-dependent finite-difference time domain method and a realistic human body model, an on-body propagation model is derived and the model parameters for some representative transmission links on the human body are determined.
Abstract: On-body area ultrawideband (UWB) communication is of high importance for promising new biomedical applications. However, there are currently few measurements or models describing on-body area propagation channels which put an emphasis on various body postures. Using the frequency-dependent finite-difference time domain (FDTD) method and a realistic human body model, we simulate various body postures for modeling on-body channels. Based on the FDTD numerical results, we derive an on-body propagation model and determine the model parameters for some representative transmission links on the human body. A good match is obtained between the data derived from FDTD and the statistically implemented models in terms of key communication metrics. In addition, for the chest-to-right-waist transmission link, an experiment is performed in order to verify the results from the FDTD method, and it is found that the model parameters agree well between the two approaches.
137 citations
TL;DR: In this paper, a homogeneous cylinder is used as an arm model, and the characteristic of electromagnetic field distribution around the cylinder is extracted based on surface wave approximation and numerical analysis, respectively.
Abstract: In this study, an electromagnetic field approach is used to clarify the mechanism of on-body transmission. A homogeneous cylinder is used as an arm model, and the characteristic of electromagnetic field distribution around the cylinder is extracted based on surface wave approximation and numerical analysis, respectively. As a result, the surface wave approximation is found to be valid in the far-field region from the excitation source in the frequency range of 10-150 MHz. Moreover, in the near-field region of the excitation source, the attenuation along the cylinder surface is much smaller than that toward the outside. In addition, by using a numerical human body model, the path loss for on-body transmission is also formulated.
61 citations
16 Oct 2009
TL;DR: In this paper, the performance of wearable and implant BAN links on chest, which correspond to communication links of chest-to-waist and chest inside-tooutside respectively, are investigated.
Abstract: Ultra wideband (UWB) communication is a promising technique for biomedical body area networks (BAN). In this paper, the performance of wearable and implant BAN links on chest, which correspond to communication links of chest-to-waist and chest inside-to-outside respectively, are investigated. The channel models are first derived based on the frequency-dependent finite difference time domain (FDTD) method and a realistic-shaped human body model with an emphasis on the statistical variations of body postures. Then the bit error rates (BER) for a RAKE receiver are obtained for these two links.
47 citations
TL;DR: In this article, the performance of an on-body UWB chest-to-waist link, which corresponds to a communication link from a biotical sensor at the chest to a coordinator receiver at the waist, is investigated.
Abstract: On-body area ultra wideband (UWB) communication is promising for biomedical applications. In this letter, the performance of an on-body UWB chest-to-waist link, which corresponds to a communication link from a biotical sensor at the chest to a coordinator receiver at the waist, is investigated. The channel model is first derived based on the frequency-dependent finite difference time domain method and a realistic-shaped human body model with an emphasis on the statistical variations of body postures. Then the bit error rate for a RAKE receiver is obtained.
38 citations
01 Nov 2009
TL;DR: The bit error rate performance has shown the validity of the system in the in-body to out-of-body chest channel, and the generated model shows good agreement with the FDTD-calculated result in terms of key communication metrics.
Abstract: The objective of this study is to investigate the feasibility of an ultra wideband (UWB) impulse radio system for in-body to out-of-body wireless communication for biomedical applications. At first, a UWB antenna is designed in the UWB low band for implant use in the chest. Then the channel model is extracted and established based on finite difference time domain (FDTD) simulation with an anatomical human body model. The established channel model consists of a small set of parameters for generating discrete time impulse responses. The generated model shows good agreement with the FDTD-calculated result in terms of key communication metrics. For effective communication over the multipath-affected channel, the pulse position modulation is employed and a 2-finger RAKE structure with a constant temporal delay is proposed in the receiver. The bit error rate performance has shown the validity of the system in the in-body to out-of-body chest channel.
38 citations
TL;DR: No adverse effects of EMF exposure were observed on any reproductive and embryotoxic parameters such as number of live, dead or resorbed embryos, placental weights, sex ratios, weights or external, visceral or skeletal abnormalities of live fetuses.
Abstract: The present study was designed to evaluate whether gestational exposure to an EMF targeting the head region, similar to that from cellular phones, might affect embryogenesis in rats. A 1.95-GHz wide-band code division multiple access (W-CDMA) signal, which is one applied for the International Mobile Telecommunication 2000 (IMT-2000) system and used for the freedom of mobile multimedia access (FOMA), was employed for exposure to the heads of four groups of pregnant CD(SD) IGS rats (20 per group) for gestational days 7-17. The exposure was performed for 90 min/day in the morning. The spatial average specific absorption rate (SAR) for individual brains was designed to be 0.67 and 2.0 W/kg with peak brain SARs of 3.1 and 7.0 W/kg for low (group 3) and high (group 4) exposures, respectively, and a whole-body average SAR less than 0.4 W/kg so as not to cause thermal effects due to temperature elevation. Control and sham exposure groups were also included. At gestational day 20, all dams were killed and fetuses were taken out by cesarean section. There were no differences in maternal body weight gain. No adverse effects of EMF exposure were observed on any reproductive and embryotoxic parameters such as number of live (243-271 fetuses), dead or resorbed embryos, placental weights, sex ratios, weights or external, visceral or skeletal abnormalities of live fetuses.
