WBAN Channel Modeling for 900 MHz and 60 GHz Communications

This article deals with the experimental characterization of the on-body propagation channel for applications in wireless body area networks (WBANs). The on-body propagation was studied between two quarter-wavelength monopole antennas in the 900 MHz band and between two horn antennas in the 55-65 GHz range. Different locations all over the body, including arm, leg, and front and back of the torso, were studied for two human male subjects. The channel parameters in terms of path gain and delay spread were extracted from measurements for vertical and horizontal polarizations of the antennas in both frequency bands. In addition, a wrist to arm path was studied in the 60 GHz band where the transmitter was rotated in 360 degrees around the arm at a fixed distance from the receiver. We obtained a path gain exponent between 2 and 3 in the 900 MHz band and in the 2.4-6 range for the 60 GHz band. Higher path gains for vertical and horizontal polarizations were obtained in the 900 MHz and 60 GHz bands, respectively. Maximum mean excess delay and root-mean-square delay spread were 6.3 ns and <2 ns in the 900 MHz band, respectively, while these values decreased by factors 3 and 10 in the 60 GHz band.