Analysis of on-body communication channels with consideration of wave absorbers emulating free space

Abstract

In wireless body area networks (WBANs) measurements, the performance of on-body channels has been affected by surrounding environment. When conducting WBAN measurement in full anechoic chamber, the on-body signal propagation might be influenced by wave absorbers especially the on-floor wave absorbers (as they are close to human body). In this paper, the simulation approach, based on the frequency-dependent finite-difference time-domain (FD2TD) method, is employed to examine their effects to the characteristics of the electromagnetic (EM) wave propagation around human body model. Two types, the multi-layer planar and pyramid, of wave absorbers are investigated. The received signal at the focused frequency of 2.45 GHz for different combinations of source excitation directions with various on-body links are extracted using Fourier transform. The received signal deviations due to a small change of receiver position are also discussed. With limited conditions in this study, the simulation results show that there are no significant difference of the received E-field strength (mostly below 1 dB) between both types of wave absorbers. Comparing to the conventional model (without wave absorbers), both types of the on-floor wave absorbers have affected to the received E-field strength at the ankle and thigh locations with the discrepancy up to 10 dB.