36 citations
TL;DR: Dark neurons, assessed using hematoxylin and eosin staining, were rarely present, with no statistically significant difference between exposed and sham-exposed animals, and this study thus failed to confirm the results of Salford et al.
Abstract: Masuda, H., Ushiyama, A., Takahashi, M., Wang, J., Fujiwara, O., Hikage, T., Nojima, T., Fujita, K., Kudo, M. and Ohkubo, C. Effects of 915 MHz Electromagnetic-Field Radiation in TEM Cell on the Blood-Brain Barrier and Neurons in the Rat Brain. Radiat. Res. 172, 66-73 (2009). The aim of this study was to determine whether albumin leakage and dark neurons were present in rat brains 14 and 50 days after a single 2-h exposure to a 915 MHz electromagnetic field, as reported by Salford et al. (Environ. Health Perspect. 111, 881–883, 203). Sixty-four male F344 rats (12 weeks old) were exposed to a 915 MHz electromagnetic field at whole-body average specific absorption rates of 0, 0.02, 0.2 and 2.0 W/kg in TEM cells for 2 h, following the protocol reported by Salford et al. The brains were examined histologically and immunohistochemically. No albumin immunoreactivity was observed in the exposed groups. In addition, dark neurons, assessed using hematoxylin and eosin staining, were rarely present, with no...
35 citations
TL;DR: Two approaches are proposed for the specific energy absorption (SA) and the specific absorption rate (SAR) calculation and it is shown that the two approaches have the same accuracy but the time-domain approach is more straightforward in the numerical analysis.
Abstract: With the rapid progress of electronic and information technology, an expectation for the realization of body area network (BAN) by means of ultra wide band (UWB) techniques has risen. Although the signal from a single UWB device is very low, the energy absorption may increase significantly when many UWB devices are simultaneously adorned to a human body. An analysis method is therefore required from the point of view of biological safety evaluation. In this study, two approaches, one is in the time domain and the other is in the frequency domain, are proposed for the specific energy absorption (SA) and the specific absorption rate (SAR) calculation. It is shown that the two approaches have the same accuracy but the time-domain approach is more straightforward in the numerical analysis. By using the time-domain approach, SA and SAR calculation results are given for multiple UWB pulse exposure to an anatomical human body model under the Federal Communications Commission (FCC) UWB limit.
14 citations
TL;DR: In this article, the FDTD method was used to investigate how ground-layer slits affect the above conduction noise currents, and the results showed that the crosstalk levels do not always increase with the slit number, which can be reduced by the slit layout.
Abstract: Electromagnetic disturbances for vehicle-mounted radios are well known to be caused mainly by conduction noise currents flowing out wire harnesses from printed circuit boards (PCBs) having a common ground layer with slits. In this study, in order to investigate how ground-layer slits affect the above conduction noise currents, we paid FM band induced voltages or crosstalks on the trace connected to the wire harnesss, and simulated with the FDTD method the crosstalk levels between two traces perpendicularly fabricated on three kinds of simple PCBs with different ground-layer slits, which were compared with measurement in the frequency range from 10 MHz to 1 GHz. As a result, we could confirm that the FDTD calculation approximately agrees with the measured results, and also that the crosstalk levels do not always increase with the slit number, which can be reduced by the slit layout.
8 citations
13 Feb 2009
TL;DR: In this article, the environmental static magnetic field and electromagnetic fields of various frequencies were measured around the Large Helical Device (LHD), a fusion plasma facility located in Japan, and the measured leaks were less than occupational regulation levels.
Abstract: The environmental static magnetic field and electromagnetic fields of various frequencies were measured around the Large Helical Device (LHD), a fusion plasma facility located in Japan. The LHD uses a superconducting magnet coil system and high-power plasma heating devices. Usually, leakage of the static magnetic field strength was less than 0.1 mT, but it varied according to the experimental conditions and protection of the operating coils. Leakage of the electric and magnetic fields from the Ion Cyclotron Range of Frequency (ICRF) plasma heating sources of 25-100 MHz were observed in bursts of either a short time or a long time according to particular plasma experiments, but the measured leaks were less than occupational regulation levels. Also, extremely low frequency (ELF) electromagnetic levels were measured near the magnetic coil power supply boxes, and high magnetic strength was observed. As a whole, the electromagnetic fields of the magnetic fusion experimental facility have various frequencies and time-dependent variable fields. Therefore, this facility should be precisely monitored to make proposal for a suitable safety management system.
4 citations